Wire colors and locations ??

[mtnmankev]

After installing the donor wiring harness, I find the temperature gauge doesn't work, and the oil pressure gauge isn't indicating despite a new sending unit.
And the dome light refuses to light despite grounding the terminal that plugs into the door switch or twisting the headlight switch.
I would like to find a diagram or picture of the fuseblock connector on the engine compartment side showing which terminal is oil pressure and coolant temp, and the color of the wires, and also the connector that plugs into the instrument cluster identifying the location and color of the wire for the temperature gauge so I can test for power into those circuits.
I'm open to suggestions where to look for the issue on the dome light, I verified the terminal on the fuseblock is live power full time.
Thanks in advance, Kev

 

[Scott91370]

Check here: https://www.gmsquarebody.com/threads/1973-1991-wiring-manuals.14498/

 

[Raider L]

I have a schematic for my '74 C10 which is the same for the '73 C10. Let me take photo of it and I'll put it up for you. I got a factory manual from my local Chevy dealer before I rebuilt my truck because I planned on going front to rear checking every wire. Also, I was removing the printed circut board and "gang plug, the thing you want to see, and I was planning on putting in mechanical gauges replacing all the idiot lights and gauges that ran off the printed circut. Let's see if I can get this on one photo. Coming up! Hope this helps!

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[mtnmankev]

Thank you, I did manage to get what was supposed to be the diagram for the 82/83 and found a yellow wire to the gang plug and that color wire didn't show up on the diagram.
So, this truck is turning into an interesting challenge.
Several wire colors and locations did not match the supposed 82/83 diagram.
My roomie was able to crawl under the dash and checked out the gang plug for me as we tried to locate which color wire went where, and he noticed the edge of the PC board was crinkled at one spot and the plug wasn't making connection.
After he carefully put the plug back in, the temperature gauge started working again, but the oil pressure is still being a turd and not wanting to play nicely and indicate any pressure.
Since I have the electric fuel pump wired to the sending unit, as long as the engine is getting gas and running, I know it has oil pressure, but I like to be able to monitor how much and when.

 

[Raider L]

mtnmankev, Do you know how to read the color codes for the wire? It's relatively simple. Take the second photo: At the gang plug, "20DBL" This means a #20 size wire and Dark Blue in color, i.e. D-Dark, BL-Blue. The number afer the color is it's location in the fuse block. Don't worry about that right now because that wire is probably in the wrong place anyway. So let's look at another one on the same block: next one down same side, "20LBL". That's #20 size wire Light Blue or L-Light, BL-Blue.
On the other side at the gang plug there is "20P". That means #20 size wire, Purple, or P- purple, etc. R- Red, DG- Dark Green, T- Tan. Same photo there is a "18B/W" That's a #18 size wire Brown with a White stripe together down the wire. Some will be LGN/W which is Light Green with a white stripe on the wire. Like that Hope these aren't to confusing. I was an aircraft mechanic for seven years and had to learn how to read schematics. You think our trucks are confusing you ought to see a jet schematic, it's a mind blower if you weren't used to it or have a patient person to teach you.

 

[Dave M]

Oil = blue, Temp = green, Under dash the orange should have 12v + , to feed the dome lights, pink is ignition power 12v +, voltmeter and ammeter wiring differs,

 

[Raider L]

Oh, okay. I wasn't aware it was for a 80's truck. I must have missed that somewhere. Never mind!

 

[Raider L]

When I followed all the wires to my fuse block I found out that NONE of them were where the schematic indicated they were. All the wires came out totally different than the drawing showed. I just went where the wires were at the gang plug and where they went. I would have to take all the wires out of the fuse block in the cab and rewire them where they are supposed to be. Not right now please!

 

[Dave M]

Thank you, I did manage to get what was supposed to be the diagram for the 82/83 and found a yellow wire to the gang plug and that color wire didn't show up on the diagram.
So, this truck is turning into an interesting challenge.
Several wire colors and locations did not match the supposed 82/83 diagram.
My roomie was able to crawl under the dash and checked out the gang plug for me as we tried to locate which color wire went where, and he noticed the edge of the PC board was crinkled at one spot and the plug wasn't making connection.
After he carefully put the plug back in, the temperature gauge started working again, but the oil pressure is still being a turd and not wanting to play nicely and indicate any pressure.
Since I have the electric fuel pump wired to the sending unit, as long as the engine is getting gas and running, I know it has oil pressure, but I like to be able to monitor how much and when.

You've totally lost me, how can you have the fuel pump wired to the fuel sender unit ? Also, it is nice to monitor oil pressure, but you can't watch it all the time. I fitted also what is commonly known as the "idiot light" in my oil gauge face, you can also say it is "fool proof"

 

[mtnmankev]

You've totally lost me, how can you have the fuel pump wired to the fuel sender unit ? Also, it is nice to monitor oil pressure, but you can't watch it all the time. I fitted also what is commonly known as the "idiot light" in my oil gauge face, you can also say it is "fool proof"

I put a "T" between the sender and the engine block.
Got a pressure switch from NAPA and as long as the engine has oil pressure, it passes voltage to the electric fuel pump.
It runs through a SPDT center off toggle switch hidden under the dash.
I can select fuel when oil pressure is present, fuel pump all the time (makes priming the carb a cinch) or no fuel at all (center off).
It adds a touch of anti theft security when the truck can't get out of a parking lot with no fuel supply.

 

[mtnmankev]

You've totally lost me, how can you have the fuel pump wired to the fuel sender unit ? Also, it is nice to monitor oil pressure, but you can't watch it all the time. I fitted also what is commonly known as the "idiot light" in my oil gauge face, you can also say it is "fool proof"

And as for watching the gauges all the time, it's just part of driving.
I am one of those rare few drivers who constantly glance at the gauges to make sure nothing is awry, I listen for any sounds, either normal or unusual, and I am aware of everything going on around me, from what's behind me, to both sides and way down the road in front of me as far as I can see.
There's too many idiot drivers loose on the roads not to pay attention all the time.

 

[Dave M]

I put a "T" between the sender and the engine block.
Got a pressure switch from NAPA and as long as the engine has oil pressure, it passes voltage to the electric fuel pump.
It runs through a SPDT center off toggle switch hidden under the dash.
I can select fuel when oil pressure is present, fuel pump all the time (makes priming the carb a cinch) or no fuel at all (center off).
It adds a touch of anti theft security when the truck can't get out of a parking lot with no fuel supply.

That's makes sense, I'm with you now. I also run an electric fuel pump in mine, I wired it through an electronic relay which is activated by the ignition tach' pulse. It automatically runs the pump for priming, for 3 seconds, when you switch on the ignition. It's also a good circuit to install an anti theft system.
As for me, l also like to monitor the gauges and be conscious of my vehicle and surroundings, but l had the experience of the oil pickup dropping off my BB. The mechanical gauge doesn't react that quick. The little LED light l fitted is discreet , yet it's an attention getter.