Power Window Motor questions - Help! - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

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post #1 of 4 (permalink) Old Jun 4th, 01, 08:36 PM Thread Starter
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Join Date: Apr 2000
Location: CA SF Bay Area
Posts: 94


This is the situation: On my '79 Z28 neither of the power windows worked when I got it. I found the switch (in the console) was bad, jumping it made the passenger side work. But not the driver side, just sparks.

So I did these tests: I pulled the driver side regulator/motor assy. Before plopping down the big buck$ for a new motor, I tried it out of the car, in case maybe it was just stuck linkage or something. It worked OK, fast in the direction the spring was helping, slow in the other. The motor windings checked at about 1 ohm. I used a battery charger to power it, and put a voltmeter on too. The battery charger pegs out at 10+ amps, while the voltage drops to around 7-8 volts, at the motor. So I wondered, what does the other motor, the one that works, do? I made the same check, and found the same result. It goes down fast, up slow, and draws 10+ amps at 7-8 volts, that is at the switch.

Here are my questions: Are either or both motors bad? Is that why the switch went bad? Is it common for these power window motors to draw way too much current, but still work? How much current should they draw? I checked the fuse box for a clue, it seems the "power accessories" are run by a 30 amp circuit breaker, not a fuse!

If the motors are bad, it seems like taking a chance on junk yard replacements would be a bad idea, same for the switch. I see the motors at Year One for $120 each, Classic Industries at $140 - $160 depending on which side (?!?), and Paddock at only $70 (well, maybe my catalog is a bit old, but that is a BIG difference). Is the quality the same? The switch seems to be in the $60 - $80 range. Could I get the motor rebuilt somewhere for less than a new one? Any other ideas for reasonable cost sources?

And my last question (for now) is, the connector to the switch is shot, melted around the terminals. Iwould like to replace it (as a pigtail). Bit I can't find it! Any ideas? Or should I just cut it off and solder the wires to the switch (yuk).

All responses are deeply appreciated! Thanks!

now: '73 LT; '79 Z28
then: '67 coupe; '88 IROC; '95 Z28

[This message has been edited by ibjoe (edited 06-05-2001).]
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post #2 of 4 (permalink) Old Jun 5th, 01, 07:05 AM
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Join Date: Jun 2000
Location: LaGrange,Il
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You can probably find a connector at a junk yard and cut and solder the wires. Because it is melted there probably is a problem. It doesn't sound like a motor problem. Is the wiring good and not shorted? or intermittantly shorted where it goes thru the door. or rubbing on the regulator asm? I suspect the drivers side. I've had wires break there before.

I personally have no problem with junkyard motors, the last ones I bought were $12.00. For that kind of money I wouldn't mind changing it again, If need be.

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post #3 of 4 (permalink) Old Jun 6th, 01, 03:47 PM
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Join Date: Mar 2000
Location: ohio
Posts: 1,014

I need to replace the window motor in my daily driver Caprice. I tested the entire circuit and determined the motor was the problem. Local Chevy dealer wanted something like $150 for the motor. Advance Auto carried new and reman both with lifetime warranty, reman was only $40-$45, can't remember exactly. It doesn't look like a fun job to replace so I haven't tackled it yet. Just thought I'd pass this along.

Bret Copsey
'68 Camaro base coupe
'92 Caprice wagon
'98 Malibu
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post #4 of 4 (permalink) Old Jun 7th, 01, 03:46 AM Thread Starter
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Location: CA SF Bay Area
Posts: 94

Well I got it working now! I think the original problem was a combination of binding linkage and bad connections. I took the motor and regulator out. Once out of the car it seemed to work OK. So I cleaned up and re-greased the linkage and put it back in. Both sides draw about the same amount of power, they both go up and down and about the same speed. Those motors DO draw a lot of current, esp if the battery voltage is low.

The connector to the switch was fried, but I took it apart and cleaned up the melted plastic. I can make the windows work now by jumping the leads (pink to any other).

The switch is bad too. I will take it apart and see if I can fix it. Because new switches are $60 -$80, as far as I can tell. I guess I'd try a junkyard switch before a new one.

That switch switches around 10 Amps, I think. I didn't have a meter to tell exactly, but that's about how big the sparks are. The "power accessory breaker" in the fuse box is rated at 40 Amps.

No wonder the switch goes bad! Probably there should be a relay the switch operates instead of switching the current directly.

What I learned was: 1) don't assume the motor is bad because it doesn't work, it could just be stuck and 2) with circuits that draw a lot of current (like power window motors) good connections are crucial! measure the voltage right at the terminal of the motor, it should be about the same as the battery voltage when the motor is running. Well, maybe 1/2 or 1 Volts less, due to the resistance of the wires. Also, make sure the gound is good! There should be 0 volts on the motor ground, when checked to a good chassis ground (or battery -) when the motor is running.

Thanks for the comments!

btw, the other link about this project is https://www.camaros.net/forum/Forum3/HTML/001422.html

now: '73 LT; '79 Z28
then: '67 coupe; '88 IROC; '95 Z28
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