I have started to have a lot of trouble with the throttle position sensor's circuit. I say circuit because I am totally stumped on what it could be. Here is the problem: I drive or sit in park while monitoring everything with tunerPro. I get very false readings from the TPS. I will have the gas pedal/throttle totally not moving and recieve a reading that will fluctuate all over the scale. I have had it sitting at idle and give a voltage reading of .55 to .00 to 2.3 to 4.3 back to 1.5. And that is all in the course of 1-2 seconds.

I have set the minimum voltage reading many times. I have replaced the old sensor with a new sensor. Both read good with a DMM though. I have followed the wires all the way back to the ecm and found nothing bad. I have tried it on 3 different 730 ecms. I recieve no ses codes. Please do not post the 'How to set min. TPS voltage" article. Where should I go from here?

Just went out and double checked all of the voltages with a DMM. I do get a 5 Volt reference signal, I get the correct voltage at WOT and closed throttle. I get the correct voltage from the black lead to the positive battery terminal. also the correct voltage across the black to blue lead.

 

As a quick test, run an auxiliary ground from the TPS back to the ECM ground. I had a similar problem once. It was a bad TPS & a bad ground simultaneously.

 

I am not sure what you mean by auxillary ground from the TPS to the ecm. I checked the voltage at the ground wire it shares with the IAT sensor and it came up good.

 

I mean running a wire from the black wire at the TPS back to the ECM. If you're running the 305 TPI ECM, it should be a black wire at connector B6

 

For the most part the problem seems to have started overnight too.