Halloween gremlin in headlights
#1
Drifting
Thread Starter
Halloween gremlin in headlights
Haven't posted in a while...
In the 12 or so years I've owned my '92, I've always been inclined to drive with parking lights on. Lately when I shut the parking lights off there is a noise that sounds like the headlight motors operating to close the headlights, even though they haven't been on and so are not open. The headlights currently work normally, and if I turn them on and then off there is no noise.
I think the prime suspect would be the switch or the headlight control module, since there should be no power to the motors when the headlights are not activated. I suspect an internal cross connection-type short in the switch, but I haven't yet done any testing, as I'm still cruising the wiring diagrams in the FSM.
Seems like a good time to put this to the forum, what with Halloween coming and all. Any CFers ever have this issue?
In the 12 or so years I've owned my '92, I've always been inclined to drive with parking lights on. Lately when I shut the parking lights off there is a noise that sounds like the headlight motors operating to close the headlights, even though they haven't been on and so are not open. The headlights currently work normally, and if I turn them on and then off there is no noise.
I think the prime suspect would be the switch or the headlight control module, since there should be no power to the motors when the headlights are not activated. I suspect an internal cross connection-type short in the switch, but I haven't yet done any testing, as I'm still cruising the wiring diagrams in the FSM.
Seems like a good time to put this to the forum, what with Halloween coming and all. Any CFers ever have this issue?
Last edited by sailorsteve; 10-26-2015 at 05:16 PM.
#2
Safety Car
I had this happen to my car once the delrin gear bushings were failing. I cannot explain the connection between the parking lights and the headlights. But I had the same symptoms under the same condition. I was just turning on the parking lights to check the mileage and it happened to me. What I stumbled across was play in the headlight assembly. I just set out to replace the slip bearings on the headlights. After taking the motor covers off I saw the remains of the bushings. After replacing them the units work great and the motors stop spinning at random.
#4
#5
Drifting
Thread Starter
Thanks to all who responded. In my case, the diagnosis I have reached is a failed headlight control module. The FSM describes how the system should work and, using the wiring diagram and test lights, I believe I have eliminated the switch as the problem, and zeroed in on the module. The module is always supplied with battery+ voltage, but isn't supposed to drive the doors without input from the switch.
The headlight switch is double pole, one side for the headlights and one for everything else. In theory, this should isolate the headlight switch signal from the rest of the lights, but I'm not going to hurt myself trying to figure out how the module gets a backfeed signal, in the wrong direction, no less.
Both motors were acting to close the h/l doors when they were already closed. I could hear the worm gears trying to move the driven gears, which I expect are now shavings. The fact that both motors began acting up at the same time also points to the module.
A replacement module is en route, and I'll post back with the outcome. I have also ordered new gears, which I'll install if and when needed. Given the car's age, they could have been somewhat worn previously.
Just another excuse for some "quality" time in the garage playing with my toys.
The headlight switch is double pole, one side for the headlights and one for everything else. In theory, this should isolate the headlight switch signal from the rest of the lights, but I'm not going to hurt myself trying to figure out how the module gets a backfeed signal, in the wrong direction, no less.
Both motors were acting to close the h/l doors when they were already closed. I could hear the worm gears trying to move the driven gears, which I expect are now shavings. The fact that both motors began acting up at the same time also points to the module.
A replacement module is en route, and I'll post back with the outcome. I have also ordered new gears, which I'll install if and when needed. Given the car's age, they could have been somewhat worn previously.
Just another excuse for some "quality" time in the garage playing with my toys.
Last edited by sailorsteve; 10-30-2015 at 09:01 AM.
#6
hope you got the pucks too do not use metal gears.
#7
Drifting
My 95 made the same sounds and I replaced the little round pellet things, they were ground into dust....problem solved. Taking the headlights apart was a bit of a challenge but the parts were less than $8 bucks and the gears were fine. Don't use metal gears!
Your diagnosis may be right but I had the same symptoms with the motor running when I just turned on the parking lights. I really doubt it is the control module.
Rick
Your diagnosis may be right but I had the same symptoms with the motor running when I just turned on the parking lights. I really doubt it is the control module.
Rick
Last edited by Whiteonrice; 10-30-2015 at 11:35 PM.
#8
Drifting
Thread Starter
The fat lady has sung...
I put this issue to bed last week- here is the post mortem. Yes, the plastic pellets were pulverized, as others have found. But I see this as a result, not the original problem. The reasoning goes as follows:
According to the FSM "circuit operation" and wiring diagram (see attached), the module should recognize when the headlight doors are at full open or full closed since the motors then would stop due to physical resistance as the doors hit the appropriate limit stops (adjustable rubber bumpers on the doors). When full travel is reached, the module should break the motor circuits by disabling the grounds. The grinding noises, of course, mean the driven gears are continuing to turn. Apparently, the pellets are the weak link in the system, possibly due to age, so they crumble. When the module is not reading the doors as having reached full travel, the motors keep running, eventually after multiple headlight cycles crushing the pellets into granola. Therefore, by replacing the pellets and/or gears, the underlying problem isn't cured and the new pellets will eventually be pulverized also.
The evidence for this conclusion is the fact that both sides failed catastrophically at the same time, and further that the grinding noises that arose were in response to parking light, not headlight operation, when the doors do not come into play. Conclusion: the module has a headache.
I have replaced the module as well as the gears and pellets and believe this is the ultimate cure for the problem. And yes, I agree that in a system like this, the brass replacement gears are not the best choice- I used the plastic ones.
According to the FSM "circuit operation" and wiring diagram (see attached), the module should recognize when the headlight doors are at full open or full closed since the motors then would stop due to physical resistance as the doors hit the appropriate limit stops (adjustable rubber bumpers on the doors). When full travel is reached, the module should break the motor circuits by disabling the grounds. The grinding noises, of course, mean the driven gears are continuing to turn. Apparently, the pellets are the weak link in the system, possibly due to age, so they crumble. When the module is not reading the doors as having reached full travel, the motors keep running, eventually after multiple headlight cycles crushing the pellets into granola. Therefore, by replacing the pellets and/or gears, the underlying problem isn't cured and the new pellets will eventually be pulverized also.
The evidence for this conclusion is the fact that both sides failed catastrophically at the same time, and further that the grinding noises that arose were in response to parking light, not headlight operation, when the doors do not come into play. Conclusion: the module has a headache.
I have replaced the module as well as the gears and pellets and believe this is the ultimate cure for the problem. And yes, I agree that in a system like this, the brass replacement gears are not the best choice- I used the plastic ones.
#9
#10
Racer
Member Since: Aug 2015
Location: douglasville georgia
Posts: 329
Likes: 0
Received 23 Likes
on
19 Posts
You should have replaced the module only then turn on the parking lights to see if the module was indeed the problem.
My 94 C4 made the motor operating noise when I turned on the parking lights as well and my pucks were bad. I often wondered how it is that the headlight motor would run when I turned on the parking lights only.
A lot of people on this forum that have or had the same symptoms are now left wondering if they have a bad module that will cause the pucks to go bad again.
My car only has 102K on it and the pucks have been replaced at least twice. When I replaced mine a few months back I could tell someone had been in there before because they destroyed the gasket for the cover that goes over the gear. I find it strange that they have gone bad more than once in 102K miles.
My 94 C4 made the motor operating noise when I turned on the parking lights as well and my pucks were bad. I often wondered how it is that the headlight motor would run when I turned on the parking lights only.
A lot of people on this forum that have or had the same symptoms are now left wondering if they have a bad module that will cause the pucks to go bad again.
My car only has 102K on it and the pucks have been replaced at least twice. When I replaced mine a few months back I could tell someone had been in there before because they destroyed the gasket for the cover that goes over the gear. I find it strange that they have gone bad more than once in 102K miles.
#11
Pro
Member Since: Aug 2015
Location: Jackson Wisconsin
Posts: 656
Likes: 0
Received 79 Likes
on
70 Posts
Good explanation. Good job. You 'da man !. I like the body colored wheels. I'm giving thought do doing likewise on my yellow (Big 'Bird) 95. I wonder if I can photo shop it is to see how it will look.
#12
Drifting
Thread Starter
You should have replaced the module only then turn on the parking lights to see if the module was indeed the problem. This would not prove anything, because with the pucks disintegrated, there would be no resistance to the motors, so the module would not stop them.
My 94 C4 made the motor operating noise when I turned on the parking lights as well and my pucks were bad. I often wondered how it is that the headlight motor would run when I turned on the parking lights only.This was a clue to the true problem. The doors are not involved in the parking lights.
A lot of people on this forum that have or had the same symptoms are now left wondering if they have a bad module that will cause the pucks to go bad again.My guess is, they will, without a new module.
My car only has 102K on it and the pucks have been replaced at least twice. This tells you that the pucks were the victims, not the perpetrators.When I replaced mine a few months back I could tell someone had been in there before because they destroyed the gasket for the cover that goes over the gear. I find it strange that they have gone bad more than once in 102K miles.
My 94 C4 made the motor operating noise when I turned on the parking lights as well and my pucks were bad. I often wondered how it is that the headlight motor would run when I turned on the parking lights only.This was a clue to the true problem. The doors are not involved in the parking lights.
A lot of people on this forum that have or had the same symptoms are now left wondering if they have a bad module that will cause the pucks to go bad again.My guess is, they will, without a new module.
My car only has 102K on it and the pucks have been replaced at least twice. This tells you that the pucks were the victims, not the perpetrators.When I replaced mine a few months back I could tell someone had been in there before because they destroyed the gasket for the cover that goes over the gear. I find it strange that they have gone bad more than once in 102K miles.
Last edited by sailorsteve; 11-07-2015 at 12:37 PM.
#13
Drifting
Thread Starter
Back in the day I had a white '92 Grand Prix and the spoked wheels came from GM in body color, which was all the rage then. To my eye it looked like a circus wagon and the brake dust didn't improve their appearance. So the gray was the answer, and the car looked a bunch better.
That car had the DOHC V6 in it- pretty decent scoot for what it was. Today you get better oomph from a golf cart.
#14
Drifting
Excellent info. And I love your floor lift!
How much for the replacement controller?
I want to divide the cost of new delrin bushings into the cost of a controller and see which makes more sense. Two failures in 102K miles could be acceptable at the right price.
How much for the replacement controller?
I want to divide the cost of new delrin bushings into the cost of a controller and see which makes more sense. Two failures in 102K miles could be acceptable at the right price.
#15
Drifting
Thread Starter
Others have bought pellets only for $8-9 per side.
Your motor assemblies may be getting a little frazzled after multiple disassemblies, if it were my car I'd go the whole nine yards and never look back. Could be that the rest of the internal parts are either unavailable or as used only and might not survive serial surgeries to renew the pellets.
As an alternative, use a zipper when reassembling.
#16
Safety Car
The evidence for this conclusion is the fact that both sides failed catastrophically at the same time, and further that the grinding noises that arose were in response to parking light, not headlight operation, when the doors do not come into play. Conclusion: the module has a headache.
Did you have the noise happening at one motor? My headlights had some slack (one far worse than the other), caused by worn plastic flange bearings. This took a toll on my bushings (107k miles, little headlight use) eventually doing one in. I rebuilt the headlight making the noise. As soon as I installed and tested my headlight... the noise moved on to my passenger light. This would be more in line with a conclusion of the headlights completing the circuit and a correctly operating module. Do your headlights have slack in the flange bearing connections? Headlights failing one at a time isn't due to electronics. It is due to play in the system which effects the electronics. I had to rebuild both units with flange bearings and delrin bushings. They are new again and complete the schematic you posted. Thank you for posting it.
Yes, the delrin bushings can be purchased at any auto parts store for around $8. They are Ford window motor bushings. Look for the section with the generic "HELP!" labeled parts.
#17
Racer
#18
Drifting
Thread Starter
You'll need a bit more work to rule out a module having a headache. I am just posting so others don't run out and replace $100 modules. I am happy you having a working car again, this is just for the sake of the subject.
Did you have the noise happening at one motor? My headlights had some slack (one far worse than the other), caused by worn plastic flange bearings. This took a toll on my bushings (107k miles, little headlight use) eventually doing one in. I rebuilt the headlight making the noise. As soon as I installed and tested my headlight... the noise moved on to my passenger light. This would be more in line with a conclusion of the headlights completing the circuit and a correctly operating module. Do your headlights have slack in the flange bearing connections? Headlights failing one at a time isn't due to electronics. It is due to play in the system which effects the electronics. I had to rebuild both units with flange bearings and delrin bushings. They are new again and complete the schematic you posted. Thank you for posting it.
Yes, the delrin bushings can be purchased at any auto parts store for around $8. They are Ford window motor bushings. Look for the section with the generic "HELP!" labeled parts.
Did you have the noise happening at one motor? My headlights had some slack (one far worse than the other), caused by worn plastic flange bearings. This took a toll on my bushings (107k miles, little headlight use) eventually doing one in. I rebuilt the headlight making the noise. As soon as I installed and tested my headlight... the noise moved on to my passenger light. This would be more in line with a conclusion of the headlights completing the circuit and a correctly operating module. Do your headlights have slack in the flange bearing connections? Headlights failing one at a time isn't due to electronics. It is due to play in the system which effects the electronics. I had to rebuild both units with flange bearings and delrin bushings. They are new again and complete the schematic you posted. Thank you for posting it.
Yes, the delrin bushings can be purchased at any auto parts store for around $8. They are Ford window motor bushings. Look for the section with the generic "HELP!" labeled parts.
Rest assured that I beat this diagnosis to death, as I'm not fond of throwing money around any more than the next guy. Bottom line, it's a default diagnosis, meaning if everything else is ruled out, the module has failed. The module itself cannot be tested or examined.
From your description, your headlight problem differed from the others in this thread, with one side failing before the other. Naturally, you wouldn't suspect the module in that case. Glad to hear you solved it. As for the other headlight problems cited here, from the details offered, no one had a similar issue to yours. And, what exactly do you make of those cases where the pellets were replaced multiple times?
Your suggestion that "a bit more work" was needed intrigues me. Please reread my post and then tell me- just what more would you have done in this case?
#19
Safety Car
As in "a bit more work" before coming to your conclusion for the group. It would have been easy to test the original module with the rebuilt headlights. Rule it out for certainty.
#20
Drifting
Thread Starter
If you read my previous attachment on circuit operation, you know that the module, which has B+ voltage at all times, is supposed to sense when the motors have stopped (when limits of travel are reached) and at that point, break the motor circuits.
But suppose the module does not break the circuit until some seconds or minutes after that point- power will still be applied to the motors, which will still try to turn the worm gears and rotate the main gears. The doors can't move any further, so you have the case of the irresistible force meeting the immovable object. The worms have considerable mechanical advantage over the main gears, which, through the pellets, are trying in vain to move the doors. Apparently, the weak link in the system is the pellets, which after an unknown, but not too large a number of cycles as described above, are reduced to granola.
This is why new pellets make the grinding noise disappear- until they too become pulverized. This is why some here have posted about multiple replacements of the pellets. They haven't solved the underlying problem.
It's also why reinstalling the old module will prove nothing- with new pellets, the old module will seem to be behaving until completing the number of cycles sufficient to destroy the new pellets.
On my car, the old module would run for about 10 seconds trying to close the doors when they had never been opened, because I was using only the parking lights, my normal practice in daylight. A healthy module would play no part in parking light operation. Further evidence was that both sides failed at the same time. I would park the car and turn off the parking lights, and the grinding noise would begin. Once I realized what was making the noise, I tested the headlights, and sure enough, same noise.
This is what I meant by "default diagnosis." Solving a problem such as this can be done only with an understanding of how the system should work, along with careful consideration of any and all known info. Testing the switch is basic Wiring 101. Testing the circuit, same deal. After reading the experiences of others in this thread, I'm actually more confident of my conclusion.
Although I have a lifetime of experience at this stuff, on cars, trucks, heavy equipment, and small powered equipment also, I would never claim to be the de-facto voice of authority; that would be egotistical as well as unhelpful. That's why I originally posted here, since a couple of times in the past, I've received very valuable insight from other CF members. All of us are smarter than any one of us.
I didn't do this detailed a write-up before now, as it goes on and on and on... but now I think I've dotted all the i's and crossed the t's.
A couple of footnotes- the FSM is adamant about not plugging in the module unless the battery is connected and the headlight switch is off. This is mentioned on every page of the section. Maybe it's possible to fry the module without those precautions.
At the beginning of the thread, I mentioned that I hadn't posted on CF for some time. Back when I was doing some refurbishing work on my car, I was more active here, getting and giving helpful hints. I'll renew my offer from several years ago to anyone here- I have the complete '92 FSM and would be happy to post or PM any page or pages from it. It has saved my bacon many times.