Need help with gauge wiring

[tatastruck]

I am trying to get my water temp gauge working of my 64 fleetside so I can get rid of the ugly aftermarket one. My father in law beat this truck to **** and let rinky-dink mechanics jury-rig any thing so he could get to work...The green wite coming off of the instrument cluster harness isn't connected to anything. Where or what is this supposed to be connected to it. there are many more also the thrift heater switch has one of its wires cut. I have included pics below. Any help would be great!

[tatastruck]

Bump!

[FetchMeAPepsi]

I wont have Cecilia apart again until this weekend. If no one chases it by then I'll take some pix and show you where they go if my alzheimers doesnt get in the way lol.
send me a pm reminder if I forget

[tatastruck]

I wont have Cecilia apart again until this weekend. If no one chases it by then I'll take some pix and show you where they go if my alzheimers doesnt get in the way lol.
send me a pm reminder if I forget

Thanks

[Andice]

Dark green 20 ga wire runs to the bulkhead connector. From there it goes to the temp sender.

[Andice]

If that cut heater wire is 14 ga brown then it runs directly to the fuse panel and plugs into the side of 10 amp fuse marked "heater"

[tatastruck]

Thanks everyone for your help. I would like infoe on what color the wire is in engine compartment and where it's located and where sender should go. See photo

[tatastruck]

Forgot pic

[raycow]

It looks like you have a mechanical temp gauge in there now. If the gauge is working and you don't mind its appearance, why not just go on using it? Experience on this and other forums has shown that the senders available now for the stock gauge aren't particularly accurate. GM doesn't make/sell the original sender any more.

Oh, now I see. You don't like the looks of the mechanical gauge. Sorry, I won't try to talk you out of changing it then.

Ray

[tatastruck]

Yeah. If it was mounted correctly in the cluster id leave it. It's mounted to the bottom of dash and I think it looks janky. If its too much work to get it working then so be it but I'd like a functional dash. So where should this dark green wire come out in engine compartment. Is there anyone in the Bay Area that would let me look at their truck as a reference?

[raycow]

My truck is a "brand C", and I couldn't find a GMC wiring diagram, so some of this is semi-guesswork. The dark green wire goes through the engine harness connector on the firewall, so start looking for it there, and then you can follow it to wherever it ends. If you can't identify the engine harness connector, look for the one that has wires going to the starter solenoid.

Ray

[raycow]

After looking at your pictures, I think the answer I gave you isn't the one you are looking for. In the first pic, is the round thing with wires coming out of it the instrument cluster connector? And are you saying the other end of the green wire is just hanging free and not connected to anything?

If yes to both, the quick and dirty fix: Extend that green wire, run it though any convenient hole in the firewall, and connect it to the temp sender.

The "correct" fix: Find the green wire on the engine harness firewall connector. On the cabin side of the firewall, run a new wire from that terminal of the firewall connector to the cluster connector. On the engine side, find the green wire and see if it is long enough to reach the sender. If it isn't, replace the wire with a new one.

If the above still isn't what you are looking for, please tell me what you need to know.

On the second pic, I have no idea what I am supposed to be looking for, and the pic is too fuzzy to see much detail.

Ray

[tatastruck]

After looking at your pictures, I think the answer I gave you isn't the one you are looking for. In the first pic, is the round thing with wires coming out of it the instrument cluster connector? And are you saying the other end of the green wire is just hanging free and not connected to anything?

If yes to both, the quick and dirty fix: Extend that green wire, run it though any convenient hole in the firewall, and connect it to the temp sender.

The "correct" fix: Find the green wire on the engine harness firewall connector. On the cabin side of the firewall, run a new wire from that terminal of the firewall connector to the cluster connector. On the engine side, find the green wire and see if it is long enough to reach the sender. If it isn't, replace the wire with a new one.

If the above still isn't what you are looking for, please tell me what you need to know.

On the second pic, I have no idea what I am supposed to be looking for, and the pic is too fuzzy to see much detail.

Ray

Ray you're dead on. The wire is broken and I can see both ends under the dash. I can't see where it comes out into engine compartment. That's what I need a pic of. I want to test the wire to see if there is contunity before I repair under the dash. So I need pics of where the sender is located and where the wire comes through firewall

[raycow]

Ok, the sender is easy. You already found where it goes. That's the place where the mechanical gauge is installed now. In other words, whoever installed the mechanical gauge removed the sender, so you need to get a new one.

For the wire, find the firewall connector. If GMC is like Chevy, it will be the one that has wires going to the starter solenoid. If nececessary, unwrap the connector end of the harness so you can see the color of the wires. You already know you are looking for the green wire, so follow it until you reach its end. On the cabin side look for the same terminal that the green wire is connected to on the engine side and connect your cluster wire to that one. That's all you need to do. As we rocket scientists like to say, "It's not rocket science."

Here are some Chevy wiring diagrams which might be of help.
http://www.64moneypit.pages.qpg.com/6066chevytrucks/id12.html
If anyone knows where GMC diagrams are, please be kind enough to post a link.

Ray

[FetchMeAPepsi]

I told you I'd forget! I got tied up with my steps this weekend and didn't think about anything but a shower and sleep afterward. I'll take some pics today.

The PO might have clipped that wire because the new senders don't run well with the old gauges. You have to put a resistor on them. See here for how I did it if you're going with the a NAPA sending unit. http://6066gmcclub.com/forum/showthread.php?p=47576
They're pretty cheap too so its an easy fix.

[FetchMeAPepsi]

Ok amigo, here's the wiring trail for both wires. Click for bigger pics.

The brown heater wire runs from the switch there on the outside of the wire highway (taped up wires) to the dash, then down to the fuse box like someone else said.

http://windypix.com/?dm=I0RP.jpg (http://windypix.com/?pm=I0RP)




It ends up at the box and plugs into the side of the heater fuse thingy with a black or brown plug. Mine is here on the wrong plug, yours should be one lower than this.

http://windypix.com/?dm=JCUP.jpg (http://windypix.com/?pm=JCUP)




Ok, now the sending unit wire. You already know it ends on the sending unit by the top water hose off of the radiator. You can get those at NAPA for a couple of dollars.

It starts behind the dash in the wire plug.

http://windypix.com/?dm=68SX.jpg (http://windypix.com/?pm=68SX)




This is a weird pic, but it's looking up between the radio and the dash cluster.

http://windypix.com/?dm=9P31.jpg (http://windypix.com/?pm=9P31)




Then it runs over behind the heater, hiding like a little girl.

http://windypix.com/?dm=2QJ5.jpg (http://windypix.com/?pm=2QJ5)




I shoved my phone up there and got a pic anyway. Take that Engineering department!

http://windypix.com/?dm=QRPJ.jpg (http://windypix.com/?pm=QRPJ)




It comes out of the firewall heahh, behind the coil.

http://windypix.com/?dm=L0CN.jpg (http://windypix.com/?pm=L0CN)




Then meanders down past the starter heahhh

http://windypix.com/?dm=NYAD.jpg (http://windypix.com/?pm=NYAD)




Then comes out Neahhhh with the alternator wiring (or gen if you have one). It's still dark green. And that's it. From here it just runs to the sending unit and plugs in. Tada!

http://windypix.com/?dm=MM7B.jpg (http://windypix.com/?pm=MM7B)





*disclaimer: Please don't blow yourself or your truck up by following my advice. It's probably all wrong anyway. :lolflag:

[6066gmcguy]

What you need is a maintenance manual or operators manual, they both have wire diagrams in them. check eBay. look for manual staring with 64....

[tatastruck]

Ok amigo, here's the wiring trail for both wires. Click for bigger pics.

The brown heater wire runs from the switch there on the outside of the wire highway (taped up wires) to the dash, then down to the fuse box like someone else said.

http://windypix.com/?dm=I0RP.jpg (http://windypix.com/?pm=I0RP)




It ends up at the box and plugs into the side of the heater fuse thingy with a black or brown plug. Mine is here on the wrong plug, yours should be one lower than this.

http://windypix.com/?dm=JCUP.jpg (http://windypix.com/?pm=JCUP)




Ok, now the sending unit wire. You already know it ends on the sending unit by the top water hose off of the radiator. You can get those at NAPA for a couple of dollars.

It starts behind the dash in the wire plug.

http://windypix.com/?dm=68SX.jpg (http://windypix.com/?pm=68SX)




This is a weird pic, but it's looking up between the radio and the dash cluster.

http://windypix.com/?dm=9P31.jpg (http://windypix.com/?pm=9P31)




Then it runs over behind the heater, hiding like a little girl.

http://windypix.com/?dm=2QJ5.jpg (http://windypix.com/?pm=2QJ5)




I shoved my phone up there and got a pic anyway. Take that Engineering department!

http://windypix.com/?dm=QRPJ.jpg (http://windypix.com/?pm=QRPJ)




It comes out of the firewall heahh, behind the coil.

http://windypix.com/?dm=L0CN.jpg (http://windypix.com/?pm=L0CN)




Then meanders down past the starter heahhh

http://windypix.com/?dm=NYAD.jpg (http://windypix.com/?pm=NYAD)




Then comes out Neahhhh with the alternator wiring (or gen if you have one). It's still dark green. And that's it. From here it just runs to the sending unit and plugs in. Tada!

http://windypix.com/?dm=MM7B.jpg (http://windypix.com/?pm=MM7B)





*disclaimer: Please don't blow yourself or your truck up by following my advice. It's probably all wrong anyway. :lolflag:

Dude! You're the man!

[tatastruck]

Does anyone have the part number for that NAPA temp sending unit?

[FetchMeAPepsi]

Yeah its in my build thread at the link I posted. Part number ECH TS6469
http://6066gmcclub.com/forum/showthread.php?p=47694#post47694

About 11 bucks.
Dont forget a resistor.

[tatastruck]

What resistance? I'm assuming it can be placed anywhere in that circuit?

[tatastruck]

Hey fetch me a Pepsi, do you know if that wire for the heater is supposed to have power with the ignition on I just don't want to hook it up and burn down my truck I think it supposed to have power but I'm not sure

[tommyduncan]

Fetchmeapepsi that was awesome work laying on your back, side, standing on your head etc... for a guy with a bad hip!

I can't say with certainty on a GMC but on virtually every other 60's and up car I've worked on the heater fan stays on with the key.

[tatastruck]

Ok so this is where I am....I fixed the temp gauge...fetchmeapepsi,If I'm ever up in WA, lunch is on me! This brown wire.... I believed I have traced it but I just want to verify...this is the single wire connector on the lower part of the fan switch. above it is a 3 wire connector. I just want to confirm that this single wire should have power with the ignition on

[FetchMeAPepsi]

That's right Tatastruck. It's a single brown wire on the bottom. Active with key on.

[Vernski]

Hey Fetch a pepsi you will like this, sometimes my wife thinks she's funny she bought me a T-shirt the other day and she's still laughing about it, it say's

"I HATE BEING BIPOLAR"

"IT'S AWSOME"

Vernski:lolflag:

[FetchMeAPepsi]

Hey Fetch a pepsi you will like this, sometimes my wife thinks she's funny she bought me a T-shirt the other day and she's still laughing about it, it say's

"I HATE BEING BIPOLAR"

"IT'S AWSOME"

Vernski:lolflag:

:toofunny:

Your wife sounds like my kinda gal. All I got when my wife went shopping was the bill :ahhhh:

Stupid back to school month is draining all my truck fundzzzzzz! Sorry for the thread hijack Tatastruck haha:lolflag: