98 dodge ram 1500 5.2

Check engine light was on. the truck wouldnt run right or even start sometimes. The shop told me that it was the TPS. Now heres where it gets odd.

When the AC compressor switch is turned on it causes the voltage to drop to the TPS. They said that the 2 are not connected and it shouldnt be happening. So they have no idea where to go from here. They said they can start replacing things, like the PCM, but it might not be it and just end up costing me more money. I have them disconnecting the AC compressor switch and i'll lose AC and defrost but atleast the truck will run.

any ideas on this one. They called a few dealers and nobody has ever heard of this happening before. i'm to the point where i'm gonna have to rip things out one by one and thats gonna get pricey

 

short somewhere in the wiring. I'd check all your grounds first. Then find out where there might have been a lot of heat exposed to the wiring harness. That may be a point of electrical bleedout if the insulation on the wires stiopped working....

 

the ecm looks for spikes in tps voltage to shut the ac off under full throttle so in a way they are connected. might want to start with that. Check the grounds!!!!!!