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1968 Cluster wiring vendor and specs?

Bobsdad

Well-known member
Joined
Nov 14, 2021
Messages
124
Hi folks,
Anyone know the gauge of wiring used behind the instrument cluster? Online and in my Scott Drake diagram book I only see info on the wire colors. If you're aware of a book or website where I can find more info on original / concours correct wiring gauges that'd be perfect.

Also, if you could recommend a place to get correct color and gauge wiring that'd be fantastic. Thanks.

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Ruppstang

Well-known member
Joined
May 22, 2009
Messages
3,080
Hi folks,
Anyone know the gauge of wiring used behind the instrument cluster? Online and in my Scott Drake diagram book I only see info on the wire colors. If you're aware of a book or website where I can find more info on original / concours correct wiring gauges that'd be perfect.

Also, if you could recommend a place to get correct color and gauge wiring that'd be fantastic. Thanks.

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Are you needing some wire to repair you original? I have a few original around if you need one.
 

franklinair

Well-known member
Joined
Mar 1, 2007
Messages
4,744
As an alternative depending on your need- Google Midlife Harness. He does excellent work, reasonable $$.

Neil
 
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Bobsdad

Well-known member
Joined
Nov 14, 2021
Messages
124
Are you needing some wire to repair you original? I have a few original around if you need one.
Thank you so much that'd be amazing. Based on my Scott Drake wiring diagram book I believe I need Black-white stripe wire and Yellow-White stripe.

My fuel gauge is stuck and I believe it's a wiring problem. I hooked up a 9V Battery to the back of the gauge and it swept the needle so I think the guage is fine. I had a shop tell me they are extremely confident it's not the sending unit (I forget how they tested it exactly).

It looks like the gauges are connected or daisy chained but they appear to be functioning normally so I assume it's one of these two wires. I haven't checked the wires for continuity but figured this would be an easy place to start versus the 20 guage black-violet stripe wire that it looks like runs from the sending unit to the cabin.
23e60be9b228be058add6fa78f544dbf.jpg


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Ruppstang

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Joined
May 22, 2009
Messages
3,080
Have you tested or replaced the low voltage regulator on the back of the cluster that those wires attach to? Is it only the fuel gage and not the oil pressure gage? If oil pressure is ok then the regulator is ok.
 
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Bobsdad

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Joined
Nov 14, 2021
Messages
124
Have you tested or replaced the low voltage regulator on the back of the cluster that those wires attach to? Is it only the fuel gage and not the oil pressure gage? If oil pressure is ok then the regulator is ok.
Yes, I replaced the regulator a couple weeks ago. It looks to me like the oil pressure gauge is working OK.

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Mosesatm

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Joined
Jan 18, 2005
Messages
9,177
The wire that goes from the sender to the front of the car tends to break at the tank.
 
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Bobsdad

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Nov 14, 2021
Messages
124
The wire that goes from the sender to the front of the car tends to break at the tank.
Thanks, Arlie. Looks like checking continuity of that wire might be best to do first.

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franklinair

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Joined
Mar 1, 2007
Messages
4,744
Do me a favor:
1.) Remove the wire from the Fuel Sending Unit, and turn the Ignition key to the ACC position. The fuel gauge should read empty.
If it does not read empty, the wire from the Sending Unit is Grounded somewhere leading to the Gauge.
2.) If the Gauge is reading empty, ground the Sending Unit wire. The Gauge should then read Full.
3.) If both of these tests are OK, the Sending Unit is bad.

Neil
 
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Bobsdad

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Joined
Nov 14, 2021
Messages
124
Do me a favor:
1.) Remove the wire from the Fuel Sending Unit, and turn the Ignition key to the ACC position. The fuel gauge should read empty.
If it does not read empty, the wire from the Sending Unit is Grounded somewhere leading to the Gauge.
2.) If the Gauge is reading empty, ground the Sending Unit wire. The Gauge should then read Full.
3.) If both of these tests are OK, the Sending Unit is bad.

Neil
Thank you, Neil. The gauge doesn't read empty when the wire is disconnected with the key on. It does go to full when the wire is grounded via jumper at the U Bolt.

I take it this means the wire needs to be replaced? Or at least, find the bad spot and splice in a replacement section?

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franklinair

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Mar 1, 2007
Messages
4,744
With the sender wire disconnected, and the key On, what does the gauge read?

Neil
 

franklinair

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Joined
Mar 1, 2007
Messages
4,744
Here's a thread I sent a few years ago. May be of help to anyone working on wiring.
Do a thread search for Wiring Info posted by franklinair, I think in 2019.
I just now posted it on Facebook.

Neil
 
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Bobsdad

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Nov 14, 2021
Messages
124
I also put a test light into the push connector and the light did come on but barely. I believe it's also supposed to pulse but it was just constant and dim. I take that as more evidence the wire is cracked?

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Bobsdad

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Joined
Nov 14, 2021
Messages
124
Here's a thread I sent a few years ago. May be of help to anyone working on wiring.
Do a thread search for Wiring Info posted by franklinair, I think in 2019.
I just now posted it on Facebook.

Neil
Found it! Very helpful, I'm going to save it and print a copy for my garage. Thanks again!

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franklinair

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Mar 1, 2007
Messages
4,744
I'm still curious: What did the Fuel Gauge read specifically with the Sender wire disconnected and Ign Switch On?

Neil
 
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Bobsdad

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Nov 14, 2021
Messages
124
I'm still curious: What did the Fuel Gauge read specifically with the Sender wire disconnected and Ign Switch On?

Neil
Hi Neil,
It read about a quarter tank full which is where the needle has been sitting for at least 3 years. I guess there's a chance it *would* have dropped to empty but the needle is stuck there. But if it's stuck I wouldn't have expected it to sweep up to full.

What do you think? Also, I'll give you a call this afternoon.

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Bobsdad

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Nov 14, 2021
Messages
124
Are you sure the float isn’t stuck or saturated?
Hi Arlie, sort of. The shop that tuned the carb checked it out and told me they were reasonably sure three problem wasn't at the tank. Although I can't remember exactly what they did their explanation sounded solid at the time. I'm planning on replacing the tank this summer anyways so maybe I'll just do that sooner than later and see if replacing all that does the trick.

But you were right about the wiring condition near the tank of course. When I was down there yesterday it was pretty crusty and nasty. I believe I saw somewhere that wire is 20 guage - currently I'm thinking of buying a bit and splicing it in the trunk behind the seat and seeing if that'd work as a temporary fix. I want to upgrade the wiring for the whole car this coming winter.

I've never done wire splicing or anything like this so if you have suggestions or resources you think would be good for a newbie I'd love to see. Thanks.

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