TPS issue

[mporte1983]

My son recently bought a 2003 Chevy Blazer 4 door 4.3 2wd for his girlfriend bone stock never tuned and it has this issue after hitting a large bump, the tps signal shows 10% tp with no throttle input which makes it harder to stop. We can turn it off and wait about 30 seconds and restart and problem is gone till hitting another pothole. I logged to see the issue happen but sadly did not save it. I have swapped out tps and idle air control valves and even the complete throttle body from his 98 Blazer and problem does not follow. I have continuity tested the wires and all is good. I wanted to try something this evening to see if I could replicate the issue without driving. so I started wiggling wiring around and bouncing the Blazer and nothing. my son walks over and sets his drinking cup on top of the ecm and boom the idle goes up and is stuck at 10% tp. I am suspecting it to be the ecm but before I go junk yard diving for an ecm wanted to get some thoughts from some other people. Thanks for any and all input.

[gtstorey]

Logs are automatically saved by date/time. You just have to dig to find them.

[blindsquirrel]

Have you tested wiring continuity while hitting a pothole? 'Tap test' on the PCM itself?

Spare a thought for the dealership guys facing problems like this on a daily basis and knowing that no matter how many hours they spend finding it, when they close out the ticket their warranty clerk in the front office will only flag it as WIRE AND/OR CONNECTOR REPAIR - 0.2 HR

By the way,

I have swapped out tps and idle air control valves and even the complete throttle body from his 98 Blazer and problem does not follow.

...would mean that the problem goes away after those components are changed. Maybe just worded wrong?

[TheMechanic]

Pull the PCM connector and using a flashlight make sure you don't have one of the female terminals on the connectors that is backed out. I have the male pins that I will insert for tension that I use on vehicles that have come from other shops that have given up. Often times crap mechanics will front probe with test lights and damage terminals enough to have no connection or intermittent connection but back probing will give a good test result. Happens more than you would think

[mporte1983]

Thanks for the advice, sorry for the delay been super busy. What I meant by the issue didn't follow was like when tracking down a misfire and you swap coils to see if the misfire moved. I swapped the throttle body from the 03 with the 98. I did a tension check and all pins checked out good. I have wiggled the harness and connecters and doesn't happen until I tap on the ecm and engine idle will increase and tps shows 10%. I will try to find time to dig through my log files to find it or make a new one next time she is here for a visit, last time I logged it was a few weeks ago and have tuned a few since then. I am trying to find a 2003 Blazer or S10 in local yards but not having any luck since this is the only year for those with a P59 from my knowledge. I have a 6.0 drive by cable compatible P59 on the shelf, but I am not sure if a write entire will do the trick.

[TheMechanic]

If you "Tap" on ANY module and data changes or there is any kind of change you either have a connector/terminal issue or a failed module.

[mporte1983]

Thanks, I am on the hunt for an ecu. Will update once I get it all done.