I’ve replaced everything I can think of to make these headlights work right on my 1990 coupe. Initially they wouldn’t flip at all, up or down, though the headlights themselves came on and turned off via the switch on the dash. Motors, headlight control module, then the entire headlight asemblies themselves just because I found a matching color of a different set with very low mileage on em.

With the new (brand new) headlight control modue, the lights flip up now, but not down.

I moved on ad did other things that needed to be done on the vehicle but now that I’ve got all of that stuff done I’m back to the headlights problem. And the weekend his here, so I’ll have time to tinker with it some more.

There’s not any headlight relay switches on the ‘90 models, is there? What else could it be? Any ideas? Thanks for input.

 

Idk man.....think the headlight switch might have a dead spot in it?...
You know,...like a light switch, flip it on and it comes on then off. But if you move it just a little to that sweet spot it'll work.....idk just a random guess....

 

 

 

It's a pretty simple system. My guess is since you have replaced everything upfront, it's probably the actual dash switch tossing out bad signals. It sounds like you just tossed parts at it without troubleshooting it. I would be looking at the signal coming from the switch and work forward.

 

Ok, I’ll replace the switch and see what happens. I’ll clean it up first, though and give it a check.

I’d already planned on replacing parts when I bought it anyway, so thats why I swapped stuff out there.

Admittedly, though, I don’t know how to decipher those diagrams. I need to take time to learn how. I know what it is, it’s basically a map, but those abbreviations leave me clueless. I have a service manual, but It’s useless to me in a lot of ways because of that little shortcoming. I looked through the manual when I was wondering why the radiator fan always came on when you turned the key, those diagrams lost me. I forgot about that, actually.

Thanks, all. I’ll report back if it works.

 

Did you do the small bushings in the motors?

did you check all fuses? There is a second panel under the passenger kick panel.

 

True, there is a fuse for both directions.


Some abbreviations to help:
DRL= Day Time running Lamps (You want to use the one that says W/O)
B=Black
Y=Yellow
DG=Dark Green
And so on.

With the switch in the off position, you should have Voltage on the Dark Blue and Dark Green Wires. If you do, issue is in the motor. If not, Check the fuse, then check voltage output from the switch, Then the Headlight Door Module may be bad. If all checks out and changing the module doesn't solve the issue, you probably have a broken wire, loose ground, or a chaffed wire that is shorted.

I

 

Nope. Wasn’t the switch. Not as it relates to the headlights not going down anyway. Though my interior lights are coming on now when I open the driver side door. Before only the passenger door turned the interior lights on when you opened it.

I thought it was the button in the door but I guess not. At least it wasnlt a wasted part, it fixed something anyway. Thanks!

 

Nope. Didn’t mess with the bushings this time around. I replaced those initially but the lights still wouldnlt go down (or up). Then I replaced the control module, motors, headlight asemblies since they had cracks in the glass, headlight switch now and they do go up at least, just not down by themselves. I can close them manually, so I’m asuming the gears are good on the new motors. Rebuilt, thouhg, not new.


As far as fuses, the ones in the passenger side dash are all goood. those are all that I checked.

I noticed the previous owner hotwired the fan, though. The secondary fan isn’t even hooked up. There’s also a fusible link cut at the jump start junction behind the battery. And I don’t know what the previous owner hotwired the primary fan to. each side of the headlight control module I replaced does have its own fusible link for each side of it, it looks like. It could be fusible link K, too, because I asked the previous owner about it and he said the air conditioner stopped working .So, I dunno, I’m going off of memory, I don’t even have the car now, it’s in the shop getting some suspension work done to it, I dropped it off over the weekend.

When I get it back, maybe it’ll be a ittle cooler and I can look at it and trace everything. So far that’s really the only iffy wiring I’ve seen.

Usually people hotwire the fans right at the relay but the previous owner didn’t. It’s spliced somehow inside the conduit.

I almost want to start at the air conditioning wiring and switches and work toward the fans following everything and then put it back to oem and then fix the ac.

 

Thanks for that. I have been trying to read the electrical manual for these particular parts. I think I want to redo the wiring back to the way it’s supposed to be (which I have to learn from the manual still) and then check voltage. When I get the car back. I’m just not an electric guy.

I think the lights not going down has something to do with the fan hotwire, but it’s just a hunch, not an educated guess. Reason being is that the ac still works. It just blows hot air. All the vents work, too. I think he cut one of the headlight fusibe links and then hotwired the fan to it. Either way, I have to figure out what he hotwired the fan to and undo that first before I even attempt to diagnose voltage.