Hello,
For my '68 I'm looking to do a set of electric RS headlight doors. I recently purchased a set of headlight motors and control module from a '96 TA. After a little research, I've found the wiring diagram. I've done the research and read everything I can on the 3rd gen swap. I've also seen reference to the thought that you don't have to do switch modification or use a set of relays if you were to find a 4th gen headlight control module. When mocking it up on the bench I've run into some issues. Regardless of the "headlight" switch position (open/closed) any time I apply power to the control module, the headlight motors seem to run without stopping. Is this normal? Are they supposed to continue to turn until they sense enough resistance? I have tried to apply resistance to the motor by holding the shaft, although the motor never stopped. I felt I was at risk of stripping the gear if I was to apply any more force.

The following link is a wiring diagram for the 4th Gen headlight assembly.
http://s5.photobucket.com/albums/y169/RhinoSS/misc/?action=view&current=98TAHLMPMOD.jpg

Here is how I currently have it wired:
A.) Switched 12+ (Emulating headlight switch) This is a normally open push button switch. It completes the circuit when held down.
B.) Constant 12+
C.) Nothing connected
D.) Ground
E.) Constant 12+

A.) L Headlight Motor lead 1
B.) L Headlight Motor lead 2
C.) R Headlight Motor lead 1
D.) R Headlight Motor lead 2

If anybody could provide insight to why this is occurring please let me know. I appreciate any help you can provide.

Something else I may add... The lights and control module were said to function properly when removed from the car.

I've found this page that has a little more insight on the swap: http://www.mcspeed.homestead.com/Our_Products.html
I'm having a hard time completely trusting what they're saying given the diagram I posted previously, although they seem to be very knowledgeable on the subject. I'm simply worried about frying my control module and want to be 100% certain before I make any changes to how I have it wired.

If using the 93-02 Firebird module (Part # 16525685) the wiring is a bit different. The up signal is wired exactly the same and can be done using the stock C3 headlight switch. The down signal is accomplished by simply grounding terminal "C" on the Firebird control module. This will cause the lights to drop as soon as they are turned off, even if the parking lights remain on.

This is stating that I should ground C when I want the headlights down, although looking at the diagram it appears to be a 12V+ feed coming from the tail lights fuse :confused:

I re-tried a '94 module on my '89 motors tonight and grounding "C" did the trick! and yes the wiring diagram shows C as a power connection. go figure?

The module cuts power only after the motor stalls, so try holding the shaft a little tighter ( I clamped a cresent wrench on the shaft and it jammed on the housing to cause it to stop.

It is also good to see that a 84-89 Corvette headlight switch should work with the earlier module, and that the newer module will work with the earlier motors.


TTFN
Mat

Thanks for your help Mat. I'm really glad to see that is working for you.
I've tried this setup again today, wired up exactly as I have it in my original post. As soon as it's powered on the headlight motor begins to spin. I held the motor to the point of stall for about 2 seconds and it still wanted to run.
In your testing, how long do you have to hold the motor before the control module shuts it off?

Another question this brings up. Did you do your testing inside or out of the car? I'm simply trying to use a 12V source outside the car and wire the headlight module as a stand alone system. I have no other electrical load on the system. Is this something that could only be mocked up inside the car?

My test was outside the car. Just a couple of jumper wires to a battery, with terminals B&E twisted together.
I had a cresent wrench on the stem. The motor went until the wrench jammed on the motor housing. FWIW The service manual says 6 seconds.

TTFN
Mat

This is really starting to confuse me. Maybe I somehow managed to screw up my control module? At any time did you have 12V+ hooked up to terminal C? I wired it that way due to the diagram I found previously. I also errantly had the headlight motors wired backwards at one point. I don't think it would make a difference, although I guess you never know. Currently they are correct to the diagram I found.

I couldn't get the motor to stop after holding it for approximately 8 seconds with my 12V power supply. Thinking a battery may provide better amperage, or slightly more voltage, I tried it jumpered off a car battery. I ended up with the same results.

I've tried it with both nothing and a ground wire hooked up to terminal C. Regardless of the headlight switch position or how I'm using terminal C I can not get the motor to try to stop turning. Maybe I should try holding it for 30 seconds or so to see if it ever stops. I'm sure I have to be missing something, I'm just unsure of what that is right now.

Don't sweat it Ryan I do not think you burned the module. I'm sure I had C connected to power at some point and the motor polarity does not matter, you will likely have to change it to synchronize the system anyway.
Continue with mounting the motors ETC. then try it in the car. once it is together and if it doesn't work I can send you my module to try.

TTFN
Mat

if you really get stuck, see if you can email him: http://shbox.com/1/4th_gen_tech1.html or read up on his site.

He's a 4th gen electrical guru and can probably help you out good. You may also want to post on www.cz28.com where he usually hangs out.

-Jason

Jason,
Thanks for the additional link. I'll have to do a little bit more research over there as well.

Matt,
Thanks for offering your known good module to test. Unfortunately I'm quite a ways away from actually being able to mount the headlight doors to test so it will be a while before I'm able to test in the car. Just to make 100% sure I understand the wiring in your test, can you take a look at this crude MSpaint rendition of my wiring?

http://i5.photobucket.com/albums/y169/RhinoSS/misc/wiring.jpg

That looks like the wiring I tried (only the picture is a lot neater:)). Try it in the car you should be O.K. and send picture of how the motor mounting worked out, I would like to see.


TTFN
Mat

Well, if it's like you've tested, I'll just roll with it :thumbsup:
Thanks for the input. I'll let you know how it turns out.