My truck keeps giving me a P0748 code. I will erase it with my predator but if get into the boost hard than it just comes back. I just put a new tranny in so I guess it wouldn't be in the tranny. I was having the same problem before the tranny but I thought the new one would fix it. guess not please help.

 

My truck was doing the same thing. Rick at sts was tunning it Via email I had him set the trans settings back to stock and installed a shift kit. I now do my own tunning with efi live.

 

According to AllData.......

DTC P0748

Circuit Description
The pressure control (PC) solenoid valve is an electronic device that regulates transmission line pressure based on the current flow through its coil winding. The magnetic field produced by the coil moves the solenoid's internal valve which varies pressure to the pressure regulator valve. The powertrain control module (PCM) controls the PC solenoid valve by applying a varying amount of amperage to the solenoid. The applied amperage can vary from 0.1-1.1 amps. Low amperage, 0.1 amp , indicates high line pressure. High amperage, 1.1 amps, indicates low line pressure. The duty cycle of the PC solenoid valve is expressed as a percentage of energized ON time. Zero percent indicates zero ON time, non-energized, or no current flow. Approximately 60 percent at idle indicates maximum ON time, energized, or high current flow. The PCM determines the appropriate line pressure for a given load by comparing the throttle position sensor voltage, the engine speed and other inputs.

When the PCM detects a continuous open or short in the PC solenoid valve circuit, then DTC P0748 sets. DTC P0748 is a type C DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:
DTC P0748 Pressure Control (PC) Solenoid Control Circuit

Conditions for Running the DTC


The system voltage is 10 - 18 volts .
The engine is running.
Conditions for Setting the DTC
The PC solenoid valve duty cycle reaches its high limit, approximately 95 percent, or low limit, approximately 0 percent.

Action Taken When the DTC Sets


The PCM does not illuminate the malfunction indicator lamp (MIL).
The PC solenoid valve is OFF.
The PCM freezes shift adapts from being updated.
The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
The PCM stores DTC P0748 in PCM history.

Conditions for Clearing the DTC


A scan tool can clear the DTC.
The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

DTC P0748 may set under low voltage conditions caused by high electrical system demands.

 

do you think that b/c rick at STS turned up the line pressure and I'm now running a built trans with a shift kit that there's to much line pressure and that's what is causeing this code to keep happening.

 

DO u have a higher stall TC in it. Its pretty common with a stall

If its setting the cods every time you drive it, Its probly a legit code. Mine would set it every 5 times or so I would drive the truck. Yes it can be turned off in the tune, just make sure its not a legit code...

 

Yes I had him put mine back to stock and the code quit setting. I watched the pc solenoid amps with a snap on scanner and whenever they went below .1 the code set. I could set the code when brake stalling the truck. Get a transgo hd2 shift kit installed then have him put the trans presures back to stock. I think it would set the codes with a stock trans also being the p0748 is a circuit code.

 

Oh yes, get that line pressure dropped back to stock! You are supposed to be at stock line pressure when running a shift kit. The reason you bump line pressures up is to increase shift firmness on a stock transmission, but a shift kit eliminates the need for a higher pressure. With the exception of shift points and such, most of your trans settings should be stock with a built transmission.

 

ok thank you I'll try put the line pressure back to stock and see what that does .