5v to APP and TB
5v to APP and TB I have a swap into a C10 from an 04:Tahoe. I'm getting no 5V to the pedal or throttle body. The TAC is good. I tested it in my daily driver and it operates the throttle as it should. I've traced the pedal wiring and the TB wiring and all are where they should be and all have continuity. I've also replaced all of that wiring with circuits from other factory harnesses that I have on hand. I have ign power to the TAC and ground to the engine in 3 places. Three different PCMs, 2 pedals and 2 throttle bodies. It all comes back to no 5volt from the TAC. PCMs have 5v on blue 7,45,46 and 48. 12v at Blue 19, 20, 57 & 75.
Teching In
Joined: Oct 2025
Posts: 12
Likes: 2
I have a swap into a C10 from an 04:Tahoe. I'm getting no 5V to the pedal or throttle body. The TAC is good. I tested it in my daily driver and it operates the throttle as it should. I've traced the pedal wiring and the TB wiring and all are where they should be and all have continuity. I've also replaced all of that wiring with circuits from other factory harnesses that I have on hand. I have ign power to the TAC and ground to the engine in 3 places. Three different PCMs, 2 pedals and 2 throttle bodies. It all comes back to no 5volt from the TAC. PCMs have 5v on blue 7,45,46 and 48. 12v at Blue 19, 20, 57 & 75.
When it was first built it drove about 60 miles first run. Next day......no throttle response. I have lots of parts on hand so I let him take a pedal, TAC, pedal to TAC harness, TB to TAC/PCM harness and TB. Nothing helped until the TB. It ran for several minutes with throttle response and he shut it off to go load a car. Came back and no throttle response again. It runs fine just no throttle. So now I'm involved and I've gone through all of the parts as I stated originally. Today I cloned the PCM from my daily driver that I've been testing the parts on. Even with that calibration, well, write entire it produces no 5v from the TAC.
I've setup over 200 PCMs for stand alone and never had anything like this. I've modified over 50 factory harnesses for custom installations and never had an issue. It's really baffling because of the initial start up and drive and the later brief success. The entire wiring for this circuit has been bypassed with factory wiring and still nothing.
No 5V was the result of a loose terminal in the fuse panel for the TAC fuse. So now the TB Homes when the key turns on and I have throttle response for a few minutes before it loses communication
