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Electric window issues (Warning: Very strange)

Hello Everyone:

So I finally started working on the basketcase, and have been tackling the small stuff first to gain momentum. One of the things that I started with to be able to drive the car and start troubleshooting it, is to be able to roll down the windows. I took off the door cards and found a bunch of bridged connections and 2 relays. I thought, well, someone put an alarm on this car, and something here is toast. I went on to rewire everything back to stock, and lo and behold, the windows worked! I proceeded to add grease to the rails, and as I was moving them up and down, they died on me. Now, here's the odd part: I have 12v at the switches, the switches work, and the window regulators work, but not together. Allow me to explain. After testing every component separately, I started testing in groups. I got the windows to work from the switches with an independent power input directly from the battery, but not from the 12v it gets from its wiring. It's almost as if the power from the harness just reads with the volt meter and plays a prank on me when I move the switches.

Anybody has had THIS issue?
Old 09-11-2017, 03:10 PM
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I had the same thing. You can read 12 Volt at the switch but it has no power (its a gosht reading). I did the same thing, use 12 volt from a battery charger.

I wish I would remember exactly how I fix it but I'm pretty sure I took all the wires of the switch and restart wiring from scratch.

In order to save weight I later switch to manual crank

Which year is the car?
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Old 09-11-2017, 03:50 PM
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First off, is it one window or both sides?

If you disconnect the appropriate wires from the switch on the door motor side and then with jumpers wire them to a known good battery, you can see how the motor works with the car wiring out of the loop. That tells you if it is upstream or downstream of the switch. If one the motor side, you may have a motor issue.

I have seen bad connections (if you found hacked wiring in the door already) cause this...not enough wire contact to pass the needed current. I had this issue with wires that sat at the bottom of my door for some 25+ years. There were butt splices from earlier issues in the past and those had corroded so much that the motor couldn't get enough juice.

I have also seen wires near the door hinge get worked over the years as the door opens and closes which can cause intermittent connections. You can isolate that from the circular connectors in the fenders. Buzz between the switch and the circular when moving the door or bypass at the the circular connector with jumpers to the switch.
Old 09-11-2017, 06:05 PM
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The car is a 1977, and as I can see, they all share the same power source. The power actually goes into the passenger switch first, and then onto the driver switch. I'm guessing there is probably a contact, connector or pin somewhere that's corroded. The strange part is, it was working just fine until it didn't. Never seen anything like this before. I mean, if I had a corroded contact, I'd have a lower voltage reading, but I get full juice at the wites comming to the switches. I'm hoping someone had the same issue and found the $9,999.00 screw.
Old 09-11-2017, 07:00 PM
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Quote:
Originally Posted by scary driving View Post
... The power actually goes into the passenger switch first, and then onto the driver switch...
From memory, I don't think so but I could wrong. I'll check the manual in the morning.
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Old 09-11-2017, 07:17 PM
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If it is both sides affected, then you are troubleshooting from the battery to the first switch. If it is a one window only issue, then you are troubleshooting from the first switch to that motor.

The power goes to the driver's side switch for the passenger window first...then to the other switches according to my Haynes.
Old 09-11-2017, 07:31 PM
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The power on my '84 definitely goes from the driver's side to the passenger side.
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Old 09-11-2017, 08:29 PM
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M/y 1977

Now that I see that the issue is related to the M/Y 1977,
I deleted my post.

The M/Y '77 P/W wiring is totally different from our M/Y 1986.

Gerry
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Old 09-11-2017, 08:46 PM
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Quote:
Originally Posted by JJ 911SC View Post
I had the same thing. You can read 12 Volt at the switch but it has no power (its a gosht reading). I did the same thing, use 12 volt from a battery charger.

I wish I would remember exactly how I fix it but I'm pretty sure I took all the wires of the switch and restart wiring from scratch.

In order to save weight I later switch to manual crank

Which year is the car?
this is the problem with using a MM to do electrical work. a MM can measure 12v and there not be enough current or power there to operate the load.
use a test light. the light bulb requires current to light. always test the light on a good power source first so you have an idea of how bright it should be.
you can also connect the light to 12v and look for a ground or short.
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Old 09-12-2017, 03:45 AM
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Current draw.

Quote:
Originally Posted by T77911S View Post
this is the problem with using a MM to do electrical work. a MM can measure 12v and there not be enough current or power there to operate the load.
use a test light. the light bulb requires current to light. always test the light on a good power source first so you have an idea of how bright it should be.
you can also connect the light to 12v and look for a ground or short.
^^^^^
Spot on!

Gerry
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Old 09-12-2017, 06:17 AM
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Well, the next logical thing to do is to test at the moment I hit the switch. I'm guessing it's the same thing that happens when your battery posts are loose and you hit the ignition and you just kill the whole car. There's gotta be a contact somewhere that is just not right. So other than the fuses, any hints or clues? Any connections I should be looking for?
Old 09-12-2017, 06:19 AM
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Quote:
Originally Posted by T77911S View Post
this is the problem with using a MM to do electrical work. a MM can measure 12v and there not be enough current or power there to operate the load.
use a test light. the light bulb requires current to light. always test the light on a good power source first so you have an idea of how bright it should be.
you can also connect the light to 12v and look for a ground or short.
Agree 100%. Voltage presence with zero load and ability to maintain voltage under load are two different things. Assuming your battery is good, I would start checking for loose or corroded connections all the way from the battery to the load. Also, check the unusual; such as the power window fuse not fitting in snugly. A loose fitting fuse can create issues under load.

As strange as it sounds, if the fuse shows good but is very old, I would consider just changing the fuse as well. I've seen some strange things when solder joints get old. I recall having a fuse with a hairline crack that only went open when it heated up and expanded. It's a cheap thing to try.
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Old 09-12-2017, 06:33 AM
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On some of our cars there is also relay behind the clock that works with the power windows. Sorry I don't remember what years- but I had a similar problem, found out about and replaced the relay, and weirdness was resolved.

Charles
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Old 09-12-2017, 07:30 AM
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^^^^^
Correct, however, I'm not sure the M/Y 1977 had this relay.

The above pic is for our M/Y 1986.

Best,

Gerry
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Old 09-12-2017, 07:43 AM
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I just tested voltage at the switch and hit it. The second I hit the switch, it dropped to ZERO. It doesn't drop, it dies. Guess this is going to be fun then. I'm going to have to start at the fuses and head down from there to look for the voltage drop. It's clearly a loose or dirty contact.
Old 09-12-2017, 08:54 AM
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Power at the fuses doesn't drop. I'm looking at a connector somewhere. Anybody know where the wires run through?
Old 09-12-2017, 01:13 PM
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circular white connectors in frunk near where the door and fender meet.
Old 09-12-2017, 01:40 PM
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I'm going to go test from there. In a few days. After the bear goes back home.

Old 09-12-2017, 08:33 PM
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this one needed to be fixed

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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ [__] RUNNING: [__] NOT RUNNING:
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[] RUNNING:[_] NOT RUNNING:__2000 MER E320 WAGON [_] WRECKED:[]RUNNING:
Old 09-13-2017, 05:25 AM
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I see the vacuum out there, did he at least vacuum the 911?
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ [__] RUNNING: [__] NOT RUNNING:
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[] RUNNING:[_] NOT RUNNING:__2000 MER E320 WAGON [_] WRECKED:[]RUNNING:
Old 09-13-2017, 05:26 AM
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