I replaced the heater core and it seems so long ago and now more problems.

I had that same thing happen to me.  I got voltage to the motor and everything. 

It turned out (as best as I can figure out) to be a ground issue.  I got voltage but it would not hold under load because of the increased resistance caused by a bad ground. 

Anyway I cleaned the ground between the motor and the bolt holding it to the door and it has worked fine for over a year now.

Just cause you can measure voltage does not mean that it is there under load.

Just my thoughts on it.


|UPDATED|9/4/2012 12:27:50 AM (AZT)|/UPDATED|

I had the similar thing happen to me yesterday. I got through working on the center console and my passenger side window would not go up or down. I checked for voltage at the switch, which I had. Flip flopped the switches around, no changes. But the driver side window which has the original motor worked slow but worked.

So I figured I'll tackle that problem later. But after letting the car run for awhile to bring the battery back up, I tried the window again and it worked. So I think there might not have been quite enough juice to make the motor operate. Kinda weird because I replaced that passenger side window a few years ago and never had an issue.

These are some of the reasons I became a Mechanical Engineer and not an Electrical Engineer!

I looked at the book and the car do not see the ground from the motor to a bolt, just the two elec wires?

One of the first set of test leads I made was from a 15amp extension cord.  I cut off both ends of a 15 foot cord ant put on clips.  Now I can take 12 volt any where I want.  I was told that the motors are really strong and seldom go bad.  If they do you are better off purchasing a used one than the new ones.

That said I put 12volts directly to the motor and it worked for me.  Now I knew for sure it was something between the motor and the battery.

There is no ground except the motor housing as far as I can remember.  It was the motor not making good connection with the mound that was my issue.

I have a brand new battery but will take the leads directly to the motor and also check the mounting bolts and nuts, figure it's something simple or I pinched a wire in removing the dash, as it had worked fine.  Will try when the next free time comes up.  Thanks again. BB78

Left window at motor

Be careful running hot wires o the window motors....you do NOT want to shoot 12v and a ground to the two terminals on the motor. You only need 12v on ONE of the terminals at a time...one to power it up, and the other terminal powers it down. The motor is grounded to the window frame itself thru the casing, as has been mentioned.
So, basically, putting 12v to one of the terminals on the motor runs the motor in one direction, and 12v on the other terminal runs it in the opposite direction. If you run 12v to one terminal, and ground the other terminal, you may let some of the smoke out....
Try tapping on the motor with a small hammer while shooting voltage to it....you wouldn't believe how many times that gets them running again.

Have had the same issues. Put in a new motor, had power up & down w/test light, but no motion. Like rraider said, the TWO wires that feed both sides, change motor direction only, so window goes up & down. The ground is through the motor housing, to the door frame, to body. Any loss of voltage under load because of a not so good ground, will cause the motor to work slowly or not at all. I also found a faulty power window switch connector. It seems that the red  power feed into these switches get a loose connection sometimes that you can't see. So after wiggling the wires, while activating the switch up & down, the window took off just like new again. If you have this issue, you can buy new connectors & splice them in for cheap money @ most corvette parts suppliers, mamotorworks, ecklers, corvette america, etc.