Code Help.....
09-07-2007 | 02:17 AM
#1
Thread Starter
TECH Fanatic
Joined: Jan 2005
Posts: 1,489
Likes: 0
From: Lafayette, Louisiana
Code Help.....
Ok I keep getting these codes and its going into Limp Mode
B1000 - ECU Malfunction (History) (Immature)
U1088 - Loss of communication with SDM (History) (Immature)
C0265 or C0266 - EBCM Relay Circut (History)
C0281 - Brake Switch Circut (History)
Can anybody help me with this?
B1000 - ECU Malfunction (History) (Immature)
U1088 - Loss of communication with SDM (History) (Immature)
C0265 or C0266 - EBCM Relay Circut (History)
C0281 - Brake Switch Circut (History)
Can anybody help me with this?
09-07-2007 | 06:49 PM
#4
TECH Senior Member
Joined: Jul 2006
Posts: 7,023
Likes: 0
From: Somewhere around -199C
DTC B1000
Circuit Description
The internal fault detection is handled inside the control module. No external circuits are involved.
Conditions for Running the DTC
The module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.
Conditions for Setting the DTC
The module has detected an internal malfunction.
Action Taken When the DTC Sets
The module refuses all additional inputs.
Conditions for Clearing the DTC
A current DTC clears when the malfunction is no longer present.
A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
Diagnostic Aids
This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
If this DTC is retrieved as both a current and history DTC, replace the module.
Step
Action
Yes
No
1
Did you perform the Diagnostic System Check for the system exhibiting the symptom?
Go to Step 2
Go to Control Module References for the applicable Diagnostic System Check
2
Install a scan tool.
Turn ON the ignition, with the engine OFF.
Retrieve DTCs.
Is the DTC retrieved as a current DTC?
Go to Step 3
Go to Diagnostic Aids
3
Important
Perform the programming or setup procedure for the module if required.
Replace the control module setting the DTC as current. Refer to Control Module References .
Did you complete the replacement?
Go to Step 4
--
4
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
Go to Step 2
System OK
Circuit Description
The internal fault detection is handled inside the control module. No external circuits are involved.
Conditions for Running the DTC
The module runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.
Conditions for Setting the DTC
The module has detected an internal malfunction.
Action Taken When the DTC Sets
The module refuses all additional inputs.
Conditions for Clearing the DTC
A current DTC clears when the malfunction is no longer present.
A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
Diagnostic Aids
This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
If this DTC is retrieved as both a current and history DTC, replace the module.
Step
Action
Yes
No
1
Did you perform the Diagnostic System Check for the system exhibiting the symptom?
Go to Step 2
Go to Control Module References for the applicable Diagnostic System Check
2
Install a scan tool.
Turn ON the ignition, with the engine OFF.
Retrieve DTCs.
Is the DTC retrieved as a current DTC?
Go to Step 3
Go to Diagnostic Aids
3
Important
Perform the programming or setup procedure for the module if required.
Replace the control module setting the DTC as current. Refer to Control Module References .
Did you complete the replacement?
Go to Step 4
--
4
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
Go to Step 2
System OK
09-07-2007 | 06:50 PM
#5
TECH Senior Member
Joined: Jul 2006
Posts: 7,023
Likes: 0
From: Somewhere around -199C
DTC U1001-U1254
Circuit Description
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for State of Health monitoring. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that modules Node Alive message. Each module ON the class 2 serial data circuit which is powered and performing functions that require detection of a communications malfunction is required to send a Node Alive message every 2 seconds. When no message is detected from a learned identification number for 5 seconds, a DTC U1xxx is set.
The Control Module ID Number list provides a method for determining which module is not communicating. A module with an internal class 2 serial data circuit malfunction or which loses power during the current ignition cycle would have a Lost Communication DTC set by other modules. Use the Control Module ID Number list in order to determine which module is not communicating and the Lost Communications with XXX diagnostic table in order to diagnose the malfunction. When no message is detected from a learned identification number for 5 seconds, a DTC U1xxx is set.
Control Module
ID Number
PCM
016
TCM
024
TCSCM
026
EBCM
041
SCM
056
BCM
064
SDM
088
IPC
096
DIC
097
ONS
151
HCM
152
MSM
166
MMM
169
When more than one Loss of Communication DTC is set in a single module or among multiple modules, diagnose the DTCs in the following order:
Current DTCs before history DTCs except as specified in the diagnostic tables.
The DTC which is reported the most times.
From the lowest number DTC to the highest number DTC.
Conditions for Running the DTC
Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.
DTCs U1300, U1301 or U1305 do not have a current status.
The vehicle power mode requires serial data communication to occur.
Conditions for Setting the DTC
A message from a learned identification number has not been detected for the past 5 seconds.
Conditions for Clearing the DTC
A current DTC clears when the malfunction is no longer present.
A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
A module which loses power during an ignition cycle will cause other module to set lost communication DTCs.
A module which loses power during an ignition cycle will cause other module to set lost communication DTCs.
The malfunction is due to an open in the class 2 serial data circuit or an open in the module.
The module which was not communicating due to an open in the class 2 serial data circuit may have set lost communication DTCs for those modules that it was monitoring.
The modules which can communicate indicate the module which cannot communicate. You must clear the DTCs from these modules to avoid future misdiagnosis.
Step
Action
Yes
No
1
Test the following circuits of the module that is not communicating:
Switched battery input voltage
Ignition input voltage
Ignition output voltage
for an
Open
Short to ground
Refer to:
Control Module References in Body Control System for the applicable schematic
Circuit Testing in Wiring Systems
Wiring Repairs in Wiring Systems
Did you find and correct the condition?
Go to Step 9
Go to Step 2
2
Test the ground circuits of the module that is not communicating for an open.
Refer to:
Control Module References in Body Control System for the applicable schematic
Circuit Testing in Wiring Systems
Wiring Repairs in Wiring Systems
Did you find and correct the condition?
Go to Step 9
Go to Step 3
3
Inspect for poor connections at the star connector. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 7
Go to Step 4
4
Test the class 2 circuit of the module that is not communicating for an open between the module and the star connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 7
Go to Step 5
5
Inspect for poor connections at the following locations, for the module that is not communicating:
Switched battery input voltage circuits
Ignition input voltage circuits
Ignition output voltage circuits
Ground circuits
Class 2 circuits
Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 7
Go to Step 6
6
Important
Replace and reprogram the module which is not communicating. Refer to Control Module References in Body Control System for the appropriate repair instructions.
Did you complete the replacement?
Go to Step 9
--
7
Connect a scan tool.
Turn ON the ignition leaving the engine OFF.
Select the Display DTCs function for the module which was not communicating.
Does the scan tool display any DTCs which do not begin with a "U"?
Go to Control Module References in Body Control System for the applicable Diagnostic System Check
Go to Step 8
8
Use the scan tool to clear the DTCs.
Did you clear all DTCs?
Go to Step 9
--
9
Select the Display DTCs function for the modules which had the Lost Communications with XXX DTC set.
Does the scan tool display any DTCs which do not begin with a "U"?
Go to Control Module References in Body Control System for the applicable Diagnostic System Check
Go to Step 10
10
Use the scan tool to clear the DTCs.
Continue diagnosing or clearing the DTCs until all the modules have been diagnosed and all the DTCs have been cleared.
Did you complete the action?
System OK
--
Circuit Description
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for State of Health monitoring. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that modules Node Alive message. Each module ON the class 2 serial data circuit which is powered and performing functions that require detection of a communications malfunction is required to send a Node Alive message every 2 seconds. When no message is detected from a learned identification number for 5 seconds, a DTC U1xxx is set.
The Control Module ID Number list provides a method for determining which module is not communicating. A module with an internal class 2 serial data circuit malfunction or which loses power during the current ignition cycle would have a Lost Communication DTC set by other modules. Use the Control Module ID Number list in order to determine which module is not communicating and the Lost Communications with XXX diagnostic table in order to diagnose the malfunction. When no message is detected from a learned identification number for 5 seconds, a DTC U1xxx is set.
Control Module
ID Number
PCM
016
TCM
024
TCSCM
026
EBCM
041
SCM
056
BCM
064
SDM
088
IPC
096
DIC
097
ONS
151
HCM
152
MSM
166
MMM
169
When more than one Loss of Communication DTC is set in a single module or among multiple modules, diagnose the DTCs in the following order:
Current DTCs before history DTCs except as specified in the diagnostic tables.
The DTC which is reported the most times.
From the lowest number DTC to the highest number DTC.
Conditions for Running the DTC
Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.
DTCs U1300, U1301 or U1305 do not have a current status.
The vehicle power mode requires serial data communication to occur.
Conditions for Setting the DTC
A message from a learned identification number has not been detected for the past 5 seconds.
Conditions for Clearing the DTC
A current DTC clears when the malfunction is no longer present.
A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
A module which loses power during an ignition cycle will cause other module to set lost communication DTCs.
A module which loses power during an ignition cycle will cause other module to set lost communication DTCs.
The malfunction is due to an open in the class 2 serial data circuit or an open in the module.
The module which was not communicating due to an open in the class 2 serial data circuit may have set lost communication DTCs for those modules that it was monitoring.
The modules which can communicate indicate the module which cannot communicate. You must clear the DTCs from these modules to avoid future misdiagnosis.
Step
Action
Yes
No
1
Test the following circuits of the module that is not communicating:
Switched battery input voltage
Ignition input voltage
Ignition output voltage
for an
Open
Short to ground
Refer to:
Control Module References in Body Control System for the applicable schematic
Circuit Testing in Wiring Systems
Wiring Repairs in Wiring Systems
Did you find and correct the condition?
Go to Step 9
Go to Step 2
2
Test the ground circuits of the module that is not communicating for an open.
Refer to:
Control Module References in Body Control System for the applicable schematic
Circuit Testing in Wiring Systems
Wiring Repairs in Wiring Systems
Did you find and correct the condition?
Go to Step 9
Go to Step 3
3
Inspect for poor connections at the star connector. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 7
Go to Step 4
4
Test the class 2 circuit of the module that is not communicating for an open between the module and the star connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 7
Go to Step 5
5
Inspect for poor connections at the following locations, for the module that is not communicating:
Switched battery input voltage circuits
Ignition input voltage circuits
Ignition output voltage circuits
Ground circuits
Class 2 circuits
Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 7
Go to Step 6
6
Important
Replace and reprogram the module which is not communicating. Refer to Control Module References in Body Control System for the appropriate repair instructions.
Did you complete the replacement?
Go to Step 9
--
7
Connect a scan tool.
Turn ON the ignition leaving the engine OFF.
Select the Display DTCs function for the module which was not communicating.
Does the scan tool display any DTCs which do not begin with a "U"?
Go to Control Module References in Body Control System for the applicable Diagnostic System Check
Go to Step 8
8
Use the scan tool to clear the DTCs.
Did you clear all DTCs?
Go to Step 9
--
9
Select the Display DTCs function for the modules which had the Lost Communications with XXX DTC set.
Does the scan tool display any DTCs which do not begin with a "U"?
Go to Control Module References in Body Control System for the applicable Diagnostic System Check
Go to Step 10
10
Use the scan tool to clear the DTCs.
Continue diagnosing or clearing the DTCs until all the modules have been diagnosed and all the DTCs have been cleared.
Did you complete the action?
System OK
--
09-07-2007 | 06:51 PM
#6
TECH Senior Member
Joined: Jul 2006
Posts: 7,023
Likes: 0
From: Somewhere around -199C
Subject: ABS Light On, DTCs C0265, C0201, U1041 Set and/or Loss of Communication with Brake Module (Reground EBCM Ground) #04-05-25-002D - (06/14/2007)
Models: 2004-2007 Buick Rainier
2002-2006 Cadillac Escalade, Escalade EXT
2003-2006 Cadillac Escalade ESV
1999-2007 Chevrolet Silverado Classic
2000-2006 Chevrolet Suburban, Tahoe
2002-2006 Chevrolet Avalanche
2002-2007 Chevrolet TrailBlazer, TrailBlazer EXT
2003-2006 Chevolet SSR
1999-2007 GMC Sierra Classic
2000-2006 GMC Yukon, Yukon Denali, Yukon XL
2002-2007 GMC Envoy, Envoy XL, Sierra Denali Classic
2004-2005 GMC Envoy XUV
2002-2004 Oldsmobile Bravada
--------------------------------------------------------------------------------
This bulletin is being revised to update model years. Please discard Corporate Bulletin Number 04-05-25-002C (Section 05 -- Brakes).
--------------------------------------------------------------------------------
Condition
Some customers may comment that the ABS light is on. Upon further inspection, DTCs C0265 and C0201 may be set in the brake module. It is also possible for DTC U1041 to set in other modules. There may also be a loss of communication with the brake module.
Cause
A poor connection at the EBCM ground is causing unnecessary replacements of brake modules.
Important: The EBCM Ground is different for each application. Refer to the list below for the proper ground reference:
• Midsize Utilities = Ground 304
• SSR = Ground 400
• Fullsize Trucks and Utilities = Ground 110
Correction
DO NOT REPLACE THE BRAKE MODULE.
Perform the following steps to improve the connection of the EBCM Ground:
Remove the EBCM Ground. The EBCM Ground is located on the frame beneath the driver's side door. If multiple grounds are found in this location, the EBCM ground can be identified as the heavy (12-gauge) wire.
Clean the area, front and back, using a Whiz Wheel®.
Install the ground, then the washer and then the bolt to the frame.
Important: It is important to use the bolts, washers and nuts specified in this bulletin. These parts have been identified due to their conductive finish.
Install a washer and nut to the back side of the frame.
Tighten
Tighten the nut to 9 N·m (79 lb in).
Cover the front and back side of the repair area using Rubberized Undercoating.
An additional check can be made to ensure a good connection for the Battery Cable to Frame ground. It is possible for this ground to cause similar symptoms with the ABS as described above.
Parts Information
FULL-SIZE TRUCKS, SUVs AND H2
Part Number
Description
11588564
Bolt
15650962
Washer
15672934
Nut
12378398
(in Canada, 10952414)
Rubberized Undercoating -- Paintable
MIDSIZE SUVs
Part Number
Description
11517555
Bolt
15650961
Washer
11503749
Nut
12378398
(in Canada, 10952414)
Rubberized Undercoating -- Paintable
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
N9502
Ground Repair - EBCM Ground
0.2 hr
Models: 2004-2007 Buick Rainier
2002-2006 Cadillac Escalade, Escalade EXT
2003-2006 Cadillac Escalade ESV
1999-2007 Chevrolet Silverado Classic
2000-2006 Chevrolet Suburban, Tahoe
2002-2006 Chevrolet Avalanche
2002-2007 Chevrolet TrailBlazer, TrailBlazer EXT
2003-2006 Chevolet SSR
1999-2007 GMC Sierra Classic
2000-2006 GMC Yukon, Yukon Denali, Yukon XL
2002-2007 GMC Envoy, Envoy XL, Sierra Denali Classic
2004-2005 GMC Envoy XUV
2002-2004 Oldsmobile Bravada
--------------------------------------------------------------------------------
This bulletin is being revised to update model years. Please discard Corporate Bulletin Number 04-05-25-002C (Section 05 -- Brakes).
--------------------------------------------------------------------------------
Condition
Some customers may comment that the ABS light is on. Upon further inspection, DTCs C0265 and C0201 may be set in the brake module. It is also possible for DTC U1041 to set in other modules. There may also be a loss of communication with the brake module.
Cause
A poor connection at the EBCM ground is causing unnecessary replacements of brake modules.
Important: The EBCM Ground is different for each application. Refer to the list below for the proper ground reference:
• Midsize Utilities = Ground 304
• SSR = Ground 400
• Fullsize Trucks and Utilities = Ground 110
Correction
DO NOT REPLACE THE BRAKE MODULE.
Perform the following steps to improve the connection of the EBCM Ground:
Remove the EBCM Ground. The EBCM Ground is located on the frame beneath the driver's side door. If multiple grounds are found in this location, the EBCM ground can be identified as the heavy (12-gauge) wire.
Clean the area, front and back, using a Whiz Wheel®.
Install the ground, then the washer and then the bolt to the frame.
Important: It is important to use the bolts, washers and nuts specified in this bulletin. These parts have been identified due to their conductive finish.
Install a washer and nut to the back side of the frame.
Tighten
Tighten the nut to 9 N·m (79 lb in).
Cover the front and back side of the repair area using Rubberized Undercoating.
An additional check can be made to ensure a good connection for the Battery Cable to Frame ground. It is possible for this ground to cause similar symptoms with the ABS as described above.
Parts Information
FULL-SIZE TRUCKS, SUVs AND H2
Part Number
Description
11588564
Bolt
15650962
Washer
15672934
Nut
12378398
(in Canada, 10952414)
Rubberized Undercoating -- Paintable
MIDSIZE SUVs
Part Number
Description
11517555
Bolt
15650961
Washer
11503749
Nut
12378398
(in Canada, 10952414)
Rubberized Undercoating -- Paintable
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
N9502
Ground Repair - EBCM Ground
0.2 hr
09-07-2007 | 06:52 PM
#7
TECH Senior Member
Joined: Jul 2006
Posts: 7,023
Likes: 0
From: Somewhere around -199C
DTC C0265 or C0266 and C065 or C066
Circuit Description
The ABS relay supplies battery voltage to 6 valve solenoids. The electronic brake control module (EBCM) microprocessor applies the grounds needed to activate each solenoid. The low side of each solenoid coil has a feedback circuit to the EBCM microprocessor. When a solenoid is commanded OFF, the feedback voltage is high. When a solenoid is commanded ON, the feedback voltage is low.
Conditions for Running the DTC
The ignition is ON.
The vehicle speed is greater than 6 km/h (4 mph).
Conditions for Setting the DTC
The EBCM detects an internal malfunction.
Action Taken When the DTC Sets
C0265
If equipped, the following actions occur:
The EBCM disables the DRP/ABS.
The ABS indicator turns ON.
The brake warning indicator turns ON.
C0266
If equipped, the following actions occur:
The EBCM disables the ABS.
The ABS indicator turns ON.
Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
Diagnostic Aids
Important: Whenever the EBCM is replaced for DTC C0265 or C0266, the ABS pump motor and motor circuitry must be tested for the proper resistance. Refer to steps 7 and 8 in the diagnostic table below for testing procedures and resistance values.
C0265
Thoroughly inspect connections and circuitry that may cause an intermittent malfunction. Refer to the following:
• Testing for Intermittent Conditions and Poor Connections
• Testing for Electrical Intermittents
• Connector Repairs
• Wiring Repairs
C0266
Replace the EBCM if DTC C0266 continues to set intermittently.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step tests if the battery positive voltage circuit can supply adequate power to the system relay.
A shorted ABS pump motor or shorted motor circuitry may damage the contacts within the system relay. Follow this step to prevent damage to a replacement EBCM.
Step
Action
Values
Yes
No
Schematic Reference: ABS Schematics
Connector End View Reference: ABS Connector End Views
1
Did you perform the ABS Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check - ABS
2
Use a scan tool in order to clear the DTCs.
Use the scan tool in order to perform an ABS Function Test.
Does DTC C0266 set?
--
Go to Step 7
Go to Step 3
3
Does DTC C0265 set?
--
Go to Step 4
Go to Diagnostic Aids
4
Turn OFF the ignition.
Disconnect from the EBCM, the harness connector containing the battery positive voltage circuit.
Connect a test lamp between the battery positive voltage circuit and a good ground.
Does the test lamp illuminate?
--
Go to Step 6
Go to Step 5
5
Repair the open in the battery positive voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 11
--
6
Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 11
Go to Step 7
7
Important
It may be necessary to separate the EBCM from the BPMV to gain access to the pump motor pigtail connector. If so, refer to Electronic Brake Control Module (EBCM) Replacement .
Disconnect from the EBCM, the ABS pump motor pigtail connector.
Use a DMM in order to measure the resistance across the ABS pump motor.
Does the resistance measure within the specified range?
0.3-1.0 ohms
Go to Step 8
Go to Step 10
8
Use a DMM in order to measure the resistance between the high side of the pump motor and a good ground.
Does the resistance measure less than the specified value?
0L
Go to Step 10
Go to Step 9
9
Important
Use the scan tool in order to perform the Tire Size Calibration procedure and the Trim Level Calibration procedure, if applicable.
Replace the EBCM. Refer to Electronic Brake Control Module (EBCM) Replacement .
Did you complete the replacement?
--
Go to Step 11
--
10
Important
Use the scan tool in order to perform the Tire Size Calibration procedure and the Trim Level Calibration procedure, if applicable.
Replace the EBCM and the BPMV. Refer to Electronic Brake Control Module (EBCM) Replacement and Brake Pressure Modulator Valve (BPMV) Replacement .
Did you complete the replacements?
--
Go to Step 11
--
11
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
--
Go to Step 2
System OK
Circuit Description
The ABS relay supplies battery voltage to 6 valve solenoids. The electronic brake control module (EBCM) microprocessor applies the grounds needed to activate each solenoid. The low side of each solenoid coil has a feedback circuit to the EBCM microprocessor. When a solenoid is commanded OFF, the feedback voltage is high. When a solenoid is commanded ON, the feedback voltage is low.
Conditions for Running the DTC
The ignition is ON.
The vehicle speed is greater than 6 km/h (4 mph).
Conditions for Setting the DTC
The EBCM detects an internal malfunction.
Action Taken When the DTC Sets
C0265
If equipped, the following actions occur:
The EBCM disables the DRP/ABS.
The ABS indicator turns ON.
The brake warning indicator turns ON.
C0266
If equipped, the following actions occur:
The EBCM disables the ABS.
The ABS indicator turns ON.
Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
Diagnostic Aids
Important: Whenever the EBCM is replaced for DTC C0265 or C0266, the ABS pump motor and motor circuitry must be tested for the proper resistance. Refer to steps 7 and 8 in the diagnostic table below for testing procedures and resistance values.
C0265
Thoroughly inspect connections and circuitry that may cause an intermittent malfunction. Refer to the following:
• Testing for Intermittent Conditions and Poor Connections
• Testing for Electrical Intermittents
• Connector Repairs
• Wiring Repairs
C0266
Replace the EBCM if DTC C0266 continues to set intermittently.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step tests if the battery positive voltage circuit can supply adequate power to the system relay.
A shorted ABS pump motor or shorted motor circuitry may damage the contacts within the system relay. Follow this step to prevent damage to a replacement EBCM.
Step
Action
Values
Yes
No
Schematic Reference: ABS Schematics
Connector End View Reference: ABS Connector End Views
1
Did you perform the ABS Diagnostic System Check?
--
Go to Step 2
Go to Diagnostic System Check - ABS
2
Use a scan tool in order to clear the DTCs.
Use the scan tool in order to perform an ABS Function Test.
Does DTC C0266 set?
--
Go to Step 7
Go to Step 3
3
Does DTC C0265 set?
--
Go to Step 4
Go to Diagnostic Aids
4
Turn OFF the ignition.
Disconnect from the EBCM, the harness connector containing the battery positive voltage circuit.
Connect a test lamp between the battery positive voltage circuit and a good ground.
Does the test lamp illuminate?
--
Go to Step 6
Go to Step 5
5
Repair the open in the battery positive voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 11
--
6
Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 11
Go to Step 7
7
Important
It may be necessary to separate the EBCM from the BPMV to gain access to the pump motor pigtail connector. If so, refer to Electronic Brake Control Module (EBCM) Replacement .
Disconnect from the EBCM, the ABS pump motor pigtail connector.
Use a DMM in order to measure the resistance across the ABS pump motor.
Does the resistance measure within the specified range?
0.3-1.0 ohms
Go to Step 8
Go to Step 10
8
Use a DMM in order to measure the resistance between the high side of the pump motor and a good ground.
Does the resistance measure less than the specified value?
0L
Go to Step 10
Go to Step 9
9
Important
Use the scan tool in order to perform the Tire Size Calibration procedure and the Trim Level Calibration procedure, if applicable.
Replace the EBCM. Refer to Electronic Brake Control Module (EBCM) Replacement .
Did you complete the replacement?
--
Go to Step 11
--
10
Important
Use the scan tool in order to perform the Tire Size Calibration procedure and the Trim Level Calibration procedure, if applicable.
Replace the EBCM and the BPMV. Refer to Electronic Brake Control Module (EBCM) Replacement and Brake Pressure Modulator Valve (BPMV) Replacement .
Did you complete the replacements?
--
Go to Step 11
--
11
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
--
Go to Step 2
System OK
Trending Topics
09-07-2007 | 06:53 PM
#8
TECH Senior Member
Joined: Jul 2006
Posts: 7,023
Likes: 0
From: Somewhere around -199C
DTC C0281 or C081
Circuit Description
The stop lamp switch signal informs the electronic brake control module (EBCM) when the brake pedal is pressed.
Conditions for Running the DTC
Either of the following conditions will cause the DTC to run:
The ignition is ON and the vehicle achieves at least 56 km/h (35 mph) before coming to a stop.
The ignition is ON and the vehicle experiences an antilock brake system (ABS) event lasting at least 1 second.
Conditions for Setting the DTC
The EBCM detects an open or shorted brake switch or brake switch circuit.
Action Taken When the DTC Sets
This information-only DTC is stored in EBCM memory until it is cleared by using the specified procedure.
Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:
• Testing for Electrical Intermittents
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Connector Repairs
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step tests for a shorted stoplamp switch.
This step tests for an open stoplamp switch.
Step
Action
Yes
No
Schematic Reference: ABS Schematics
1
Did you perform the ABS Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - ABS
2
Install a scan tool.
Select the 4WAL 3 Sensor Data Display function.
Observe the Brake Switch Status on the scan tool.
Does the scan tool display Off?
Go to Step 3
Go to Step 5
3
Apply the brake.
Observe the Brake Switch Status on the scan tool.
Does the scan tool display On?
Go to Diagnostic Aids
Go to Step 4
4
Turn OFF the ignition.
Disconnect the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.
Turn ON the ignition.
Observe the Brake Switch Status on the scan tool.
Does the scan tool display On?
Go to Step 9
Go to Step 7
5
Turn OFF the ignition.
Disconnect the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.
Connect a fused jumper wire between the ignition 3 voltage circuit and the TCC brake switch signal circuit at the stop lamp switch harness connector. Refer to Using Fused Jumper Wires in Wiring Systems.
Turn ON the ignition.
Observe the Brake Switch Status on the scan tool.
Does the scan tool display Off?
Go to Step 9
Go to Step 6
6
Test the ignition 3 voltage circuit and the TCC brake switch signal circuit for an open or a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 8
7
Test the TCC brake switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 8
8
Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 10
9
Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 11
10
Important
Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure.
Replace the EBCM. Refer to Electronic Brake Control Module (EBCM) Replacement .
Did you complete the replacement?
Go to Step 12
--
11
Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.
Did you complete the replacement?
Go to Step 12
--
12
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
Go to Step 2
System OK
Circuit Description
The stop lamp switch signal informs the electronic brake control module (EBCM) when the brake pedal is pressed.
Conditions for Running the DTC
Either of the following conditions will cause the DTC to run:
The ignition is ON and the vehicle achieves at least 56 km/h (35 mph) before coming to a stop.
The ignition is ON and the vehicle experiences an antilock brake system (ABS) event lasting at least 1 second.
Conditions for Setting the DTC
The EBCM detects an open or shorted brake switch or brake switch circuit.
Action Taken When the DTC Sets
This information-only DTC is stored in EBCM memory until it is cleared by using the specified procedure.
Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:
• Testing for Electrical Intermittents
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Connector Repairs
Test Description
The numbers below refer to the step numbers on the diagnostic table.
This step tests for a shorted stoplamp switch.
This step tests for an open stoplamp switch.
Step
Action
Yes
No
Schematic Reference: ABS Schematics
1
Did you perform the ABS Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - ABS
2
Install a scan tool.
Select the 4WAL 3 Sensor Data Display function.
Observe the Brake Switch Status on the scan tool.
Does the scan tool display Off?
Go to Step 3
Go to Step 5
3
Apply the brake.
Observe the Brake Switch Status on the scan tool.
Does the scan tool display On?
Go to Diagnostic Aids
Go to Step 4
4
Turn OFF the ignition.
Disconnect the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.
Turn ON the ignition.
Observe the Brake Switch Status on the scan tool.
Does the scan tool display On?
Go to Step 9
Go to Step 7
5
Turn OFF the ignition.
Disconnect the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.
Connect a fused jumper wire between the ignition 3 voltage circuit and the TCC brake switch signal circuit at the stop lamp switch harness connector. Refer to Using Fused Jumper Wires in Wiring Systems.
Turn ON the ignition.
Observe the Brake Switch Status on the scan tool.
Does the scan tool display Off?
Go to Step 9
Go to Step 6
6
Test the ignition 3 voltage circuit and the TCC brake switch signal circuit for an open or a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 8
7
Test the TCC brake switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 8
8
Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 10
9
Inspect for poor connections at the harness connector of the stop lamp switch. Refer to Testing for Intermittent and Poor Connections and to Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 11
10
Important
Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure.
Replace the EBCM. Refer to Electronic Brake Control Module (EBCM) Replacement .
Did you complete the replacement?
Go to Step 12
--
11
Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.
Did you complete the replacement?
Go to Step 12
--
12
Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?
Go to Step 2
System OK
09-09-2007 | 03:00 PM
#9
Thread Starter
TECH Fanatic
Joined: Jan 2005
Posts: 1,489
Likes: 0
From: Lafayette, Louisiana
OK I been in the woods, Just got back today and now its getting worse. Its doing it every day.
The codes have been cleared and they come right back. I have another computer that I am thinking about putting in the truck. Its the stock one that has never been flashed before.
Why does this **** happen when Im about to sell the truck.
I just got a new battery too --- could that cause some trouble?
The codes have been cleared and they come right back. I have another computer that I am thinking about putting in the truck. Its the stock one that has never been flashed before.
Why does this **** happen when Im about to sell the truck.
I just got a new battery too --- could that cause some trouble?
09-09-2007 | 07:49 PM
#10
You can check and make sure your terminals are tight and clean, but it almost seems like your computer is taking a 
with you...
and LSU sux!!!!! thats why your pcms going out, you pull for a rotten team!!!
with you...and LSU sux!!!!! thats why your pcms going out, you pull for a rotten team!!!