P0123 TPS High Voltage only with A/C On
 

2000 Dodge Ram 5.9l 4x4

Started the other day. Throws a TPS high voltage code any time the A/C is turned on. I can turn the A/C off and clear the code and it runs fine. Otherwise anytime the A/C clutch engages it reads 100% throttle on the scanner in Live Data and causes the code to reappear. The code can be thrown and I can turn the A/C off and the TPS begins to read within spec again. No continuity between the two connectors so I don't think it's back feeding.

Have read everything from bad ground, bad clock spring, bad PCM, bad Idle air control valve……..

Any direction or thoughts? I should be able to do any diagnostics needed just not sure where else to check.

Thanks!

If it is only when the A/C clutch is actually engaged, then either the control circuit for the a/c relay, or, the power feed to the compressor, is shorting to the tps signal wire. I suspect the only way you are going to find it, is by peeling open the wiring harness, and physically inspecting it.

Tps return voltage is less than 5 volts. If it was shorting with the compressor voltage (12V) i would think it might fry the pcm or at least disable it. Can you see tps return voltage with the scanner? If not i would check it at the tps with a meter just to verify voltage(both feed and return). Does the rpm do anything when the tps reads 100%