Electrical Factory water temp gauge setup?

[AndyCJ7]

I have a 1985 CJ7 with a 258. Much of the engine wiring has been modified from stock and I'm trying to remove the hacked-on aftermarket stuff and get the factory gauges working again. I'm trying to figure out exactly how I should be setting up the factory water temp gauge.

What does the factory setup for the water temp sender look like? Specifically:

- What port in the intake manifold (or other location) does the sender use?
- What type of sender is factory? How many wires? Part number?
- How is it wired? Does it take 12v switched and send the signal to the gauge?
- Which wire is which? I have a hacked-apart painless wiring harness and no good way to figure out what wire goes where other than manual tracing. I have identified what I think is the wire that goes to the factory water temp gauge but I'm not sure what the rest of it should look like under the hood. I'd hate to buy a sensor and pigtail and then learn that it's an aftermarket part that doesn't work well (or at all) with the factory gauges.

Thanks! The more detail the better. Bonus points for pictures.

 

[gert]

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[gert]

Its 12 volts to the gauge, the 1 wire to the sending unit provides the variable ground to the circuit based on temperature which causes the needle to move

I dont remember where the sending unit goes other than somewhere around the pump and thermostat


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[TSB8C]

As gert said, that's the senor and it has a single wire from the temp gauge in the dash via the bulkhead connector on the firewall. Here's a shot of the bulkhead connector showing which pin that wire comes from. It is a purple or violet wire with a black stripe or tracer on it (left side mid-way down in this pic). There is another purple wire with no stripe that goes to the oil pressure sensor, so don't confuse them.



On the 258 I6 engine (after about '80 or so), the temp sensor is mounted up front in/near the thermostat housing.