I installed an LS2 throttle body on my 2005 5.3 truck with an adaptor harness. Now the truck won't start and I get reduced engine power. I found out something about a TAC module conflict, but should the truck at least start and stay at idle. I am trying to rule out other problems. Can someone point me in the right direction.

 

Looks like you have two chioces,1)purchase a 2002 tac module and get it to work with 80-85 % trottle opening.Or 2)contact DRX and purchase a different wiring adapter that has a 5 volt ref jumper attached to get proper
trottle blade operation(mine works GREAT!
I dont believe there could be any other thing wrong if that was the only mod done pefore the REP started.
Good luck.

 

Who is DRX?

 

member on t.his forum

 

Will the TAC module conflict cause my truck not to start at all?

 

YEP!
Quick fix?gm#12574221

 

The above # will get you running but throttle blade will only open 80-85%,cost is about 135.00 w/s price at your local dealer list is 215.00.
I have one I could sell you cheap!I have already changed over to the new harness from drx.tried looking for the # cant find it right now.I take paypal,and can ship overnight if you want.

 

Here is an excerpt from the shop manual. The PCM can take one of several actions depending on the seriousness of the Throttle Actuator Control(TAC) system error encountered:

"Reduced Engine Power Mode
When the PCM detects a condition with the TAC system, the PCM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:

• Acceleration limiting--The control module will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.
• Limited throttle mode--The control module will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.
• Throttle default mode--The control module will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
• Forced idle mode--The control module will perform the following actions:
  • Limit engine speed to idle by positioning throttle position, or by controlling fuel and spark if throttle is turned off.
  • Ignore accelerator pedal input.
• Engine shutdown mode--The control module will disable fuel and de-energize the throttle actuator. "

For one thing, your dual TP sensor signals will now be moving in opposite directions. But the truck PCM is expecting to see them moving in the same direction. So the PCM will have no clue where the blade is at. I'd say that could cause a shutdown. Particularly if one of the signals was indicating WOT when the PCM was commanding minimum throttle.

Not that there couldn't also be something else wrong. But the TP signals definitely have to be corrected.

 

Thanks for all your replies. Very helpfull info!!

 

On my Ls2 intake swap I used the LS2 injectors and I used some pigytail adaptors. In the intructions it read that the wires did not have to be connected in any specific way since they only energize the injector. Is there a specific way to connect these wires. I know that there is a common pink on the pigytails and the truck wires.