First off I’m was a dealership technician for CDJR. Not working there now but I might find another dealership to work at. I have a 2003 Ram 2500 with a 5.7 Hemi and the throttle body won’t respond from input from the accelerator position sensor. I bought the truck for $2500 and it wasn’t running properly. It had a runaway idle. I found the intake manifold was broken and leaking air. So I replace the manifold and gaskets and found it only running on 7 cylinders. I removed the valve cover and found a broken valve spring. So I replaced both heads. After installing them I realized the throttle was not working. I did a visual inspection and checked for open connections in the wiring from the app and the Tb and the pcm with my multimeters. Checked for corrosion and bent or broken pins and found nothing wrong. I decided to replace the app sensor but it didn’t fix it. Next I replaced the throttle body but it still didn’t fix it. The diagnostic information from dodge led me to believe the pcm was the culprit. I sent it out to have it tested and was told it was damaged and could not be fixed. I bought another pcm used and used the DRB (Chrysler scan tool) to program it to my truck. Then I started it and it still didn’t fix it. If I relearn the throttle body with the DRB function the throttle body will work until I start the truck. Then it stops working. I tried to disconnect sensors on the engine thinking one could be shorted out and causing my problem. But this didn’t fix it. I performed another visual inspection. On the wires under the truck near the transmission and the wires in the engine bay and couldn’t find any problems. I’m at a loss. I don’t know what else to do. Does anyone have any ideas or have heard of this problem?

 

DRB should be able to tell you what pedal position is, and also what it thinks throttle position is. It's gotta be getting bad information from one of the two.....

 

I have a video of me doing the test not sure if the voltages are correct but the throttle body is working. As soon as I start the truck it no longer works. The video won’t upload for some reason

 

I don't think we host videos here....... Put it up someplace like youtube, or similar, and then just link to it here.

 

Try this :

 

Bump...

 

It looks like it is working just fine..... until you start the motor???

 

Unfortunately I don’t have access to the DRB and Witech anymore but if I would clear the codes and perform the relearn procedure it would work and also when I performed the test in the video it would work but yea as soon as you start the truck the throttle body stops working. I wish I knew which direction to go in to fix it I’ve tried so many things

 

I don't know a lot about those systems..... I am real curious what the difference is between engine running, or not...... Alternator output is the only thing I can think of. Is there a short to voltage somewhere??

 

I also have an 05 1500 hemi and I swapped the known good battery from that after reading your reply. Also if I connect the battery terminal after disconnecting it with the key on I noticed the throttle body blade will move from the closed position. But it only moves with input from the pedal if you have the DRB connected and perform the relearn. Like I said though if you start it it no longer works