Ok..I have what I think to be a legit question here..

My one headlight, does not go up and down like it should.
I plugged the "dead" motor in on the other side and it works, so that tells me the motor is good, the line is just dead.

So i located the HCM on the firewall and it has 2 plugs comming out of it..

One for the left, one for the right i would guess..

Now if this is true so far, could i theoreticly plug them in the oposite socket, in reverse, and see if the opposite side works and the other side stays down? Then I would know its definitly the module that needs replacing.

Hope you get what im saying, lol

-Joe

PS: its a 89 trans am

 

It's a good theory but, it's not correct.
One side is power & headlight switch 'signals',
the other is to the headlight motors.
This may help your elimination process.

 

Another theory shot to hell. ;(

Is there anyway to check the HCM to see if it is that that is at fault?

 

What I did was pull out the "dead" motor and plug it in to the connector on the "good" side. The motor was alive! So I went to the junkyard and pulled a HCM out of a wreck, installed it, now everything works great!

 

Did that exact same thing, if that means its the HCM, ill go get a new one.

 

Headlight Control Module? Mine still has the indivisual motor relays and isolation relay. When did it change to a single module?

 

87 (or, at least sometime during 87)

 

Yep motors changed over in 87.

I just bought aHCM on ebay , lets hope that is my problem.