Instrumental panel electrical problem. 77 gmc 1500

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Sepulvd

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El cajon
First Name
David
Truck Year
1977
Truck Model
1500
Engine Size
454
Half my gauges are working. Currently the speedo and temp aren't working. But oil, volts and fuel work perfectly. Are the speedo and temp connected to the same terminal board trying to trace it to the schematic but can seem to find the speedo.
 

Bextreme04

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Oregon
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Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
Speedo is purely mechanical. Its driven by a cable that goes to either the transmission on a 2wd or the transfer case on a 4wd.

Temp sensor is a single wire going to a sensor on the drivers side head. Is the gauge pegged high, pegged low, or not moving at all when you turn the ignition on?
 

Sepulvd

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El cajon
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David
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1977
Truck Model
1500
Engine Size
454
Temp is pegged high. Make sense about the speedo. It had a 6 cyl and now has a 454 maybe the dude never install the cable again
 

Sepulvd

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Posts
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Location
El cajon
First Name
David
Truck Year
1977
Truck Model
1500
Engine Size
454
Speedo is purely mechanical. Its driven by a cable that goes to either the transmission on a 2wd or the transfer case on a 4wd.

Temp sensor is a single wire going to a sensor on the drivers side head. Is the gauge pegged high, pegged low, or not moving at all when you turn the ignition on?
Well had a chance to search for the wire on the temp Guage. It's not there at all. Going to have open the dash and see if i can trace it or just run a new wire
 

Raider L

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William
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1974
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C10
Engine Size
355
@Sepulvd,

I worked with a guy from your family many, many years ago. He was from Zwolle, LA.
Like my last name, somewhere we're all related. I recognized the spelling. No one else would recognize that name unless you were from Louisiana. You just didn't finish spelling it and I won't do that, I respect your privacy.

Anyway, that wire has to be somewhere down there, the PO wouldn't just rip it out of the bundle. You have the schematic, look and see what color it is and look for that down there. You said something about it, do you have a sending unit in the block, but no wire right? I've got a similar problem the alternator field trigger wire, the one that lights up that red light on the dash when you first start the engine? That's a real important light. It tells you if there are any problems with the alt. The temp. wire to. My old radiator had holes in it and starting out everything was fine and after being gone for about fifteen minutes, I was a block from home and looked down at the gauge and it was 210! It scared me to death but by then I was about a half a block from the house when I saw it. No cracked gaskets though, thank God.
So, yeah, find that wire!
 

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