Please Help: Left side power window is dead

[tecqboy]

My driver's side power window has stopped working in the full up positioin. It worked yesterday and today it doesn't. It doesn't move when activating the top / deploy switch either, so the problem is unlikely the console switch. It has "parked" about 1/4 inch higher than normal, so I suspect something like a limit switch. Does anyone know if there is a limit switch in the window mechanism? Can anyone point me toward an electrical diagram of this circuit? BTW, the right side is OK. Tod

[tecqboy]

Update for anybody following the story. I found that with the engine off and the radio off, it was quiet enough in the car to hear a relay clicking when pressing the window switch. The relay sound is coming from under the right side rear storage compartment. The top deployment controller is in there I believe. So, that means the switch is good and the primany fuse is OK too. Next step, remove the door panel and search for limit switch on the regulator drive motor. Door panel removed, no power going to connector for the motor. Zero ohms to ground both wires. Bad sign. Had to leave for work. Tomorrow.....Tod

[tabo]

I fixed several MLS with faulty window switches.. most likely the window switches are made from the same manufacturer .. check out the switch ok?

[tecqboy]

The switch in the console is OK. The switch "fires" the relay in the control box. Power to control box is OK too as right side window is working. But no power at door motor. Will tackle the control box Saturday. Also, will try to run motor directly with 12V supply. If the motor is shorted to ground, then perhaps there is a blown fuse in the control box, but this seems unlikely at the leads read about zero ohms to each other and ground. SInce only 2 leads go to the motor, either a limit switch or a current limit sensor and polarity reverse relay are required. This is complex; that's why I wish I had a diagram. Thanks for your input. Tod

[LOWMILE]

I forgot where i read... or who told me... but my 1972 350SL does not have a limit switch. What year is your car? My five year old loves window switches and I would hope to figure out what I need to do to limit her use of said switch. I have taken apart and cleaned both switches and the spring inside now works better. Switch moves rocker action back to neutural "off" position much quicker than before.

[bobterry99]

Outputs for the window are pins 1 and 2 from the soft top controller's Z-connector. The schematic does not show that a limit switch exists in the regulator mechanism (but maybe it is implied). There is a limit switch in the bottom of the door that closes when the window is completely lowered. However, I think it is only used by the controller for automatic operation.

Found this in a Technical Service Bulletin: the window motor has a hall sensor, though it is not shown on the schematic.

[tecqboy]

Final chapter: for anyone following this story. I disconnnected the window motor from the controller box and jumpered it to a 12 Volt power supply with an amp meter. The motor ran, but was very slow going up; drawing more than 10 amps. Reversing the leads and running it down, it drew about 7 amps and ran slow and erratically. I then figured I had a bad motor, so I proceded by peeling off the water damn paper covering the door frame to get to it. Well, I guess I really shouldn't have been too surprised at what I found. You see, last year a bolt broke off inside my convertable top deployment mechanism. Reason? All the grease had dried out on the moving parts. What I found in the door was that all the grease on the moving parts of the regulator had turned into hardened clay. This car spent the first 8 years of it's life in southern California where the temperature is often over 120 degrees F. Now I don't know if that is the reason all the grease on this vehicle has turned into mud. But, removing the hardened grease from the window regulator and re-lubricating it with new white lithium grease has it working smoothly again. Not an electrical problem at all, except for the fact that the controller box probably has some current limiting to avoid damage to relays and wiring if the window should stall. And that's a good design. Thanks to all who provided advice. Tod