1999 Regal power window problem

08-31-2013, 05:30 PM
Just replaced the rear window regulator/motor assemblies on both doors. The cable guided regulator just worn out. Now the passenger side rear window will not lower at either the drivers rocker switch or the rear rocker switch. I did check for voltage at the motor connection (two wire) and have 12.4V when raise is depressed, but 0V when lower is selected. Don't want to throw more money at it for new switches just yet, so any help in diagnosing what might be at fault would be greatly appreciated. Thanks in advance.

Blue Bowtie
09-01-2013, 04:03 AM
If it is reasonably accessible, remove the master switch and test the voltages there. Since the lockout switch and source are all there, it's the easiest place to test it all. You may also want to unplug the rear switch and test continuity in both positions.

09-01-2013, 10:03 AM
Ok. Checked continuity between rear window rocker switches and main switches at driver window. The passenger rear harness has a large gauge green wire and appears to the same at the main switch harness. The driver rear harness has a similar green wire of smaller gauge. I get continuity from the drivers rear to main switch, but no continuity from the passenger rear. I'm assuming that this could be part of the problem, in that the passenger rear window will not lower. Hope I'm getting closer with this discovery! Now I need to trace where this large gauge green wire goes. Where can I find a wiring diagram for a 1999 Buick Regal LSE? My search so-far has not turned up anything useful. Thanks.

Tech II
09-01-2013, 04:08 PM
This is for a 2000, should be the same.....


Here is how you test:

Disconnect the harness to the rr switch...attach a test light to "A"(light green) and "E"(purple) harness connectors...now at master switch, with ignition in "on" position, press the rr switch at the master, up.....should light......now press the rr switch at the master, down....should light....

If it lights going up, but doesn't going down, OR lights going down, but doesn't going up, you need a master switch....

If it lights in both directions, and your motor is new, and the wires to the motor are ok, you need a new rr passenger switch....

If it doesn't light in either direction, then you need to check the continuity of the light green and purple wires.....if ok, need master switch...

09-01-2013, 06:55 PM
Thanks, Tech II.
Ironically, I had found the same wiring diagram, purely by accident. With no continuity on '3 LT GRN' wire between the master switch @ pin E and RR switch @ pin A, I am inclined to rig up a jumper from pin to pin. Once continuity is established, I will test the function based on your instructions. Thanks again.

Tech II
09-02-2013, 11:16 AM
What I would do, is open the front driver's door, and disengage the rubber loom wiring cover between the door and the "A" pillar......look for that light green wire there....give it a tug, you will probably find it broken from the years of flexing caused by opening and closing the door......

09-11-2013, 07:14 PM
Finally able to get back to troubleshooting the RR power window. As before, the Lt green wire did not have continuity from master switch to RR switch. Started tracing the wire through the door jam and found it cut clean in two at the in-line connector! A simple butt splice took care of the continuity issue. However the window still would not lower. Started messing with the plug at the RR switch. This is where I made most of the voltage and continuity checks. With the switch connected, holding the raise or lower down and wiggling the plug, the regulator motor came to life...in both directions. Too dark to do anything else tonight, so tomorrow will try to make the connector sockets a little tighter. Getting very close!! :)

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