Author Topic: Wiring Diagram needed  (Read 1973 times)

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Offline AmericanMuscle

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Wiring Diagram needed
« on: January 07, 2007, 07:26:48 PM »
Sorry to ask this, but I can't seem to find my repair manual. My temp. gauge is not working, and as the wiring in my car has been butchered, I want to make sure everything is wired correctly. I already changed the temperature sending unit. If anyone has a diagram for a 79 301 4 barrel that you could post, I would appreciate it.

Offline Rick

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Wiring Diagram needed
« Reply #1 on: January 07, 2007, 07:44:51 PM »
I don't have the diagram you need, but I'd ask a question -- does the gauge seem to be connected to the wire on your sending unit?  In other words, what happens to the gauge when you disconnect the sending unit?  Any change in the gauge at all? :?   Or are you thinking that the wire may not be connected at all to where it should go (or worse, maybe to someplace it shouldn't go)?

Offline ta78w72

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Wiring Diagram needed
« Reply #2 on: January 07, 2007, 08:17:31 PM »
Unplug the green wire from the sending unit and with the key on, ground it.  The temp gauge should read all the way hot.  If you just unplug that green wire, with the key on, the temp should read all the way cold.

If it doesn't do that, you have only two wires to deal with.  The green wire, which comes in at pin number 13 on the white cluster connector, or the pink wire which comes in at pin number 5 of the cluster connector.  

With an Ohm meter, check the green wire for continuity.  If the Ohm meter indicates a break (no circuit) in the green wire, replace the green wire or find the break and fix it.

Check pin number 5 for 12 volt with the key on.  If your oil gauge works, you can skip this step, because the oil and temp gauge share the circuit.

If the green wire checks out, and if you have 12 volt on the pink wire (or if your oil gauge works), you have a break in the laminated plastic circuit on the back of the cluster.  You'll have to pull the cluster to fix it.

I have a paper that describes how to test the gauges as well as pull the cluster.  PM me if you want a copy.

It's almost never the gauge.

Offline AmericanMuscle

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Wiring Diagram needed
« Reply #3 on: January 07, 2007, 09:12:23 PM »
Thanks for the ideas. I havent tested the wires yet, so I will give that a shot tomorrow if I get a chance. The last owner put a Summit gauge in, so I want to route the wires back up to the old gauge. The Summit setup has a gauge for oil pressure and a gauge for the temperature right beside it; the oil gauge is working, but the temperature gauge is not. I don't know if the old gauge works or not, im guessing that it probably doesnt since he put in a new gauge, but the last owner wasnt very smart to begin with :?. The RPM gauge isnt working either and ive got some random wires dangling inside of the dash, so I feel like it's probably a big wiring mess.

Offline ta78w72

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Wiring Diagram needed
« Reply #4 on: January 07, 2007, 09:31:43 PM »
The information I gave you was for a stock setup.  However, now you know what pins in the cluster connector to deal with.  By the way, the blue wire from the oil pressure sender should route to pin number 8.