wiring harness replacement

airdog005

airdog005

Member
Oct 7, 2022
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North west Chi. suburb.
Hi Folks,
1977 Birchaven, I have a new instrument panel and would like to replace the wiring harness ( no sense in putting new wires with old)
Has anyone accomplished this or know of any shop that has?
Thanks
 
I’m not aware of a factory wiring harness kit (doubtful with low production volumes) but I’m in the opposite boat. Previous owner had the OEM dash replaced with largest available Mac Dash. Sounded great when I was shopping for a GMC but I‘ve learned to hate the aftermarket dash every time I whack my knees on the legroom it consumed. The rewiring was a hack job with spaghetti wire and masking tape labels that mostly crumbled and vanished.

My advice for what it’s worth: stay with factory wiring colors if possible.
 
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I agree with sticking to OEM wire colors. I have a MAC instrument panel but not the whole dash replacement. The original instrument panel was replaced with a MAC instrument panel back in 1989 but I am not a fan of burled wood grain and black background with black needles on the gauges. I had a newer MAC Instrument panel built but I fret removing the old panel based on the nightmare wiring I found around the fuse panel that I had to fix. One of these days I will dive in and replace the instrument panel. Attached is my replacement.
IMG_3242.jpeg
Here was what I had to clean up:
IMG_3911.webp
 
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If I had to replace the wiring in mine I’d go with one of the Painless Wiring kits. I helped my brother rewire his ‘76 C30. You still need to do lots of crimping. If you follow the manual it then becomes your wiring diagram.
 
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Hi again,
I might have found a wiring harness supplier. Custom Auto Wiring in Ohio.
I need to have some pictures and such then if I decide to go with them send in the harness and they would give a final estimate (any where from $600.00 to $900.00) depending on available plugs and such.
Just asking if anyone has a donor coach that might have the harness that is no good for anything except for color coding on wire and length.
Peace
 
74_Coach said:
I agree with sticking to OEM wire colors. I have a MAC instrument panel but not the whole dash replacement. The original instrument panel was replaced with a MAC instrument panel back in 1989 but I am not a fan of burled wood grain and black background with black needles on the gauges. I had a newer MAC Instrument panel built but I fret removing the old panel based on the nightmare wiring I found around the fuse panel that I had to fix. One of these days I will dive in and replace the instrument panel. Attached is my replacement.
View attachment 11375
Here was what I had to clean up:
Click to expand...
do you have a part number or reference information for that dash kit? my gauges are in dire need of replacement..

thanks!
 
cbirky said:
do you have a part number or reference information for that dash kit? my gauges are in dire need of replacement..

thanks!
Click to expand...
Yes - http://www.custominstrumentpanels.com/gmc.htm

You can look through all of the instrument panel designs on that page but the gauges are posted off the tiny main menu - look for CIP Home.

If you don’t like the CIP selection of gauges, check out this website: https://classicdash.com/product-category/veethree-gauge-sets/

The Elite Series White Sterling breaks up all that white background but still keeps it readable. For the fuel gauge, you will want to select 0-90 OHM.

Ed
 
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I'll start a private conversation with you and get the details for shipping and payment.
Look in the upper right corner and you will see an envelope icon. When you receive a conversation, a number will appear on the envelope. Just click on the envelope and it will open. I hit the like button, and you should have a red 1 on the bell. This to illustrate what it would look like on the envelope.
 
Mine came with an uninstalled Mac dash but old dash removed and ready for install.
First thing I did was remove all the old, added on wiring for the coach.
Then, I made a bunch more harnesses, added terminal blocks, relays, etc. Despite zip ties and such, it's still a pretty packed scenario. I kind of think that's inevitable, especially with the changes to RV electrical systems.

My advice would be to solder and heat shrink every connection for the most trouble-free attachment.
There's a recent thread on the forum about wiring labels. Definitely the way to go. I already don't remember lots of what goes where.
 
GMCMI Fall 2026 Rally
Applied GMC

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