I just bought an 85 corvette and dont know much about them but i wanted a fun project to learn with. One of my biggest problems are the headlight motors. When i got it the driver side motor would go up and down but when opening the headlights the motor doesn’t turn off. the passenger side motor was just completely shot. i bought a rebuilt passenger side motor but the guy must have messed something up during rebuilding because when i turn the headlights on the motor wants to close the headlights and vice versa. i was wondering how i can fix this myself without having to deal with the seller on ebay? Thanks!

 

Try this: disconnect the arm to the motor. Then turn the manual **** until it stops. Reconnect the arm and try it! Had to do that on my firebird.

 

what do you mean by the arm? do you mean the housing or the screw that connects the motor to the light housing?

 

It might be an issue with the headlight control module. I have an '88, and it's a small box mounted on the driver's side front wheel well, facing towards the front. I know some fieros and firebirds of that era had the same unit (although without the threads for mounting screws), so if there's more of those in a nearby junkyard than corvettes that gives you more options for troubleshooting. Prices seem all over the place on ebay.

 

The metal arm /linkage that connects to the motor shaft that raises and lowers the light.

 

just checked the relays, they’re both good. i’m at a loss because all the wiring seems good and i plugged the old broken motor into the wiring to see if it would move and it also went in the wrong direction. i have ground at the green wire and power at the gray when it’s trying to close which checks out with the diagrams ive seen, makes no sense

 

This is a known issue with C4's. There are tons of threads on the forum about headlight repair. I think there's even a sticky. I gutted mine and did a total re-wire to finally eliminate all of these issues. But you have a decision to make. Are you going to try and repair 26 year old wiring or re-wire it. Either way you NEED a shop book. Don't even bother without one. Get one off ebay or download a digital copy.

I know i'm in the minority on this but I decided to eliminate the isolation and ripple current relays in my 84 all together. I pulled out all of the old chopped up factory wiring for the headlights, fog and front marker lights. I then set them on fire and rejoiced. Then I put in all new wiring with a new relay box. I added a toggle switch to control light up and down. This eliminates 99% of the issues with the lights not going up and down properly because you are eliminating the old controls. Here are some pictures on what I did.





Sorry the pictures are upside down. The relay box is just a universal one from ebay. I have the relays labeled. L is for low beam H for high beam U is for motor up and D is for motor down. The brown one is for the fog lights.



Sorry the car was so dirty in this pic. It was still in storage. Anyway this is the toggle switch I put in for the headlight motors. Making it so you control them in the same way as power windows instead of off of the old relays. This eliminates so many problems.

This is how I did it so it guaranties that I won't have issues unless a motor fails. Again either way you NEED a shop manual to fix this. Otherwise your just throwing money at it and hoping.

 

not sure i want to redo all the wiring cause the left one works fine, but you’re definitely right about throwing money at the problem lol. today i bought new relays and replaced them but it made no difference. i have a shop manual but it doesn’t really say anything about the headlights except for a wiring diagram which i’ve been looking at, i’m not the best at reading those though. where i’m at right now is a new motor and relays and the wiring being presumably good from the testing i’ve done but it’s still going backwards??

 

I can't remember the details, but the instructions say when installing your new motor, crank the light closed manually before powering it up. When you installed your motor, which way was the light when you first turned the lights on, open or closed?? Post #2 may be your answer.

 

i don’t think its that because when i just plug in the motor without the housing or anything it still is going the wrong direction. it’s going counterclockwise to close when it should be going clockwise.

 

Are these 2 or 3 wire headlight motors?

 

3 wire

 

Sorry I did not explain better. I had the exact same problem as you are having on my 2001 firebird after I put a new gear in the driver side and could not get the light to go up and down with the pass side light. Finally I unhooked the up/down linkage, then turned the the lights on so the pass side was in the up position. Then I disconnected the battery and then manually turned the driver side **** until it stopped (just turn it which ever direction it will go until it stops). Then hook the linkage back up and reconnect the battery. Hope it does the trick. I spent hours and hours before I accidentally did this procedure. Almost bought a brand new motor thinking I screwed up the one I just rebulit!

 

If I remember correctly (I could be wrong) the 3 wire headlight motors use one ground wire and a forward (UP) winding and a reverse (Down) winding. I would unplug the headlight motor that is running in reverse. Using a multimeter verify first of all that you have a good ground connection. Then using a jumper from the positive terminal on the battery find out what pin on the light motor harness makes the light go up and what pin makes it go down. Then reverse the two wires (UP and Down). I don't know how they could have been reversed. The headlights in my 84 were wired horribly wrong by the previous owner so anything is possible. But switching the polarity will make it go the other way.

 

It's not as simple as that, there is not a single common or shared wire as one would imagine, instead it operates as two 2 wire motors with a shared lead that is connected/disconnected by the internal limit switch. So in normal operation the 2 "up" have a positive let's call it green, and a negative let's call it white, when the headlight reaches the end of its actuation the green is disconnected from 12V by the limit switch, but the relay is never de-energized so any any loss of torque on the motor will untrigger the limit and allow the light to move to the greatest height it can achieve. When the light switch is pushed in, the isolation relay flips the polarity of the middle wire, which we'll call the white wire, is now positive and the brown wire is negative. The light will run until the limit on the other end is triggered, the negative disconnected and the whole thing comes to a rest. It's a complicated system but replaced the need for current based limit sensing electronics, with a torque sensitive electromechanical solution. There should be three relays total for this system, an isolation relay, driver side light relay and pass side light relay. Getting the motor put back together is very tricky, I had to refer to the pictures multiple times in order to get it right, if he had it apart, it is safe to assume that the 2 direction wires are backwards, but first verify that the relies operate as they should other wise you'll short the motor, melt the wires, and then you're pulling the headlight apart to solder in new wires, trust me it's a pain you do not want to experience.

 

I admit wiring is not my strong suit, and I have not done a lot with headlights (just enough to be dangerous ). But it seems to me the motor runs one way, then it runs the other. If the linkage is put on with the light in the wrong position, it's going to move the wrong way. See Wilcar's post a couple above this one. Sounds like that's exactly what he had.

I may be all wrong but for a relatively simple procedure, do as suggested, reverse the position of the light then re-connect the linkage. I'd sure try that before re-wiring things. If that IS the problem, you'll be home free.