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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Have a 89 Firebird TBI Base model 5.0, getting a check engine light after driving 20-30 miles, highway or around town. Also noticed the last time I filled up after pumping a gallon or 2 it clicked off, it did this a couple times till filled. Reading through threads this all points to the evap canister. Ive benched checked the solenoid on the canister (good) also checked power at the solenoid plug using both the plug ground and a chassis ground with the key switch in the on position (all checks good) I don't have a vacuum gauge but just sucking on the input and output vacuum with the solenoid closed or open it holds or opens. I've replaced the vacuum lines ( with vacuum line) throughout that system. I checked the Pop off valve ( looks like a shower head) close to the tank, it pops off just blowing into it, not easy but not hard either. I've tried blowing through the steel line that runs from the tank to the canister, I don't think it's clear. Is there a restrictor in that line that could be plugged? If so is it in the tank? Thanks in advance for the replies , this is an awesome site.
You had me there for a minute sofa kingdom. Question through the replies from ULTM8Z, it listed 2 terminals, A-B or A-M. I didn't see , or maybe i missed it. Does A-B (5-6) apply t o certain years / Same for A-M (6-12)?
Any other way to determine if the ECM is faulty? Got power to the solenoid no problem. checking the ground wire (gray 435) to ECM it shoots good for continuity. Troubleshooting/ diagnostic for code 32 says repair open CKT 439, if not open it is a faulty ECM.
The solenoid has 12V on the pink/blk wire at all times when the key is on; then the ECM grounds the other wire to operate the solenoid.
Probably nothing wrong with the ECM.
You should see about 12V on that other wire whenever the key is on and the solenoid ISN'T being commanded to turn on, and 0V (ground) when it is. A "continuity" check isn't the right test.
Also if you can identify the wire at the ECM connector for the ground side of the EGR solenoid, then turn the key on (engine off) and ground that wire to bare metal somewhere on the car (using a jumper wire... just ground one end to chassis and use the other end to carefully touch the terminal on the ECM connector). You should hear the EGR solenoid click on and off as you touch and remove the jumper wire.
You can do this test before or after the test Sofa suggested (by unplugging the solenoid connector and putting a DMM on it), but both tests need to be done.
If Sofa's test shows that you're getting 12V on the other wire and my test shows that the ground wire activates the solenoid, then it could end being the ECM after all.
Want to thank you for your assistance with this. I purchased a pontiac service manual for this, that's what i've been using as far as troubleshooting tree and wiring diagrams. I'm sure they are all closely related with subtle differences. What i've found is key switch on good power to the b side of the solenoid, the manual wants you to use the A side as the ground /gray wire, no joy there. If you test for power on the B side pink/blk and go to chassis ground you have power. I cannot establish a good ground using the gray wire. The gray wire from the solenoid to the ecm has good continuity. And yes with key switch on, using a meter or the light and going from the gray wire at the solenoid and connect to chassis ground you get light or voltage. Finally i applied power and a ground to the solenoid by itself and it works. Am i missing something, I still think it's the ECM . i removed the ecm to check the plug ends and the ecm side and all look ok. tried pushing on the plugs, then the wire at A4 on the ecm to ensure it is making contact. I'm even thinking of putting some conducting material (foil) between the male and female connectors to see if that will work. Thoughts?
The gray wire is grounded ONLY when the ECM grounds it, which it does ONLY when it decides that it's time to operate the solenoid. The rest of the time it is NOT grounded. Testing "contnuity" is NOT the right test for this. It's just basic electricity, as taught in middle-school science classes and whatnot.
thinking of putting some conducting material (foil) between the male and female connectors to see if that will work. Thoughts?
I see what you're saying. reading the circuit description for when the ECM checks EGR operation. At least I know the circuitry is good for the solenoid and it works. I'll check the EGR valve itself , vacuum , lines and look at the MAP sensor parameters. And yes I have 2 DMM's Although if you look at code 32 for 5.0 VIN E "F" Carline (TBI) the way it reads in the checks it sure sounds like the ECM should be providing a ground while doing theses tests, especially step 3. Disconnect EGR electrical connector/ connect test light between harness connector terminals, I see that as A & B on the plug side / Ignition on engine off / test light should light. Is n't that saying the ECM should be completing the ground? Just trying to understand
Not familiar with the troubleshooting charts nor to the details of TBI emissions eqpt so I can't answer specifically to that. However if it says the test light should light at that time, then that would seem to mean that the EGR should be getting commanded at that time. Test light lighting = the same thing as the solenoid being operated. So if the solenoid is supposed to be operating at that time, then yes, it fits the definition of "ECM commanding the EGR on".
You should be able to hear the solenoid click when it gets turned on.
If you find the ground wire at the ECM, this is what I was suggesting. Remove the plastic retainer and you'll get access to the back of the terminal.
I used a scrap connector in my garage to simulate it. You just have to locate the correct terminal via the engine wiring schematic. The other end of jumper wire would be grounded to chassis someplace.
With the 12v energized with the key on, you should hear the solenoid click when you ground out the ground side of the circuit.
I found the A4 terminal, unplugged it, inserted a small cotter pin, reinstalled plug, turn key on and grounded it using a jumper wire. The solenoid worked, turned off when ground was removed .
Ok, so you just proved out the EGR solenoid and the wire harness. Maybe also visually inspect the EGR connector and ensure it doesn't look like a bad connection that could cause an intermittent.
I guess the last thing you can try is to hook up a light between 12V and using the ground wire jumper. Then when you're driving, see if that light ever comes on.
The ECM I believe needs to see a certain TPS% and intake air temperature to determine when to turn on the EGR. So if those sensor are good and the EGR is still not turning on, then I suppose it could be the ECM.
It's usually a failed diaphragm on the egr valve... first test that your egr opens with vacuum. Easiest to use a hand pump connected directly to the inlet port.....
09-24-2023, 09:46 AM
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. Question through the replies from ULTM8Z, it listed 2 terminals, A-B or A-M. I didn't see , or maybe i missed it. Does A-B (5-6) apply t o certain years / Same for A-M (6-12)?
Although if you look at code 32 for 5.0 VIN E "F" Carline (TBI) the way it reads in the checks it sure sounds like the ECM should be providing a ground while doing theses tests, especially step 3. Disconnect EGR electrical connector/ connect test light between harness connector terminals, I see that as A & B on the plug side / Ignition on engine off / test light should light. Is n't that saying the ECM should be completing the ground? Just trying to understand 
