Author Topic: Screwy Wiring  (Read 2168 times)

Offline 78 Chevyrado

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Screwy Wiring
« on: April 09, 2011, 09:03:58 PM »
Just had a problem spring up tonight.  I don't know exactly when it started, but it was sometime today.

The dome light and cargo light don't work at all, and the bulbs are good.  The courtesy light under thew dash works, BUT whenever the courtesy light under the dash is on, the cigarette lighter and radio cut off.  But when the courtesy light under the dash goes back off, instantly the radio and cigarette lighter work fine again.  At the time I DID have my cell phone charger hooked up to the cig lighter.  That may have been what screwed it up, but I'm not sure.  I've been riding around all day  back and forth in the daylight with the radio off, so who knows when it started.

I guess I'll be checking it out tomorrow, so any ideas what could be causing this to save me a little bit of time?  Everything else electrical seems to be working correctly.  all lights but the dome and cargo come on, gauges and their lights work, volt gauge is fine.  

Also whenever the courtesy light under the dash comes on, cutting off the radio, it makes a deep bass thump in the speakers as the radio cuts out.

I haven't been doing anything funny to the truck, and haven't been working on anything lately, I have been hauling lots of loads of junk through the woods and it's rough back there.  maybe something jiggled loose?  thats all I can come up with so far.


Thanks fellas
Kenny
« Last Edit: April 09, 2011, 09:06:20 PM by 78 Chevyrado »
Kenny

1978 C-20, 350/400, 3.73, Graystone Metallic, Raceline Renegade 8 Wheels - 18x8.5, 275/70R18 BFG KO's

Offline bake74

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Re: Screwy Wiring
« Reply #1 on: April 09, 2011, 09:22:44 PM »
     The first place I would check is the fuse block to see if somehow the lights you said were having problems and the radio didn't somehow short out between the circuits.  It really sounds like somehow the circuits affected got a short between them, maybe from all the bouncing around you said you were doing.  Good luck and keep us posted.
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Offline 1979C20

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Re: Screwy Wiring
« Reply #2 on: April 10, 2011, 02:27:58 AM »
Im pretty certain the over head light and the cigarette lighter are on the same fuse, and I had a short in the cigarette lights. It PARTIALLY blew the fuse. My over head light wouldnt work and my cigarette lighter turned on and off repeatedly. The fuse was hardly making contact. Check all of your fuses.
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Offline beastie_3

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Re: Screwy Wiring
« Reply #3 on: April 10, 2011, 11:19:20 AM »
Check your grounds as well. I believe the ground for this is on the emergency brake bracket, up near the top. There are 5 or 6 tabs which ground wires clip onto.

Online zieg85

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Re: Screwy Wiring
« Reply #4 on: April 10, 2011, 12:52:44 PM »
Related to but not exactly the same... My 1985 C20 every once in a while will blow out the horn fuse.  That effected the dome light but not the light under the dash.  The cigarette lighter was effected because the radar detector would go on and off when the door switch activated the dome lights.  Somehow they were all effected and if your power to the aftermarket radio was taken from the cigarette lighter circuit that may be what is happening.  As long as the fuse is good and the horn works everything else is fine.  My $.02
1985 C10 Custom Deluxe 4.1L 3 on the tree
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 4.56 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 Custom Deluxe 5.7L 3 on the tree 2.73

Offline 78 Chevyrado

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Re: Screwy Wiring
« Reply #5 on: April 10, 2011, 06:21:52 PM »
Related to but not exactly the same... My 1985 C20 every once in a while will blow out the horn fuse.  That effected the dome light but not the light under the dash.  The cigarette lighter was effected because the radar detector would go on and off when the door switch activated the dome lights.  Somehow they were all effected and if your power to the aftermarket radio was taken from the cigarette lighter circuit that may be what is happening.  As long as the fuse is good and the horn works everything else is fine.  My $.02

That sounds exactly like mine, Just I had a phone charger hooked up in place of your radar detector.  I didn't find anything wrong so I put another fuse in it and now everything is fine.  Everything wil run at once and works perfectly.  The fuse was clearly blown right in the middle, so who knows.  The radio power explanation sounds like that may be it.  I can't remember how it's hooked up, but if I was able to, I'd have used the stock radio wires.

Thanks for the help guys.  I at least know it's not a big deal.  I just never had one do something like that unless it had been wired badly to begin with.  Yall helped  a lot!

Kenny
Kenny

1978 C-20, 350/400, 3.73, Graystone Metallic, Raceline Renegade 8 Wheels - 18x8.5, 275/70R18 BFG KO's

Online zieg85

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Re: Screwy Wiring
« Reply #6 on: April 10, 2011, 06:43:50 PM »
Glad I could be of some help.  Yours is the best 73-79 I have ever seen. 
1985 C10 Custom Deluxe 4.1L 3 on the tree
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 4.56 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 Custom Deluxe 5.7L 3 on the tree 2.73

 


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