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Old 12-28-2013, 09:32 PM   #1
1968k10blue
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electrical issues

So, I went to start my truck today, and I turned my heater fan down to use less power to start the truck, and suddenly the heater, blinkers, wipers and aftermarket tach stopped working. I know it some type of short but I was wondering if anyone has any ideas on where to look first
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Old 12-28-2013, 09:53 PM   #2
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Re: electrical issues

It still runs? Those are the only circuits dead? Wondering if u lost a fuse/fusible link under the hood. ?
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Old 12-29-2013, 01:12 AM   #3
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Re: electrical issues

Yes it still runs, what was listed above are the only things I could find that dont work. I checked the fuses, none looked to be burned out, but I was going by a dim flashlight in the dark so I will look into it further later on, I have a small feeling it has something to do with my heater controls because of how it was acting before this happened. it is hard to explain how it acted but I will start there and let you know
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Old 12-29-2013, 01:32 AM   #4
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Re: electrical issues

Use a test light. Turn key on and touch each side of the fuse.... Better than the eyeball test. If you have no power there it could be the firewall connector itself. Seen some of them melted too. Work your way towards the battery until you find some power.
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Old 12-29-2013, 11:50 AM   #5
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Re: electrical issues

Sounds like the accessory side of the ign. switch may be bad or a loose connection on it. When the switch is turned to start position the acess. side is turned off.
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Old 12-29-2013, 12:19 PM   #6
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Re: electrical issues

He wouldn't have power to the distributor though... Would run in crank position. But not on/acc
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Old 12-30-2013, 05:16 PM   #7
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Re: electrical issues

Check the brown wire at the ignition switch, everything you listed is powered by the brown wire. The engine will still run because the ignition gets power from the pink wire.
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Old 12-30-2013, 05:36 PM   #8
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Re: electrical issues

Double post.
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Old 12-30-2013, 06:22 PM   #9
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Re: electrical issues

Just for illustrative purposes I decided to post up the wiring of the ACC brown wire that the fellows are talking about. I think they have it nailed down and you'll be able to see that in the diagrams.The first one shows the ignition switch wiring and the 12 gauge brown ACC wire on the switch.

Name:  60GMCRegulator.jpg
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Size:  108.2 KB


This one shows the ACC wire going to the fuse panel and feeding the Heater,wiper,and turn signal fuses. It is indicated by the black arrows.
The brown wire near it is the heater switch feed wire, the yellow wire is the windshield wiper motor wire, and the purple wire is for the turn signals. It runs from the fuse panel to the steering column connector and up to the turn signal switch.

Name:  Cab-1web.jpg
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Old 12-30-2013, 06:39 PM   #10
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Re: electrical issues

Great info guys
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Old 12-30-2013, 10:56 PM   #11
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Re: electrical issues

yes, exactly I will look further into this tomorrow
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Old 01-01-2014, 01:23 PM   #12
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Re: electrical issues

Okay, I looked further into it, and I believe that the brown wire is pulled mostly out of the ignition switch but it seemed too small of a wire to run all of that stuff. Also it still is partially starched to the switch and with the key on, it accidentally hit the dash and sparked but won't do it again, and no fuses are blown either never mind that was the brown white, anyone know what that goes to?
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Old 01-01-2014, 01:38 PM   #13
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Re: electrical issues

The only wired I have starched to the switch are: red pink purple brown-white and a light brown wired probably about 20 ga the only 12 ga solid brown wire I see goes straight to the heater controls
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Old 01-01-2014, 01:43 PM   #14
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Re: electrical issues

The Brown/White is the resistance wire going to the voltage regulator. The Brown wire should go to the same terminal. In the pic below it shows 2 brown wires on the terminal next to the purple wire, that is where both the brown and brown/white wires should be terminated.

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Old 01-01-2014, 01:52 PM   #15
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Re: electrical issues

Okay, that helps but I still can't find the brown ire under the dash, which is confusing me, but would that spark to the brown-white wire have possibly knocked out my voltage regulator?
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Old 01-01-2014, 01:54 PM   #16
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Re: electrical issues

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Originally Posted by 1968k10blue View Post
The only wired I have starched to the switch are: red pink purple brown-white and a light brown wired probably about 20 ga the only 12 ga solid brown wire I see goes straight to the heater controls
That wire is coming from the fused side of the fuse box, there should be another brown wire coming from the hot side of the fuse box going to the ignition switch. Look around, I suspect it probably broke off from the terminal.
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Old 01-01-2014, 01:57 PM   #17
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Re: electrical issues

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Originally Posted by 1968k10blue View Post
Okay, that helps but I still can't find the brown ire under the dash, which is confusing me, but would that spark to the brown-white wire have possibly knocked out my voltage regulator?
No you should be OK the Brown/White wire is a 24 GA resistance wire which would limit current flow. I would disconnect the plug at the iggy switch and check for dirt corrosion (high resistance) on the connectors.

Try tracing the brown wire from the fuse box and work your way back to the switch. It could be that a PO changed the wire color in a previous repair.
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Old 01-01-2014, 02:00 PM   #18
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Re: electrical issues

I would assume that this acc wire would still come from the main wire bundle that does up and around the steering column, and if this is the case there is only 1 12 ga wire coming from there which goes straight to the heater controls
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Old 01-01-2014, 02:02 PM   #19
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Re: electrical issues

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Originally Posted by 1968k10blue View Post
I would assume that this acc wire would still come from the main wire bundle that does up and around the steering column, and if this is the case there is only 1 12 ga wire coming from there which goes straight to the heater controls
Start at the fuse box and work your way back to the switch. It could be that a PO changed the wire color in a previous repair.
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Old 01-01-2014, 02:05 PM   #20
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Re: electrical issues

Will do but I may as well ask, there are repeat wired connected to a connector and only one wire coming our the other end and that not connected to anything, any ideas what that would be for?
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Old 01-01-2014, 02:14 PM   #21
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Re: electrical issues

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Originally Posted by 1968k10blue View Post
Will do but I may as well ask, there are repeat wired connected to a connector and only one wire coming our the other end and that not connected to anything, any ideas what that would be for?
Impossible to tell without seeing it because it is not stock and probably part of a PO hack job. Best thing to do is to identify all the wires and with the schematic find out where they are supposed to go to, then correct things from there bringing it back to stock. If you don't have a schematic PM me your e-mail address and I'll send you one, I tried to attach it but it is too big.
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Old 01-01-2014, 02:18 PM   #22
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Re: electrical issues

That what I figured but what I don't get is everything worked fine until Saturday night so if it is the ignition switch there should be a wire somewhere near it
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Old 01-01-2014, 02:21 PM   #23
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Re: electrical issues

Here is a slightly crappy photo of my ign.
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Old 01-01-2014, 04:57 PM   #24
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Re: electrical issues

Problem solved, loose connection at the fuse box
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