I have a 1986 305 tuned port trans am and this morning the idle dropped to 500 when i wasn't giving it gas. It sounds very rough as if it might die.
I checked the engine codes and it was code 12, 22, 33, and 36. can anyone tell me what these mean and where to start??

Thanks, Grant

 

you might want to start with the low tps voltage first , hopefully this is just a bad ecm not a maf.

 

how would i find if it is the ECM? or the MAF sensor

 

go thought the trouble tree chart for code 22 at chevythunder.com

 

okay i have a few questions what does ALDL and SES stand for?

 

ALDL=Assembly Line Communication Link
Ses is the service engigine soon light also called check engine light or mil malfunction indicator lamp.

 

Okay I disconnected the battery and drained the energy out of the car and put out on learn mode I guess its called. But the only code now is just 22 but I don't really understand what I am supposed to do even after reading that troubles tree. Can you please explain in a dumb Ed down version haha?

 

Ok Ed I will keep it simple the code 22 is thrown when the ecm sees low voltage. This can be caused bye not enough voltage on the grey wire from the ecm it will be close to 5v with the key on or low voltage on the feed back wire the blue wire. The blue wire with the key on should be .54v dc and will increase without any glitches close to 5v at wide open throttle. Your problem can be a tps or wiring or bad ecm.

 

My coach called me Ed anyways so if I have proper voltage measured with a multimeter then it is the ECM if not than its wiring. Basically it right? Dang I sound dumb but i'm new to this haha

 

Oh and it was getting bad throttle response and it fixed that so it ain't the tps

 

On pin c14 of your ecm you should have close to 5v and almost the same reading at the tps grey wire. The blue wire at the tps should show .54v dc if the tps is adjusted correctly the same voltage will show at the ecm pin c13. All of this testing is with the key on. If all this checks out ok deoble check the ground connection behind the passenger cylinder head.

 

Okay I will check this tomorrow after school and let you know how it goes.

 

i found this random red wire by the ecm it goes through the firewall and ends it isn't supposed to be there I'm certain could this be the cause of the code and the idle?

 

It hard to see it may have been hooked up to the tach lead and ran under the dash at one time hard to say.

 

I looked a little closer and took it out and the red wire meets a white wire that runs into the harness and yeah it its tired into the tach part. Any idea what this could be?

 

some one had a tach in the car at one time. were you able to check the tps voltage ?
I just remembered another guy with a 86 had a low idle the memcal in the ecm is a aum.
https://www.thirdgen.org/forums/cool...ot-coming.html

 

Not yet I keep getting called into work early. I was going to do a continuity teddy then check the voltage.
But as soon as I can I will and what is aum?

 

teddy lol inside the cars computer is has a chip. there are letters on the chip called a brodcast code. The one marked aum has been known to have issues. But your throwing the 22 as well so you might want to resolve that first.

 

I just checked the signal at the tps and there was a grey that measured 5 volts a grey with a red stripe that was 4.5 and a black that was.21 volts. None of these changed while pressing the portal to the floor with the key on. any ideas?

 

are you sure your on the tps ? the top wire is black and is the tps ground. The center wire is blue the tps feedback to the ecm. The bottom wire is grey the 5v reference from the ecm.

 

Sorry it was .45 not 4.5

 

the black wire is showing voltage ?

 

Yeah on the left side of the throttle body I replaced it i'm sure it is the tps

 

the tps is on the right side of the throttle body.you should not be getting voltage through the ground. if you unplug the 3 plug harness and check for power on the black wire there shouldn't be any. it sounds like your new tps is bad.

 

I checked the actual writes and there are no wires going to anything near the tps on the right side just the throttle and the throttle spring i'm more confused than when I started haha

 

your confused with your right and left lol, all parts in your car are referenced s if you were sitting in the drivers seat.

 

Oh haha dang I suppose you were right calling me Ed haha. Anyways so if I am getting voltage from the black wire what does that mean?

 

the wiring color doesn't seem to jive ed lol, Im not sure if some one did a repair there at one time. the black wire is suppose to be a ground for the tps, mat,cts and gounds behind the passinger cylinder head.

 

I'll check the color deeper but three voltage means is not grounded properly?

 

if you pull of the cts connector and check the black wire for voltage its hooked to the black wire of the tps if you dont have power on the cts the 2 wires are not conected.

 

its sounds like there is something hooked to the ground wire or its shorted to power some where.

 

Alright grey is grey black is black and grey and red is actually ok so you ate still smarter than me note what?

 

Okay still with the key on?

 

yes still with the key on there should be no voltage there at all

 

It shows the same voltage as there is at the tPS

 

well grounds are not suppose to show power, I would leave the tps and cts unplugged . With the key on there is a 2 wire connector on the passenger side (right side) right net to the distributor the pigtail goes from the 2 wire pigtail to the mat under the plenum. Disconnect that and see if you have power on the black wire on the mat harness the wire thats running back into the loom.

 

So I can driver it without ether tps or that other hooked up?

 

no you need to figure out how power is getting to the ground

 

Cause I have to go somewhere soon I don't think I will have any more time today

 

oh ok slap it back together

 

Haha ok I'll work on it tomorrow thanks!

 

Okay the idle is doing it more frequently since I have messed with it could this mean that it is around the cts and tps?

 

And could I just tap into it and re ground it

 

you could tap into it and reground it but I was having you unplug the tps, cts and mat to see if as you unplugged one if the voltage went away if it did that sensor would have a issues and would need to be replaced.

 

I Brooke down yesterday cause my battery died and I was looking st my alternator and the ground on it was very very weak and I fixed out now it idles much better and three voltage on the ground its .02 instead of .2 like last time. could have been causing that this whole time?

 

12 SES light test. No eng RPM. System is normal.
22 Throttle position sensor circuit - signal low
33 MAF (Mass Air Flow) sensor - signal voltage too high
36 Ignition system circuit error.

You need a book that tells you the code meanings in detail with flow charts which tell you how to troubleshoot. Documentation is readily available on the net. The best book I've found is the GM factory shop manual, available for about $20. Just google it. I also have an engine code manual which gives good info about TPI cars such as yours, with good write-ups on each of the sensors. If you're going to work on it yourself I'd recommend building a library. It's not expensive.
With these computerized engines I believe you need good documentation to conquer them on your own.

 

I know it has been a while but I finally gt to check the mat under ether plenum and its the same exact voltage and unplugging it does not change voltage at the tps or the cts. So that means its wiring? Or possibly the ground? How do I go about checking The ground?