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


67barracuda4u
04-17-2007, 01:20 PM
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 :banghead: ..Then i replaced the throtle body, 220 no fix:banghead: ....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
04-17-2007, 01:22 PM
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
04-17-2007, 05:19 PM
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
04-17-2007, 11:06 PM
ok, thanks will post that up tomorrow...i will try to see if i can get a voltage meter..thanks

67barracuda4u
04-18-2007, 12:43 PM
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
04-18-2007, 08:54 PM
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
04-19-2007, 01:21 PM
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
04-19-2007, 01:39 PM
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
04-19-2007, 01:44 PM
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
04-19-2007, 02:35 PM
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
04-19-2007, 02:38 PM
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
04-19-2007, 03:49 PM
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
04-19-2007, 04:11 PM
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
04-19-2007, 04:50 PM
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
04-19-2007, 04:54 PM
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

2000CAYukon
04-19-2007, 04:56 PM
Glad you found it, ignore my last post.

You should be able to find a plug at any acdelco parts store.

//2000CAYukon

67barracuda4u
04-20-2007, 01:28 PM
Thanks 2000CAYukon, i think i found the problem it was that harness i told you that plugs into the tps..i got some connectors yesterday and will be trying them right now to see if that will solve the problem...thanks i ll keep you posted...

67barracuda4u
04-20-2007, 02:03 PM
Well, i guess i was wrong, i just plugged the harness inn right now, and at first it did look like it worked but i guess as it got warmer the rpms still went down, and did the same thing, i will be taking a look at your post though, so i can try to find the negative..where is it ussually located at...thanks 2000CAYukon sorry for the bother, i was just so happy i though i had it solved.

67barracuda4u
04-20-2007, 02:06 PM
Oh, yea, the ecm i have is Serv # 16146299, which i just called this guy here at the local ac delco store and they told me the silverado did not come with that ecu...but that is the one i have in there right now, and that is the one that its always had... I see 2 ground wires at the thermostat housing area which go to the alternator,a sqaure black sensor type next to the valvecover, and another accesory ground..

67barracuda4u
04-20-2007, 02:13 PM
another thing i forgot to mention..When i had my headers installed they did not install the o2 sensor, which is now unplugged..they did not install it because the headers had to hole for it to go inn.

2000CAYukon
04-20-2007, 03:14 PM
Well, I just checked the internet for that ECU number and it does look like a valid ECU for your year. See http://www.cruzers.com/~ludis/c3xref.html#16146299

With your 02 unpluged, you will always be in open mode so you need to get an 02 bung welded to the header. Any muffler shop should be able to do this.

How did you install the new connector? Did you cut the old one off and then crimp or solder the new one?

//2000CAYukon

67barracuda4u
04-20-2007, 04:59 PM
For now, i just crimped the plug in there, but after done with it i will be soldering it..Well, yea, thats does sound like the ecu from my silverado, what does that OPEN mode mean, is that a reason why my ecu is acting up...also everytime i check the ecu with my scan tool, and it displays the code, with the scan tool on the truck seems to function correctly, the rpms go up and it does not shut off when you move the steering, but after you turn off the Scan Tool the rpms go down, im guessing it is a bad ecu, might be going to get one this week end..thanks let me know on that Open mode thing, i will also try to get the 02 bung welded in after i put the new exhaust inn..thanks once again

2000CAYukon
04-20-2007, 05:07 PM
For now, i just crimped the plug in there, but after done with it i will be soldering it..Well, yea, thats does sound like the ecu from my silverado, what does that OPEN mode mean, is that a reason why my ecu is acting up...also everytime i check the ecu with my scan tool, and it displays the code, with the scan tool on the truck seems to function correctly, the rpms go up and it does not shut off when you move the steering, but after you turn off the Scan Tool the rpms go down, im guessing it is a bad ecu, might be going to get one this week end..thanks let me know on that Open mode thing, i will also try to get the 02 bung welded in after i put the new exhaust inn..thanks once again

For starters, read this http://www.customefis.com/GMEFI.html

Closed loop is when the ECM is reading the 02 sensor and making adjustments based on feedback from them. Open loop means it is reading a table in the PROM.

I can't remember from memory what happens when you hook up a scan tool but it may disable the EGR (again not sure here).

Are you sure there are no vacuum leaks? Have you checked EGR and solenoid?

I will not be home until really late tonight but I will take a look at my 90 manuals to see what happens when the ECM is put in diagnostic mode.

//2000CAYukon

67barracuda4u
04-23-2007, 02:56 PM
Sorry, YukonCa2000 for not responding in 3 days..i just been very busy trying to fix the truck, i went out and got another ecu from the wrecker and the truck did not really like to idle at all..also what you are saying about the o2 sensor is right...i will try to make the o2 bung myself later today...also i will try to recheck all the vacume lines, but with 2 attemps on different engines, it sound unlikely id make the mistake twice.. i will get back to you when i get somekind of positive response from the truck if any..thanks

67barracuda4u
04-23-2007, 03:22 PM
ok, i see now i understand the fuel managment system..it could be becuase of the o2 sensor..i will take off the exhaust system right now and install the 02 sensor bung...does it have to be in the header...can i put in in the collector...thanks

2000CAYukon
04-23-2007, 03:30 PM
ok, i see now i understand the fuel managment system..it could be becuase of the o2 sensor..i will take off the exhaust system right now and install the 02 sensor bung...does it have to be in the header...can i put in in the collector...thanks

As far as I know, it needs to be before the cat (not sure if you have one or not). I think that most muffler shops will know where to weld it and I think the collector is a good spot.

Good luck. Also note that once the 02 is fixed, it may take a few days for the ECU to relearn fuel trims.

//2000CAYukon

67barracuda4u
04-23-2007, 10:15 PM
Ok, thanks once again, i appreciate your help, allot..it seems you know your stuff man, keep up the good work, i will try to go to a muffler shop to see if they can weld that for me.. I will keep you posted on my progress within the next couple of days.

67barracuda4u
05-05-2007, 09:03 PM
Hey, i finally got the o2 sensor bung in there, have fixed the exhaust allready, still does the same thing, im guessing it is the ecu, will probably get another one..thanks

2000CAYukon
05-06-2007, 12:05 PM
Hey, i finally got the o2 sensor bung in there, have fixed the exhaust allready, still does the same thing, im guessing it is the ecu, will probably get another one..thanks

When you say "still does the same thing", are you referring to the TPS issue?

Note that it can take a few trips for the fuel trims to adjust once it starts going into closed loop.

Can you post what the scan tool is seeing now?

//2000CAYukon

67barracuda4u
05-07-2007, 11:20 AM
well, i installed everything up, sounds great but it still dies when you turn the steering wheel... i checked the ecu and it still says open loop status..like you said maybe it still needs time to adjust.. should i leave the truck on for a few?...thanks for your help.

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