Blackhawk67

i know there are other questions and fixes for this but they are for the headlight control module. and i cant find anything for the relays.
ok so.

my driver side headlight wont go up but the light turns on. the motor does not make a single noise. i have a relay by each headlight. if i take the relay from the pass side to the driver side still does not work. but if i put the driver side relay on the pass side the pass side does not work eather. i dont know where to go next...
all in all the passenger side works and driver does not. the lights go on both but the driver side does not go up.

Base91

iTrader: (1)

It sounds like one relay is bad and you've also lost power to the driver side relay. The lights and motors are on separate circuits so you may have to wind the light up by hand but at least you've got lights. Check the fuse (or fusible link) for the driver's side. Maybe if the relay went bad it blew the that side.

Blackhawk67

where would the fuseable links be at? i dont know what any of the fuses are under the steering wheel because all the markings are worn off..

i should add that yesterday i took my car out and the headlights both went up but then the driver side would not go down. and now all my left marker lights wont work... any ideas about that? im lost

Base91

iTrader: (1)

Unfortunately tracing electrical problems is one of the most frustrating things to do because the wires disappear into looms and behind panels and there are so many wires and circuit variations. You need a manual with the circuit diagrams, a digital volt meter (dvm) and patience to do the reading and testing. I bought a new module for my lights only to discover (by accident) a broken ground wire nowhere near the headlight module or relays. The majority of electrical/electronic issues are actually mechanical. Corroded terminals, broken wires etc. You'll have to learn to read the circuit diagrams, use the dvm and check wires for continuity (not broken) and check connections everywhere. You need to isolate parts of the system and test each part so you're only dealing with one issue at a time. Also it sounds like one headlight mechanism may be bad. Check the mountings and bushings etc. to make sure it can move freely. Sorry not to be more specific but remote electrical diagnosis is not always simple.

black85vette

This is very similar to the early C4 Vettes. The headlights are controlled by 3 relays. One controls power and the other 2 each control one headlight. Nice thing is that you can swap the left / right relays to troubleshoot the problem and elminiate them as an issue. If either headlight works then the 3rd relay is already eliminated.

Inside the motor assembly of the headlight are two limit switches. A follower on a worm gear pushes against some springs and when the headlight has reached its mechanical limit the switch is opened and power removed from the motor.

Those interior switches are common failure items and a bit of a PITA to deal with. You have to take the motor off and then take it apart to get to them. The common failure mode is that the motor will either open or close but not the the other. This condition also validates the motor / brushes are OK. So it is just a process of elimination to isolate the limit switches as the problem.

It is also possible to have more than one issue like a bad relay plus bad limit switch. I have diagrams of the headlight wiring in block form and some pictures of the inside of the motors if you are interested. I can post a link to my Flickr account.

Blackhawk67

thanks for the input i will check that next once i get the new driver side relay. those diagrams and pictures would be great!

black85vette

Here is a link with some pics and the drawings;

http://www.flickr.com/photos/1757654...57602882678033

Hope that helps