vetteset8087

I have an 87 glass top coupe it has the updated 89-96 headlight doors that take the actuator module instead of the 2 relays these worked fine for years then the drivers side headlight would not open I powered the d-side headlight with a battery at the connector and it opens and closes fine so I figured it was the module I opened the module up took out the circuit board plugged the incoming connector in normaly then plugged the outgoing connector in backwards turned the lights on and the drivers side opened fine but the passenger side would not work again this tells me it's the module put everything back together as normal opened the drivers side light manually then turned the lights on then off and both headlights close fine this tells me that the wiring from the module to the headlights is fine again the module is bad more specificaly the contact on the relay in the module that opens the d-side door is bad so I buy a used module off ebay put it in and the same thing d-side headlight won't work run all my tests again and conclude this module is bad also I buy one of Corvette Masters new reproduction modules wait a week get it put it in and nothing neither of the headlights work wont open or close they say it is a bad unit they send me another one put it in and the same thing nothing both headlights do nothing they send me another one put it in and again the same thing both headlights do nothing put my original module in one headlight works the other only closes itself when opened manually I have now ordered a factory GM module that will be here on wednesday I am hoping this is the problem can you guys think of any other problem that could cause this or any other tests i should do

jfb

I would need a circuit diagram. I have an 87 with 3 relays and the module would need an up signal and a down signal. I would think the module would use the yellow wire from the headlight switch for up and the grey wire for down. I doubt that all of the replacements are defective the same way, so I would check continuity of the up wires from the output socket of the module to the headlight motor socket. I suspect one or both up wires are open circuit. Measure the resistance from module socket to the motor socket, it should read the same as touching the ohmeter test probes together.

Hooked on Vettes

One of the connectors at the control module should have (2) 14 awg red wires. Both wires should have 12 volts at all times.

Both wires are fusible links and come from the battery jumper block behind/below the battery. It sounds like one of the fusible links is blown or has a bad connection.

vetteset8087

Does anybody have a schematic for the 89-96 headlight and door actuator system or the pin out for the plugs going into the module to tell me what each wire is supposed to do I have the shop manual for the 87 but it does not show anything on these headlights and I don't want to spend $125.00 on a book for a car I don't have. I have a constant power and a headlight switch switched power coming (Both red wires) in to the module the wires from the module to the headlights should be fine they both work one at a time when the outgoing plug is changed from being put in the right way to being put in backwards Rich at corvette masters said that the power is split in the module he said if one headlight works then everything before the module is fine and the module is bad the modules Corvette masters sent sounded like they may have been prototypes first they sounded like they sold thousands of them then they said they had 12 in cars then they said that they had 1,000 of them made and the manufacturer sent them 3 early I had all 3 I think my car was the test platform

Hooked on Vettes

Use a magnifing glass and you should be able to read the schematic.

vetteset8087

do you know the location of the underhood fuse block it shows on the top left of the schematic over the years I have been all through this car and don't remember seeing one. the LH and RH 30 amp fuses are making me think I may have another problem but one headlight works fine and the other will close itself if opened manually so it should mean that I have the main power needed to both actuaters Thank you very much for the schematic Hooked on Vettes my GM dealer gave me one that might just as well been drawn with a crayon it didn't show anything

vetteset8087

Hooked on vettes you are awsum you had it on your first post I ran power from the batt to wire 542 terminal E and both lights work now I will find the fusible link or bad connection tomorrow and fix it this car has been down for three weeks because I didn't want to drive when it wasn't perfect over a dumb supply problem I owe you one

Hooked on Vettes

Sorry, I posted the schematic from a 93-96.
They use a fuse for the two hot wires in the top left of the schematic.

Your setup should use fusible links. Trace the wire and it should go back to the battery jumper block which is located below/behind the battery. You'll see a bunch of red orange colored wires bolted to a stud.

Removing the side gill panel will make it easier to get at the fusible links.

Since your car has been converted to the new style headlight control module and an upgraded wire harness I can't say for sure the above information is 100 percent accurate.

vetteset8087

Behind or below the battery is a challenging place for me to get to my ground effect on that side has to come off then the skirt then my MSD sits on top of the battery so it should be fun but you made it easy at least now I know I am doing it to fix the actual problem not just pokin and hopin I will let you know how it went thanks again Hooked on Vettes

vetteset8087

success both headlights work fine now it was the fusible link I went ahead and replaced both of them. both were on the same conector instead of taking a chance both got replaced. I used 18 gauge fusible link wire from autozone it was a little hard to tell what the right size was so I bought all 3 sizes 18 16 14 gauge and used the smallest first to be safe. the core of the 18 wire looked the closest Thank you again Hooked on Vettes

Hooked on Vettes

You guessed right. The fusible link is 18 AWG for that circuit.