Tom400CFI

There is a VSS in the speedo itself that sends the Veh speed to the ECM. I doubt that it's relevant here too. I ran my CFI car (an '83 Trans Am) for years w/o the speedo hooked up. Threw a CEL, but ran fine.


.

Bigredwing

Thanks Tom. I just learned something new about my car! After a forum search I also learned how to access and replace the Vehicle Speed Sensor. Which now begs the question to the OP - how does the MPH your diagnostics shows in the log compare with your speedometer when on the road? If the log is wacko it could be more evidence of an ECM problem. It would be nice if somebody with a functional car could post their winALDL log for the OP to compare data. Maybe already covered somewhere but I did not locate it.

DUB

You have to verify that the voltage different is actually what you say it is. Use another method to verify this.

It can be loose wires or more than likely if it IS doing what you stated...it is internal in the alternator...more than likely the voltage regulator.

IF you actually are getting 18 volts...YOU HAVE SERIOUS SERIOUS PROBLEM And STOP cranking the engine with it like that. Major damage can occur.

DUB

lionelhutz

The WinALDL voltage data will come from a circuit inside the ECM which measures the incoming power connection and converts it to voltage data. And yes, it is basically used to adjust the pulse time of the injectors to compensate for the changing battery voltage effecting the injector opening time. Being a measure of the battery voltage, it should always be in the 13.5V to 14.3V range with the engine running.

You need to first determine if the alternator isn't working right and then move back to the ECM connectors and see if the proper voltage is getting to them, preferably checked with the ECM connected. I find it hard to believe the engine would keep running with only 5V reaching the ECM since the power supply circuits which provide the regulated power to the processor and other electronics would drop out and quit producing the correct output voltage with only 5V feeding them.

hugie82

This is a long shot but the air intake silinoid that operates the flap on the hood uses a lot of amperage when activated. It is activated by your TPS reading more than 75% open throttle. Check to see if that air door is open when your volts drop. A bad TPS could trigger it and mess up your idle or It could be just a bad alt/reg.

icpr4u

Thanks for the replies
I was checking the voltage at the battery and alternator today and found some interesting stuff.

Volts while running at the alternator 50...yup...50
volts at the battery while running- 12.1
voltage recheck showed a massive fluctuation at the alternator down to 4v
So I removed the battery and alternator to bring them in for testing tomorrow.

The red wire from the connector at the rear of the ALT seems to be grounded out. I have ZERO resistance between that connection and any ground wire / bare metal. That does not seem right.
I am assuming that comes into the cab via the fuse box right?
any ideas on what circuit. Just having a difficult time chasing it down.

Here's my guess:
The shorted or intermittently shorted circuit is sending mixed signals to the ECM. Maybe it's telling the car there is less power because some is lost in the short forcing the alternator to charge at too high of a rate. This is what is causing the car to chase it's tail in an effort to charge at the correct voltage. This also may have fried the ALT or voltage regulator and who knows what else.

Thoughts on my guess?
Please fell free to keep those great ideas pouring in!

Bigredwing- the speedo seems to be on point with what winALDL is reporting
Hugie82- I'll check tomorrow and see if that is involved at all

Buccaneer

The RED battery charge wire under the boot on alternator back runs down the loom on drivers side fender and then routes down through the drivers side, inside the frame rail all the way back to the battery compartment where it pops out and goes to the junction block. Hope this helps. A long time ago while my engine was out I went through every wire and connector to check them and found a couple issues with some connectors (one was the lower stater harness and the connector for the high side blower relay) and for some odd reason, someone had spliced that RED wire about a foot into the frame rail going forward. Ran a new RED heavier gauge charge wire. You would be surprised what you find when you go through everything in the electrical system. Hope this helps.

icpr4u

Buccaneer
This is just one wire without any splices or connections?

DUB

Well you obviously need the terminals that connect to each end of the wire. And this wire is encased in the black plastic split loom material also.

I am not at work right now where my 1982 manual is..... so I can not 100% confirm you you need to have a fusible link installed in this wire. 'Something' is telling me that you do need a fusible link in this wire.

The reason being....when a wire is run off the starter solenoid over to the alternator...THAT wire does have a fusible link in it down by the starter solenoid...so....logic would come into play and have a fusible link in that wire either back in the battery box at the junction block...or out by the alternator.

DUB

Buccaneer

Yes, single wire. If I remember right it's a 10 AWG, may be larger though. There is no fusible link in that wire since it goes to the junction block.

icpr4u

Thanks gentlemen
I am still chasing down that grounded power wire. It is the black and red one leading from the starter. When I turn the key to the "run" position I have continuity to ground. Almost zero resistance. When I remove the "gauge " fuse the olms increase but there is still some continuity...this I don't quite understand. This seems to be tied, at least somewhat to the Ignition circuit. I am also getting continuity to the powered connections to the fuse block (the rear defog, ignition , etc)

Just as a reminder the battery is out of the vehicle. I have also removed the center counsel.

Anybody know how to remove the fuse block and the connections from inside the engine bay? I'd like to try to isolate the circuits and wiring harness sections..... Unless someone has a better idea on how to do it. I have the two screws out but cannot seem to remove the fuse block

(I am also going to make another post questioning how to remove the fuse block so I can find the issue.)

I had the batt. and ALT checked today at autozone and according to them they both check out.
The hood louver solenoid seems to check out

htown81vette

I had this problem on my 82 CFI. Drove me nuts. I had my alternator tested at autozone too, and it tested 'OK'. But I went ahead and replaced it anyway on a hunch. Problem was solved. I was reading about 12 volts too, but apparently that's not enough for the CFI. New alt read like 14 volts, runs great.

Buccaneer

The fuse box connector is accessed via engine compartment by two screws/bolts (could have been four also) if I remember correctly. Just pull the connector off and when you put it back together ensure you use dielectric grease on the connector.

Again, this was another connector I took off when my engine was out to check for any corrosion, but that was 7-8 years ago.

You might want to pull the connector on the fan high side relay, just to check it. You may be surprised to see that the connector is melted on the backside of connector closest to firewall. I was shocked when I pulled mine and saw that. No indication of issues either...WOW! I replaced the connector that I found at Pomona CA swap meet. Brand new connector cost me $1, I should have bought the entire box of them. They were listed as 65 Pontiac AC connectors. Not sure about that, but it was the exact same connector as the 82 relay connector.

Also the lower leg of starter harness can get pretty bad, make sure you check it out. I believe its the large purple wire, (could be pink also) its been so long since I've been in there, you can't miss which one it is though. If it gets hot, it will melt things in the harness. I ended up making a complete new harness.

Bigredwing

OP - what ever you do be sure to:
- Take Pictures
- Label Wires
- Make your own drawings
- Note polarities
- Write down any part numbers you find on connectors
- Don't force anything.
I am getting worried you are getting "off track" and might accidentally create more issues. As a word of encouragement - take your time. Believe me I know...
-Chris

icpr4u

I removed the connections to the fuse panel from inside of the engine compartment. No more continuity to ground from that power wire! I am guessing the short is in the dash, or the fuse panel is grounding to the firewall
The previous owner installed a Radio/cd changer so maybe the fault is in there.
Who listens to CD's anyway???
Looks like I have some dash removal to do. I have some vac lines to get in there anyway.

Bigredwing-Thank you for your sage advice. I have started a notebook which I'm sure will come in very handy. I appreciate you looking out for me.

lionelhutz

Of course you do. It just means you connected loads to the circuit. If you actually had a short you would either blow a fuse or burn a fusible link.

icpr4u

so the multi meter is just reading continuity on the circuit that is closed when the key is in the start position?

billschroeder5842

icpr4u

just following where the problem leads me...I think

I am following your advice and will put everything back together and start over from step one

My plan is to put the fuse panel back together after testing a few things.

Should there be continuity to ground from the red wire off the back of the alternator with the key in the off position?
I had around 9 olms

Bigredwing

Wish I lived closer and could see what you are doing because I am getting a bit lost. I'll go back to the beginning of the thread when I get some time and try and trace out what you see and refer back to the Service Manual.

Do/did you have any other issues or blown fuses before the idle problems started? If you have not removed the center instrument cluster and everything works I would not touch it. The flexible circuit board can be brittle and the next thing you know other issues can come up and you will be replacing it before you want to. Perhaps you could pull fuses and run your continuity checks to see if anything changes in your meter readings. That might isolate it to a component.