Can't find the main ground for dash wiring on a '75

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Can't find the main ground for dash wiring on a '75

Post by burners on Tue May 31, 2011 2:23 pm

I've been fixing various wiring issues this past week. The one thing that has me at a loss is the main ground point for the entire harness. I can't find the physical location. All the black wires just disappear into the harness. Here is a photo with the point that I'm talking about.


Just so you know how serious I am...the car currently looks like this. Shocked Lol.

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Re: Can't find the main ground for dash wiring on a '75

Post by texan01 on Tue May 31, 2011 3:15 pm

I think it grounds to the sheetmetal by the fusebox.

What isn't working on it?

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Re: Can't find the main ground for dash wiring on a '75

Post by burners on Tue May 31, 2011 3:24 pm

The dash lights, cig. lighter don't work and some of the gauges are acting funny. It looks like I have several ground wires that have broken but I can't trace them. I looked around the fuse box and checked out all the black wires near it and none seem to be it. Also, I notice that I don't get a good ground on the body. Only the steering column seems to be well grounded. I'm experiencing this as I use a meter to check power on various wires. Going to the body won't work but going to the column will get me a reading.

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Re: Can't find the main ground for dash wiring on a '75

Post by pila on Tue May 31, 2011 8:47 pm

The grounding point is near where the bottom dash attach point is, on the driver's side. On my '75 Elco it's grounded on the body near the end of the dash. I made a new ground post there, with a stainless steel 3/16" bolt, with the head on the back side, and the threaded end protruding, to ground other items besides the main harness ground. The main ground is a black wire that comes from inside the harness bundle, which you likely have hanging there.

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Re: Can't find the main ground for dash wiring on a '75

Post by texan01 on Tue May 31, 2011 9:37 pm

I had to redo the chassis ground on mine, the wire from the negative terminal on the battery had just about burnt in two, so I added a braided steel strap on the back of the engine to the firewall.

Much better voltage throughout the car, fixed my really dim interior lights, and the dramatic sags when you'd hit the brakes or used the turn signals.

i'd go with Pila's suggestion and add a new dash ground. If you've got the grounds sorted out in the harness, then just add a new ground to it. Make sure your chassis ground is good as well.

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Re: Can't find the main ground for dash wiring on a '75

Post by 1973 454 MONTE on Wed Jun 01, 2011 7:33 pm

it seems to me that the connection in your circle is a connection in the harness (maybe twisted and taped). if you look to the right of your circle you will see a 0 with a + at the bottom. that i do believe is the one wire that bolts to the left lower dash bolt. i have taken 20 or so dashes out,and cant think of another ground connection under the dash. i lust looked at my 73 and there is one eyelet that is bolted to the 7/16 bolt. just my $0.02
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Re: Can't find the main ground for dash wiring on a '75

Post by pila on Wed Jun 01, 2011 9:29 pm

That's what I figured also. It's an 18 gauge wire, so it likely supports the grounds in the big splice in the bundle. Sometimes the splice is soldered together.

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Re: Can't find the main ground for dash wiring on a '75

Post by 1973 454 MONTE on Wed Jun 01, 2011 9:44 pm

have you tried another harness to get rid of your problem?
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Re: Can't find the main ground for dash wiring on a '75

Post by 1973 454 MONTE on Wed Jun 01, 2011 9:47 pm

[quote Lol.
[/quote]

scratch is there NO front windsheild in that automobile?????????????????? scratch
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Re: Can't find the main ground for dash wiring on a '75

Post by burners on Tue Jun 14, 2011 10:59 pm

Thanks guys. I think I have it figured out now. I'm putting the dash back in now. We'll see how things work. I managed to find several things unplugged and a few other failures that caused the power windows to stop working so I've had some success so far.

1973 454 MONTE, there is a windshield installed. That is just a sun shade you see in the photo.

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Re: Can't find the main ground for dash wiring on a '75

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