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Seth Rose

another headlight thread? OH MY!

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Im having trouble with my drivers side headlight door.  It doesnt work at all the light its self works on high beams and on low beams.  It has new bell cranks and has new rollers as well. (thanks Barney) I want to make sure im getting power to the motor does anyone have any idea how to do this?  I hooked a multimeter to the two wires that plug into the motor and nothing when I flipped the lights on.  Perhaps I hooked the multimeter up incorrectly?  I have a spare control module as well just in case (thanks Jim) this really has me stumped the passenger side works just fine with both switches.

Thanks guys. 

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Try hooking up the passenger's side motor to the driver's side connector and see if it works and vice versa. The connector itself may also be the problem if the wires aren't fully seated or it got water inside it.  I find with these things it's best to just work your way back through the system until you find the problem.  Bear in mind that this is a GM product and you'll get all sorts of problems if you have less than perfect grounds.  So check those too.

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Most likely the headlight actuator relay module which is located on the driver wheel well under the fuse box. I have one listed on eBay if you need one.

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Ok I hooked it to the passenger side motor and it still didn't work.  so I followed the wires back through the loom and pulled them out to make sure they were not broken. followed them all the way back to the control module.  Its a new used one from Jim Finn so it should be fine I have no reason to doubt the control module.  any ideas? is it possible it could be one of the pins in either of the plugs.  Wiring looks pretty straight forward.  2 wires to each motor.  also that green plug sitting on the other wiring loom.  where does it plug into because it was unplugged when I started this task was just laying there. looks like a ground but it doesn't run into the loom for the lights just curious.

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That single terminal green plug is a 12vdc input to power the fuel pump. It is not normally connected to anything, and is used mostly for diagnostic purposes or if you need to pump out the fuel tank it can be hooked to 12v and it will run the fuel pump continuously as long as power is applied. I just recently used this to pump the gas out of a parts car (through a hose attached to the schraeder fitting on the fuel rail) I bought before dropping the tank so it didn't weigh as much. Much easier than than trying to syphon it as well.

 

KDirk

 

 

 

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Ahh good to know!  Ok back to the headlight question.  Would a burnt out high beam cause the headlight not to pop up??  I'm at a loss here the motor works plugged it into the passenger side and it ran. 

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I would still suspect the headlamp control module, despite having replaced. Internally, it has two control circuits, one for left and one for right. It is possible (have had it happen on one of my cars) for one side to fail and the other operate normally. Other than that, only the wiring is possibly an issue near as I can see. The low beam filaments need to be intact for proper functioning, but I do not believe an open high beam is likely to be the cause of any problem.

 

KDirk

 

 

 

 

 

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As KDirk mentioned, the low beam filaments, which are wired in parallel, are used as the grounding pathway for the headlight door module electronics.  It takes BOTH low beam filaments to be burned out to impact the module and in that case, operation of BOTH headlight doors is impacted.  Since you have proven that the driver's side motor is functional, that leaves only the wiring and the headlight door module as suspect.  You need to use an ohm meter to verify the wiring between the module and the door motors as corrosion can sever a wire internally with NO outward signs (this happened to me on one of the ground wires near the battery).  Since you have two headlight modules (the original and the replacement from Jim) doing the same thing, I would really focus on the wiring.

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You originally said both the low and high beam lights worked, so the last few q and a should not apply.

You said you traced the wires for the control box to the motor connector,  did you use a meter on them?

There is also a chance a wire is shorted (rubbing against some metal surface) and moving things around might have solved that problem

 

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Correct Barney but it was after I had just put a new bulb in that the highs worked.  It has to be in the wiring some where as the plug to the module isn't get power to the right pins.  I used the service manual to trouble shoot that.  I don't have the time right now to chase the wiring all the way back as I'm leaving in 2 weeks for Air Force BMT so I'll just raise the light manually for now thanks guys for all the help. 

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Does the light close electrically after being raised manually? Does the replacement module have the correct part number? I don't have an early manual but I think I remember the early and late models use a different module, although I would think neither light would work if that was the case.

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FWIW, All four years of Reatta use the same headlamp control module. The Fiero used an identical  (or ay least compatible) module though I'm not certain of the compatibility with Corvette modules. There is more than one part number, due likely to running changes that GM was always making during production.

 

KDirk

 

 

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