code 22 tps voltage low?

[adam74]

http://www.troublecodes.net/GM/89-90_57k/

well code 22 according to this^^^ but it was linked for 88-95 5.7s. first I guess I need to make sure thats the right code for the number, had 12 and 22 for counting flashes with the paperclip. if so Im assuming thats the throttle positioning sensor? just trying to make sure I fix the right thing here. took it to get inspected and of course it didnt pass texas emissions. the ses light wasnt on until on my way home after they tested the emissions. I have a 95 tahoe 4wd with the 350 tbi
the guy that did the test stated that the truck was dumping too much fuel into the tb based on the numbers he got from the computer.

 

[lesterl]

code 12 should blink out 3x followed by any other codes 3x each, ending with 12 3x more rinse repeat.

You need to put a meter on your wires comming out of the TPS one end to ground the ignition on (not running), probe all 3 wires going into TPS, one should have around 0.5vdc on it, another 5vdc, and another 0vdc, if any of these are gone then inspect wiring, if the 0.5vdc is low it can cause the code (throttle position sensor needs to be adjusted to get within spec.)

 

[adam74]

Right I got 12 three times and then 22 three times then repeated those two. Was just trying to make sure the 22 code is for the tps and maybe see if someone knows how to test it.

 

[lesterl]

Like I said on testing TPS, 3 wires, if wiring is good you should have a wire with 5vdc, one with 0vdc, and the other will vary from about 0.5vdc to 4.8vdc (this of course with the ignition on) also run the throttle open and shut to see an even increase and decrease in the voltage on this wire. If all checks ok, then TPS is good.

 

[adam74]

ok thanks man. sorry was half asleep when I read it this morning lol.

 

[lesterl]

Thats ok, let us know how it tests...

 

[adam74]

will d. get to it this weekend.

 

[adam74]

tps tested out good. throttle cable did have a little catch in it every now and then. read that was a possible cause for the tps code so sprayed some wd40 in it as best i could. that should take care of it. here's a link I found-

http://easyautodiagnostics.com/gm_tps_test/pickup_van_tps_1.php

 

[lesterl]

That is a good troubleshooting article, I dont think it applies in your situation. Either your throttle stop is set too low (idle reading) or your tps is opening, or the signal line to the pcm is opening, or the 5v feed is grounding/ failing.. (low voltage signal to PCM), a sticking cable will present a higher signal to PCM (throttle not closing all the way).....

 

[adam74]

well all the numbers matched up with the article when testing the voltage on each step. I think I had also found a vacuum leak so I put a clamp on the pcv tube. that actually made the truck run alot smoother throughout the rpm range when driving. it idles alot smoother also but did notice the rpms are closer to 500 at idle with no a/c on. I'm thinking that is a little low shouldn't it be closer to 800?

 

[lesterl]

Automatic is 650 in gear IIRC.... What is TPS voltage at idle?

 

[lesterl]

BTW your tachometer may be off.... mine on my 98 reads 400 rpm in gear at idle when hot (scantool reads near 650...)

 

[adam74]

I didn't check it while running, that I remember, just with the key on/motor off like the tests said to do. I can check that tomorrow. do I check the blue wire and a negative while it's idling?

 

[lesterl]

voltage not running should be fine as the source is regulated inside the PCM.... What did it check out at in the idle position?

 

[adam74]

5 volts. Believe the test said had to be within the 4.5-5 range

 

[lesterl]

We want the voltage on the signal wire, the 0.5-0.9vdc range....

 

[adam74]

Ok I'll have to check it again tomorrow. Cant remember if i checked that or what the number was