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Power Window Fuse Blowing
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=91294		 Page 1 of 1
Author:  iakj11 [ Sun May 03, 2020 12:50 pm ]
Post subject:  Power Window Fuse Blowing
So out of nowhere the other day my power windows stopped working. Fuse #13 (40 amp) was blown under the hood. I replaced it and found that it blows instantly upon turning the key to run or acc. I've removed both front and rear switches and tested them per the procedure in the FSM. The main switch wasn't right continuity wise, so assuming that was the problem, I acquired a couple replacements and several fuses from the local salvage yard. Before installing a new switch, I tried another fuse. Fuse still pops with both switches removed. This is leading me to believe there is a short in the wiring somewhere between the main power window switch harness and the relay in the junction block. A little digital multimeter checking at the power window master switch harness with the negative battery cable disconnected found no resistance at pins 10 and 13. 13 is ground and 10 is the fused ignition switch input. Nothing in the harness or the junction block looks obviously burned or melted. I removed the relay to inspect, but did not remove the junction block.

1) Am I correct in assuming that there is a dead short in the power window fused ignition switch input wire (PK/YL) that is causing my problem?
2) Anybody know how that wire is routed? I don't have a short finder tool.
3) The front windows are stuck open right now. Can I temporarily apply 12 volts directly to the right pins in the harness to get them to close or will it burn something up?
4) What have I missed or what else should I check?

Thanks!
Author:  WWDiesel [ Sun May 03, 2020 4:08 pm ]
Post subject:  Re: Power Window Fuse Blowing
Tests you can try:
1. With Ign. switch in the "OFF" position, plug power window relay back in.
----Unplug power window master switch and lay aside. Install good fuse in #13, turn Ign. switch to "ON" position and see if it pops fuse.
2. If it pops fuse in test 1 above, you have a short in harness between power window relay in fuse panel and the connector for the power window master switch.
Note:----ign. switch enigerizes (closes) power window relay when Ign. switch is place in the "ON" or "ACC" positions. This puts 12v (power) to terminal 87 which also puts 12v to terminal #10 at power window master switch connector.

NEXT:
3. Remove (unplug) power window relay in junction block (fuse panel in dash)
-----With good fuse in #13, turn Ign. switch to the "ON" position and see if it pops fuse. It should not.
----With the relay out, and the Ign. switch in the "OFF" position, measure the voltage with your volt meter at terminal 30 where the relay plugs into the panel, it should be 12v powered all the time straight from the battery.
----Next, with the power window master switch unplugged from the wiring harness (disconnected) using your ohm meter connected to a good body/chassis ground on one lead and the other lead connected to terminal #87 where relay plugs in, check for continuity, you should NOT get a reading. If you do get a reading between #87 to ground, it tells you have a shorted wire to ground between the power window relay on the fuse panel and the power window master switch connector. You will need to trace wire (pink/yellow no. 14 ga. wire) to find where it is touching a ground source.
4. If you don't blow a fuse with the power window relay installed and the power window master switch unplugged with the Ign. switch placed in the "ON" position, the power window master switch is bad. There is a diode in that switch that can go bad and allow 12v to go straight to ground according to the FSM. \
:POPCORN:
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Author:  iakj11 [ Sun May 03, 2020 10:39 pm ]
Post subject:  Re: Power Window Fuse Blowing
Thanks for the additional tests WW. Did those this afternoon, and I'm now sure it's a short between the master window switch and the power window relay. I guess I have some fun to look forward to, that wire looks like it is buried under the console, and who knows where it ends up under the dash.

I did manage to get the windows closed with the FSM pinout table, a jumper wire and a paper clip.
Author:  WWDiesel [ Mon May 04, 2020 12:30 am ]
Post subject:  Re: Power Window Fuse Blowing
iakj11 wrote:
Thanks for the additional tests WW. Did those this afternoon, and I'm now sure it's a short between the master window switch and the power window relay. I guess I have some fun to look forward to, that wire looks like it is buried under the console, and who knows where it ends up under the dash.
I did manage to get the windows closed with the FSM pinout table, a jumper wire and a paper clip.

If you don't want to really trace the OEM wire all the way through the console and through all the wiring harnesses in the dash, you could simply run a new wire from the relay plugin (#87) to the connector (#10) for the master PW switch and abandon/cut the OEM wire. :idea:
May be much easier and quicker fix???? :juggle:
Author:  iakj11 [ Mon May 04, 2020 5:57 pm ]
Post subject:  Re: Power Window Fuse Blowing
WWDiesel wrote:
If you don't want to really trace the OEM wire all the way through the console and through all the wiring harnesses in the dash, you could simply run a new wire from the relay plugin (#87) to the connector (#10) for the master PW switch and abandon/cut the OEM wire. :idea:
May be much easier and quicker fix???? :juggle:


Is it possible to access the actual wiring behind the relay in the junction block to do this? Or are you saying just wedge a new wire in plugin 87 on the relay side of the junction block and cut/cap the old wire as best as possible?
Author:  WWDiesel [ Mon May 04, 2020 10:37 pm ]
Post subject:  Re: Power Window Fuse Blowing
iakj11 wrote:
Is it possible to access the actual wiring behind the relay in the junction block to do this? Or are you saying just wedge a new wire in plugin 87 on the relay side of the junction block and cut/cap the old wire as best as possible?

Never done it, but I would try and locate the offending wire behind the fuse panel and cut it and connect a new wire using proper crimp connectors and do the same of the other end at the master switch. If you drop the fuel panel, be sure and disconnect the battery while working on it.
I certainly don't recommend jury rigging a wire stuffed into the relay plug. Not the correct or safe way to fix things...
Author:  iakj11 [ Tue May 05, 2020 10:40 am ]
Post subject:  Re: Power Window Fuse Blowing
Has anyone removed and/or split open the junction block to access the wiring behind the relays? Not sure I dare try it.

Otherwise I can probably identify the correct wire in one of the bundles under the steering column. Problem I can see right away is that there is more than one pink/yellow wire....
Author:  WWDiesel [ Tue May 05, 2020 11:58 am ]
Post subject:  Re: Power Window Fuse Blowing
iakj11 wrote:
Has anyone removed and/or split open the junction block to access the wiring behind the relays? Not sure I dare try it.
Otherwise I can probably identify the correct wire in one of the bundles under the steering column. Problem I can see right away is that there is more than one pink/yellow wire....

Harbor Freight has a cheap wire tracer (tone generator) for $25 bucks
https://www.harborfreight.com/cable-tracker-94181.html
Could use it to locate the correct wire in the harness.
Author:  iakj11 [ Fri Jun 12, 2020 9:54 am ]
Post subject:  Re: Power Window Fuse Blowing
I'm still messing with this. Bought a cheap wire tracer, but have learned that if I have a short to ground (which I believe i do have), it just makes the tone carry through the whole chassis. Anyway, before I cut any wires, I want to inspect the wire harness in the junction block. Anybody know how to get this thing apart? In the pic below the one I need to open up is the black one in the upper left of the photo. I can get the bolt in the center backed all the way out until it just spins and then the harness will unplug, but I can't seem to fully separate it from the block to inspect the pins. Are there some clips I'm not seeing? A super secret technique I'm missing? Thanks!

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Author:  WWDiesel [ Fri Jun 12, 2020 1:04 pm ]
Post subject:  Re: Power Window Fuse Blowing
Get yourself one of these, a simple cheap short finder. I have one, a similar SnapOn version and it works quite well for finding a dead short to ground.
Google "Automotive Short Finder", there are plenty of them available on line. :google:

It connects in place of the fuse that is blowing and pulses current on the circuit and you move the induction meter along the wiring harness and when the indicator needle in the induction meter starts bouncing in the opposite direction or quits bounding completely, you have found your short to ground.
Have used mine many, many times to locate a dead short to ground and it works. :D

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Author:  iakj11 [ Fri Jun 26, 2020 8:16 pm ]
Post subject:  Re: Power Window Fuse Blowing
Finally got this fixed. I was able to separate the harness (C2 in the FSM) by pushing the plastic clip on the left side of the harness to the side after backing out the retaining bolt. This allowed me to use a multimeter to verify that my short was not in the junction block itself between the harness and the relay. It also allowed me to visually inspect the harness. Anyway, running a new wire from the C2 harness to the power window master switch fixed it. Drive thrus and various other curbside interactions are much less awkward now!
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