'99 Suburban Left Rear Window Stopped Working

[510man]

The left rear window on my '99 Suburban stopped working. It's an old truck so I replaced the window motor. Worked great when done......and then didn't work an hour later. Step 2, I replaced the rear door switch. No change.

This was relatively cheap guessing. Now I'm to the driver's door switch, which is more expensive to replace. Before I do that, how do I trouble shoot correctly?

I have power and ground at the rear door switch. I have continuity through the switch pins when tested with an ohm meter.

Where does the door ground to the body? In the B pillar between the doors? I ask because I could have ground when testing with a volt meter but it may not be good enough to carry a load.

 

[Big Mama]

Did you try swapping a working switch?

 

[510man]

I bought a new left door switch. No change. I don't have an extra driver's door set of switches to try. I'd have to buy it. I'm trying to make sure that is the problem since that switch is a spendy part swap test.

 

[Big Mama]

Sorry, are the switches on the other doors the same? I have an 07 and they are but I can’t recall if yours are? Are you able to test the motor?

 

[510man]

The two rear door switches are the same. The front doors are different. The motor is new and worked fine after I installed it. Came back to the truck an hour later and nothing.

 

[Big Mama]

Right but since it’s not working anymore try the same diagnostics you did at first. My switches are the same on 3 doors so popping one out to test the other is quick and easy.

 

[east302]

Here are the diagnostics for a window inoperative from both the window switch and the master switch. Maybe it will help. This is for a 98.

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[Big Mama]

@NathanJax can someone make this s sticky?

 

[NathanJax]

@NathanJax can someone make this s sticky?

Done

 

[510man]

Thanks for the test info. I'm at Step 1. I used a volt meter vs a test light. I have voltage at the terminals when the switch is operated either way. I ordered a second new motor that arrived today. It's a Delco so we'll see what happens.

 

[510man]

Back to close this one out. The new Delco motor works. The switch was fine. Both the new and old switch work fine.

So what was wrong?

On close inspection, the gear width (not diameter) of the VDO motor is about 30% greater than the OEM motor. As such, when the three motor mounting bolts are tightened down, the gear is forced against the mounting bracket creating a bind where the gear can't turn. The OEM gear flies over the mounting bracket by a few thousandths of an inch. Adding 30% more width isn't going to work. The VDO and Delco motor look identical when you hold them side by side........but upon closer inspection, the gears are different and it's a critical difference.

Problem #2 is that it's easy to bend the mount slightly when drilling out the factory mounting rivets. They tend to spin before you get them drilled out so you have to pry and chisel them out. That said, I bent my mounting bracket ever so slightly but it was critical to the gear clearing the mounting bracket. I used some thin washers on the three motor mounting bolts between the motor and the mounting bracket to shim the gear away from the mount .030" or so. It gave me just the clearance I needed. The gear spins freely and the window now works as it should.

I would have purchased the motor and mechanicals as an assembly but it wasn't available for the rear door. I could buy it for the front doors but not the rear doors.

Hope the info helps the next person.

 

[east302]

Thanks for updating, that’s good information to keep in mind.


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[Big Mama]

Great example of parts aren’t just parts.