help with 92 silverado idle/T.P.S sensor problem please help

[67barracuda4u]

It has been a couple months now since i havnt used my 92 silverado, about 3 months ago my silverado started acting up, first off you start the truck, and it kind of idles too low.. I was told it was a bad t.p.s sensor, throttle possitioning sensor, i replaced it twice new, and no fix ..Then i replaced the throtle body, 220 no fix ....Well the list goes onn and on..the symptoms are when you start the truck and it idles low aprox 500-800 rpms and you move the steering wheel and as it draws power from the engine the rpms go very low and eventually killing the engine, i have asked people from chevy dealers and they suspected it would be a wire that was rubbing on and might of taken (-) negative draw from the ecu, but i noticed that everytime i unpluged the T.P.S sensor when the truck was onn, and then plug it back inn, the rpms went up and wouldnt die when i moved the steering wheel, it will work like new but after i shut off the truck and restart it, it will do the same thing, i have to unplug the t.p.s sensor back and start again, does anyone here know what it could be..oh, yea i put a scanner on the ecu and it says T.P.S sensor voltage too low.. how can i fix that

[67barracuda4u]

Oh, yea, i allready went through putting 2 engines which were rebuilt, and it seems to do the same thing with each of the engines..

[2000CAYukon]

The TPS uses a 3 wire connection. One is a reference voltage, another is the ground and the last is the value of throttle position.

Using a volt meter. Measure the voltage of each wire and you should be able to figure out which one is the reference. One of the other 2 should be the ground so check to see if you have a good ground connection.

The reference voltage should be 5 volts.

It would also help if you post the other information that was collected when it was scanned.

//2000CAYukon

[67barracuda4u]

ok, thanks will post that up tomorrow...i will try to see if i can get a voltage meter..thanks

[67barracuda4u]

Hey, here is the info i got from a scan tool diagnosis...

Code Present: 022

air dvrt. sol DIV
air sw sol conv
batt. (v) 13.6
engine rpm 875
ide req. rpm 850
loop status open
map (v) 1.49
tps sensor (V) 0.45


i will get a multi meter today and will post the numbers up when i try it...this is of the truck when it is running at idle...when you move the steering rpms drop to 700 thanks

[2000CAYukon]

Originally Posted by 67barracuda4u

Hey, here is the info i got from a scan tool diagnosis...

Code Present: 022

air dvrt. sol DIV
air sw sol conv
batt. (v) 13.6
engine rpm 875
ide req. rpm 850
loop status open
map (v) 1.49
tps sensor (V) 0.45


i will get a multi meter today and will post the numbers up when i try it...this is of the truck when it is running at idle...when you move the steering rpms drop to 700 thanks

This says that you were in open loop and it does not show the coolant temp; however, it may be in open loop because of the code 22.

22 is low voltage which means the reference voltage was bad, ground was bad, TPS voltage back the ECM has a bad wire/connection, TPS is bad (doubt it if you replaced it twice) or the ECM is bad.

//2000CAYukon

[67barracuda4u]

Well it did actually tell the coolent temp and other info, here it is again

batt v 13.6
engine rpm 875
coolent temp 120
esc counter 192
exhaust 02 moves from rich to lean and back and forth
fuel pump v 13.6
iac position 73
idle req. rpm 850
loop status open
map v 1.49
02x MV 448 and goes up
o2s crosscnt 158t
prom id 5731
tps sensor (v) 0.45


Now i just checked with a volt meter and this is what i got.. there are 3 wires on the tps sensor, one yellowish has 05.0 volts the other which is blackish brownish has 00.5 volts...and the black one seems to be neg..now this is after i turned the truck disconnected the tps sensor and reconnected..here are the numbers when all in normal, meaning when i turn the engine on without disconnecting the tps sensor....which is normally when it fails to raise the rpms......Now i just tried it in the normal way, which is without disconnecting the tps sensor and the voltage on the tps sensor on two of the wires which are the 2 close together...is the yellow same volts as last check and the wire next to that one is still the same...Except when i tried to check the neg wire on the plug with the yellow wire and the harness unplugged that raised the rpms on the engine without the plug being hooked up to the tps..i now know it is definitly a neg issue since all other wires are good..

which the plug look like this....

_____
Black/brown wire -----> |* * | <------ Yellow wire 05.0 Volts
.05 V -- --
|*| <-------black which seems to be neg.



now in this case what can i do to fix that should i attempt to put a negative wire down to that plug...also i have changed the tps sensor, purchased one new at the autozone here, didnt fix the problem...so i went to the wrecker and bought another one, and still nothing, now i know it is not a sensor issue but a negative, because when i tried the neg and the yellow 5.0volt wire in the harness with the leads of the volt meter the rpms went up...thanks allot

[67barracuda4u]

Hey, another important thing i noticed was when i was logging inn to the trucks ecu using my scann tool, i noticed that when i was about to read the code erros which is the 022 code, just as i was doing that the rpms went up, also when i logged out or disconnected the scan tool, the rpms droped, i tried this about 4 times and it happened all the time.. i will try to check the negative on the ecu but need to know first it is has any negatives that go there on the ecu, or is the main negative somewhere else on the truck.. Thank you very much 2000CAYukon atleast i know whats causing the problem now...finally the feeling of using my truck once more, hopefully i can fix it by this week end.

[2000CAYukon]

Sure sounds like a bad ground to the TPS. Could be the wire itself. You need to track where the black wire goes. IIRC, the ground for the TPS is on the intake.

I can take a look at my 90 manuals but I won't be home until 9 PM Pacific time.

//2000CAYukon

[67barracuda4u]

Thanks once again 2000CAYukon....Well i just unhooked my ecu, and batt...i have traced the 3 wires, it was actually on gray blue and black...

# on ecu input harness

gray 14
blue 13
black 2

well i traced them all back in to the main harness that plugs into the ecu..using a small voltage battery, i hooked it up to the tps input connection first the blue and gray, then over at the ecu input harness i checked the 2 wires for a voltage which was carried through the wire from the bat, they read out good...i then tried the black and gray and same thing, i now know where all three wires are located at, but still cant figure out the bad neg connection..

[67barracuda4u]

could it possibly have a negative connection that is grounded to the body of the truck and goes to the ecu, sometimes most vehicles have them like that dont they...also when i told you that i checked with the volt meter leads, one on the gray and another one on the blue, that caused the rpms to go up...maybe its a bad ecu..

[2000CAYukon]

It could be a bad ECU ground or an internal issue with the ECU ground with black #2.

On my 90, the ECU ground is at one of the intake manifold bolts.

Good Luck,

//2000CAYukon

[67barracuda4u]

Ok, i agree with that too, that neg from the intake, where does it go to...i looked at this image right here on this website http://www.gearchatter.com/viewpost13125.php

and i now need to locate the PCM power train control module to find the ground...if this is the one your talking about then we are right...also as i keep on rethinking the stuff it does, i keep on thinking it is not the ecu, but just a neg cable..now i need to locate the negative sensor ground on the pcm to find out..thanks

[67barracuda4u]

i found the problem, not the ecu not the ground, it was the plug...i tried removing it, and i noticed that when you jiggled it, it lost contact...so i will try to get a new plug today, thanks for alll your help guys...keep it up.

[2000CAYukon]

Not sure which ECM (or ECU) you have in your 92. On my 90 it is a 1227747. Here is a diagram that shows the system ground for the 1227747. See http://www.wedgeparts.com/images/747ecm7.jpg

Both Pins D1 and A12 are ground at the intake manifold at the tstat housing. The 02 sensor ground is also in that area.

You really need to see which ECM you have and then we can figure out which pin(s) is the system ground.

Also note that if you had an issue with the system ground for the ECM, you would probably have lots of issues. You should still make sure the grounds are good.

//2000CAYukon