GKK

I've been trouble shooting an intermittent headlight problem for a couple of weeks now and I'm still at square one.

The Symptoms:

1) Sometimes only the driver side headlight rotates up and down other times they both don't rotate and sometimes they both work fine.

2) Both headlights always light whether the headlight units rotate or not.


What I've done so, far:

1) Checked for 12volts at the Headlight Control Module and at both the green and grey headlight motor wires (all had 12 volts).

2) Replaced Headlight Control Module = no change.

3) Checked battery voltage (all OK).

4) Changed the headlight motor bushings about a year ago.

5) I unplugged four relays two on the driver side of the radiator and two mounted on the rear of the driver side wheel well but, none of these control the headlight motors because both headlights still worked with the relays unplugged..


I returned from vacation and went into the garage to check the lights and both worked fine. Today I checked them again and they were still fine. I drove the Vette to do an errand and when I arrived back home, Both headlights would not rotate up.

Would a fusible link cause this intermittent operation? I've searched and searched but, similar posts are just about bushing replacements and motor replacements. I really appreciate your help. Thank you

Hooked on Vettes

There's two fusible links at the battery jumper block which is located behind and below the battery and used by the headlight control module.

If you look at the drain tube for the driverside cowl, it dumps water right onto the battery jumper block which can cause corrosion on the fusible link terminals.

I added a piece of radiator hose to extend the drain so the water is dumped below the fenderwell area.

Disconnect the negative battery terminal. Remove the side gill panel then the nut holding the fusible links to the stud. Clean the terminal lugs.

mseven

when they go up, is there any continued sound from motors?

GKK

There is no sound at all. Either one headlights works or both headlights work or don't work.

Thanks, Hooked on Vettes for the picture. I redirected the drain tube awhile ago but, I'm still going to check the fusible link connection tonight. It seems like the problem is so simple!

mseven

well it was a shot....I know mine did some weird opening and closings (intermintent) but still worked. Couldn't figure it out, then one day they still opened but motor continued to run for a few sec. Tore it down and bushings were powder on one side.

GKK

Well, I just checked all the fusible links and they were all fine. I also, sanded the terminal and fusible link ends while I was at it.

Both headlights still wouldn't rotate but, I heard a click as I turned the headlight switch to on.

I then turned both headlight ***** about one turn each and they both worked as usual. I find it hard to believe that both headlight motors would go out at the same time.

GKK

Does my "91" Vette use any external Headlight Relays? If so, can anyone tell me where they are located? It's the last thing I have to check before installing the new headlight motor. Thank you so, much.

Tommy T-Bone

Was the headlight control module new or used? Could it be defective?

mseven

no relays that I could find, 91 should be the same as mine, this may help:
you're going to have to crank screen size up to read I left sizing down for 650 didn't have time to re-shoot

Hooked on Vettes

Since you manually turned the motors and they both started to work points to bad bushings. I think you can pull the side gear cover off the driverside motor and examine the bushings without removing the headlight bucket.

When you rebuilt the motors last time, did you use the Home Depot bushings?
Some people have reported those bushings failed after a short period of time.
I think the bushing dimensions were not exactly the same as what's being sold by the Corvette vendors.

You should beable to manually turn the headlight **** to open and close the headlight bucket with no slippage or binding.

GKK

Thanks for the diagram mseven, it was very generous of you to scan your FSM. a lot of members are protective of there manuals and just say, you need to buy a FSM. Referring to the chart, Looks like I did the correct procedure.

Hooked on Vettes, I bought the bushings and plastic gears from Mid America and there is no slipping or binding when manually opening the headlight doors.

Also, The headlight Control Module was new but, It wasn't the problem because the same symptoms occurred with the new unit so, now I have a backup Control Module.

Update:
Last night I decided to install the rebuilt Right side headlight motor I bought from Eckler's and after an easy straight forward install, (about an hour) the lights work fine. I'll most likely have to buy the drivers side motor as well since it acts up once in awhile.

Thanks, everyone for all your help!

Hooked on Vettes

Yiou should try repairing the motor.

Seperate the motor housing from the gear box. Watch for the two springs that pop out used for the brushes.

Clean the commutator of any carbon brush residue.
If the brushes are worn out, get some from an auto electrical repair shop or Napa, Auto Zone etc... that are close in size. (alternator brushes). You can sand the brushes down to the correct size. Solder the braided copper lead from the new brushes to the old leads.

To hold the brushes in place, I used dental floss. Looped it around the braided copper brush lead, pulled back on the dental floss and installed the armature and housing back into the gear box.

For a couple hours of work, you could save yourself $175.00.

GKK

That's a good idea Hooked on Vettes. If the drivers side headlight motor acts up again I'll check it out before buying another $129 rebuilt unit from Ecklers.

mseven

you're welcome and no problem. I have seen the same often, to me if it's something I know or have access to I don't consider it a breech of national security. looks like you have it under controll.

Hooked on Vettes gave you some great info,...as I re-call when I first came on this board he hung in there to help me resolve my power antenna issues and it helped me fix the problem, still owe him for that and thanks.

GKK

Update:

Well, I installed the passenger side rebuilt headlight motor and everything worked fine. Then, while testing the headlights the Driver side headlight motor stopped working.

I ordered a rebuilt driver side headlight motor from Eckler's and installed it. Everything worked great. While I was cleaning up and putting away my tools, I decided to check the headlights again and found the driver side headlight stopped working again.

I frantically checked for 12 volts at the headlight motor (which it had) and tried to calm down and figure out what happened. Then, after a short prayer I thought it could be the new Headlight Control Module that I recently bought from Mid America.

I quickly unplugged the new Headlight Control Module and installed back the original Headlight Control Module. Bingo! Both headlights worked great! I decided to open up the new Headlight Control Module from Mid America and found that it had an electrical smell. I looked closer and saw a little white wire that had a small electrical burn on it.

I just spent $169 for this new headlight control module and it lasted only two weeks!

Well, the headlights have been working great now and I'm relieved that this is finally over. Thank you, everyone for all of your help!