southern78

I cannot get it to run unless I give a some gas then it ifles horribly. The only code I am pulling is Code 21 which I think relates to the TPS voltage.

But if I let it try to idle and just kills itself.

Any suggestions?

thanks,
Howard

Guest47904

Start with the obvious. Key on, back probe the TPS to see if the grey wire has 5 volts referenced to the black wire. Then see if the blue wire varies from about .5V to 4.9V when you swing the throttle plates from closed to WO. Your fault indicates the blue wire is not going below 2.5 volts. If that is the case, Disconnect the TPS and check the voltage on the blue wire. If it's not at or near 0V, chances are the blue wire is shorted to a voltage source. The hard part will be finding the bad spot. Luckily the blue wire only goes from the TPS to the PCM if that is the case.

If it goes to 0 when disconnected then the problem is inside the TPS. Be sure to check the plates to be sure they are closing properly.

southern78

Thanks speedy, will check when I get off of work.

Apperciate the response.

Howard

Injuneer

DTC-21 = Throttle Position (TP) sensor circuit (signal voltage high)

I thought that set when the TPS voltage exceeded 4.90V????

southern78

Ahh found a wiring issue. I have a custom setup and the motor is actually in my S10. I had gotten backfeed of voltage from a boost gauge some how. I corrected the wiring the voltage went back down and everything runs fine.

Thanks

Guest47904

According to the manual over 4.8V with KOEO, is one of 2 ways it can set. It also can set if it's over 2.5 volts at idle. Since the point in helping him was to see that it was not near zero, I took the safe route so I wouldn't have to explain that if it's less than 4.8 but not 2.5, it's still NG. Just trying to save some time and try to get one person on this board to check some things first BEFORE they go out and buy the sensor.

It is the 1994 GMP/94F-2 manual from Carline bought from Helms BTW.