I'm trying to sort out this headlight problem. I did a search and there is certainly a ton of info (maybe too much), so I will ask directly.

I have the two-wire motors that work (I tested them off the battery). My lights light when I throw the switch. If I touch a test light to the terminals that plug into the motor, one pin will light the light, the other does not (I'm assuming this is the ground). I guess I should actually test the voltage though. My questions are these; first, if I have power down to the terminal, can I assume the module is good (is it an all or nothing thing)? If I find the module is OK, is the only possible remaining culprit my headlight switch? Are there fuses or relays that could be causing this? From what I gleaned out of the archives was that my 88 setup did not use relays, just the module. If this is true, there are only the switch, the module, and any fuses to consider. True?

Thanks in advance for the help.

Kevin

 

What are your headlights not doing ?

 

I just went through this on my 91 bird. I tested for voltage to ground at each terminal on the motor plug, both of them had 12VDC. As it turns out this is normal, the module switches the ground from one wire to the other when raising and lowering the lights. After playing around with the lights I found a sequence which I had to go through to get the lights to work properly.
I manually cranked the driver side light up with the lights off, then turned the lights on and back off. The driver side light lowered at that time. Next I cranked the passenger side light up with the lights off, turned the lights on, driver side raised, turned the lights off and both lowered and functioned normally from there on out.
I have done this sequence a few times (removed lights for painting and removing/installing a fender and nose piece) and the lights wouldn't work unless I did the above steps.
This may or may not be how they all have to be done, but it is the only way I can get my lights to work properly.

Another thing you can check for is unhooking the battery while listening to the module, you should hear a click when disconnecting and when reconnecting. This is the relay inside of it energizing and deenergizing. If you don't hear it clicking you can suspect the module is bad.

 

To answer the previous question - the headlights don't raise (or lower when dialled up manually). All lights illuminate however. I tried Morley's strategy (I was sure that would work) to no avail. The motors work when jumped off the battery and I hear the module click when the negative battery cable is disconnected, but the headlight doors do not move. I just changed the headlight switch also and I have power down to the connections. This is driving me crazy - what else could it be?

Kevin

 

When you tested for power on the harness plug at the light, did you take note as to how long it was getting power ?

Thiere is a slim chance that the gearing/lift points need a good lubing and are creating enough resistance to cause the module to cut power.
The module seems to cut power to the motors by way of resistance (circuit break type shutoff) and/or time (found this out through scientific research).
If there is an excess of resistance to raise the motors, the module will prematurely stop the motors.

The test light or multimeter should show power for a few seconds before cutting off (no load to the module).

With the motors plugged in, backprobe the harness plug to see if there is brief power to the wiring. This would sort of verify the resistance theory.

Just a kind of 'out in left field' thought...

 

Good thought, except the motors don't work even when they are not connected to the headlight assembly (they do when jumped from the battery however).

I did notice (when I changed the swich on the dash) that one of the female connectors within the strip of female connectors (that comes from behind the dash) was missing. The headlight switch has 7 or eight "teeth" that plug into a white connector with 8 female connection to accept the teeth. The second (or third, I'm not with the car so I can't remember) from the top, female connector is empty. Is this supposed to be like that or did it possibly pop out of the harness and fall behind the dash? If anybody can take a look a theirs or knows offhand, I'd appreciate it. If need be, I can take digital photo of it and send it to anyone who has a car apart.

This is the ONLY mechanical thing left to do to this car before I send it for body and paint work. I probably just totally jinxed myself, didn't I?

Kevin

 

Yep, it's very possible that they do need a good cleaning. If I remember right, the only thing that stops the motors is when they slam open, the motor resistance raises and triggers the module to stop. There isn't any switch or anything that tells the motors to stop.

 

But the motors don't turn even when when they are not connected to the assembly. Does that not matter? There should be very little resistance just to turn the shaft (without lifting the door), no?

OK, I'll do it anyway- A cleaning couldn't hurt anything anyway. What specifically should be done?

Also, Can anyone answer this...Can the headlight module be bad but the headlights still light anyway?

I'm going to beat this thing. I swear.

Kevin

 

Yes, the headlight control module doesn't control the lights, just the motors to drive them.

 

A HA! Now we're getting somewhere. That was throwing me off because I have one module that doesn't lift the doors - but the lights don't light either. I was assuming this is how a bad module acted (or didn't act).

I bought another module (ebay or a thirdgen classified, I can't remember) and when I hooked it up, the lights lit up but the doors didn't open. So I figured that now I had a good module but bad motors. Now I know the motors are good (from jumping them off the battery) and the lights work, but the doors still don't open. I am guessing that the module is bad because when I followed up with the person that sold me the module (it was a money-back if it didn't work kind-of-thing) and told them it worked, they were surpised - like, "Really? OK, then...nice doing business with you."

I guess I will search out my third module and see if that does it.

Kevin

 

This made me assume that the module is sending power to the motor when you turn the lamps on... or am I wrong ?

If there is power at the plug on the motor (motor disconnected), then the module is doing it's job (so far). The other part to note is how long does power stay on to the motor (with 0 resistance).

The module does indeed cut power by detecting resistance (some form of a circuit breaker). I learned this when I did my headlight mod. If there is an abnormal amout of resistance to lift the lamps (i.e. dried up grease in the motor, door housing binding), the module will stop immediatly instead of trying to force the lamps up.

This also may/may not help but, here's a confusing diagram of the door module... http://www.deadbird.org/tech/head.gif

 

Go to a junk yard for modules, it'll be cheaper.

Try this, disconnect both motors and check each pin of the harness to ground, it should read 12V on both and nothing from pin to pin (Verified this on my car with the headlights functioning properly)

 

If you open up a module and follow the traces on the board you'll be able to take some of the mystery out of that diagram. The only "solid state" there is to the module are a few IC chips mounted on the board (I suspect they do the current sensing and switching of the relay)

 

So if I put a test light to the disconnected plug and throw the headlight switch, the test light should stay on until I turn the switch off (no resistance), correct?

And if I have power down to the connector, then the module is OK, correct?

So that leaves the probability that the motors need to be greased (which is what most of you have been saying). I have resisted this explanation because the motor didn't turn even before I connected it to the assembly. But alas! I now realize I had not disconnected the OTHER motor, so that one may have been stuck and causing the module to shut off. If I disconnect both motors from the assembly and plug them (or one) in, they should turn because there will be significantly less resistance.

I guess the next step is to lube them up and see what happens. I'll do a search on that and see if TDS has any info.

 

I'm sooooo confused.
Are you saying that the headlights won't crank up manually?

when you go to crank them to the up position they will at first look like they are going down (1/8" or so), that is normal, they then should start going up. You can crank them up with or without disconnecting them.
When I checked mine the headlight switch was off and both motors were disconnected. I checked each wire to ground and got 12V, I then checked from wire to wire and got 0V. After that is when I started playing with the position of the headlights and cycling the switch on and off and eventually found the "routine" I mentioned above to make them work. I think it has something to do with syncing the headlight motors to the logic of the control module.

 

Yes, the headlight doors crank manually - up and down.
The doors open and close when jumped by the battery.
The headlights light up when I turn on the switch (but the doors won't open -unless I dial them up myself)
I have power down to the connector.
I have tried your method of trying to cycle the doors to the module several times - nothing.

 

I;m having the same problem. But I'm not getting any juice to the motors. Where is the module located and the relays.

 

Module is on the firewall on the driver side, the only relay is in the module.

 

actually he has an 86 and there are 3 relays one is on the firewall drivers side one is passenger side near rad, the other one one could be anywhere on the drivers side. I have found them on top of the fender well and near the rad.

 

So, he's not talking about the 88 GTA that's in his sig in the original post ??
He's got my name.. I have to believe him first

 

OK, I used a 1991 Firebird service manual to do the headlight door troubleshooting. It looks like I have a bad wire from the headlight switch to the C1 connector (the longer strip of wires that plugs into the control module). I don't uderstand how the wire could be bad or, more importantly, how I'm going to change it. The manual states that this wire (C) along with (A) carry the current that opens the headlight door. They give a whole bunch of tests to do - ie With the switch to "park" touch the test light to this wire & ground - test light should light. Touch it to this - it should not light - a whole series of things like that. All of these tests are done with C1 disconnected from the module (between the headlight switch and the C1)- so I know my module is not the problem.

My car is an 88 but I only have the 91 manual (its probably the same) - if anyone has an 88 manual and can find, copy, scan, and email this section to me - I'd be forever grateful.

Kevin

 

The wire may not be broken, it might just have corrosion on a contact. Did you try a continuity check from one end of the wire to the other?

 

All I can really see of the wire are the ends as it snakes through, over and under all the other looms. The thing that puzzles me is that on one of the tests (in the service manual) with the headlight switch to "park", the C (brown) wire is supposed to light - it doesn't. Then with the headlight switch to OFF, it is not supposed to light - but it does light the testlight. If the wire (connections) were shot, why would there be any current running at all (even though its not supposed to be at that specific point anyway)? Could the problem be with the ground, and the C wire is acting like the ground in that instance?

I was just going to change the connectors at the end of the wire. It got late last night and I didn't have the right connectors. Thanks for hanging in with me. It's going to be a happy day when those lights finally go up and down by themselves.

Kevin

 

Sorry I was talking about Morley having 3.

 

nope, just the module. If you have the module then you only havethe relay that is in it.

 

Deadbird, that was Biggwinn that has the 86, not me. He jumped on board with similar symptons in the middle of the thread.

My 88 was parked (outside) for 6 years. Its taken me more than a year and I've addressed every mechanical issue (the car runs awesome- finally). The biggest pain in the **** has been these darn headlight motors.

I can't find the connectors aftermarket - I guess its either GM or the boneyard.

Kevin

 

I was messing with these damn headlights again tonight. Here's the new development. I changed all connectors and the headlight switch - no improvement. But I found that if I disconnect the module, dial the lights up manually, turn the headlights on, and then reconnect the module, the lights will go down. They will not raise again and they will not lower if the lights are on, dialed up, and I turn the headlight switch off. The only action I get (except for opening manually) is the doors closing when I plug in the headlight control module. I did a search and found (from another post),

"After installing my TPI, my headlights would turn on but not go up, I bounced the car and they went up...hmmm, I was perplexed until I found the ground by the passenger side in front of the Air-intake box on the radiator core support." John

After all this, it's probably just a ground. But if any of this rings a bell for anyone, I'm open to suggestions as I am at wits end with these headlights.

Kevin