[MT-2500]

Originally Posted by pete44

Hello again..

Narrowed my rough idle problem to my TPS circuit..I shorted A and B together on DLC to check codes off ECM..Only showing code 22 (TPS Circuit Signal Voltage Low)..Which in fact ...It Is!

I first checked TPS connector for 5 volts with ignition key ON...GOOD
Then checked TPS connector between Blue wire and engine GND plugged into TPS..Read .05 volts..NOT .6 volts ..When I change my voltmeter scale back to proper scale it reads infinity (000)..When I go to wide open throttle it reads 4.0 Volts..

I am now looking at circuit itself.. The TPS wiring runs through firewall eventually to ECM.

What gets me about all of this is even the Chevy Dealer cannot look at this (OBD1) ECM system anymore!!! TOO OLD I GUESS

And by the way I have changed out the TPS already...

I'll trace/continuity check the TPS circuit to ECM..This still may be the ECM..Which I saw on a website I could get between 100 to 150 dollars.

Any suggestions appreciated!

Pete

Check the voltage readings to and from tps and then to PCM.