74 Oil Temp Sender & Gauge

[7pcars]

My gauge needle moves slightly when the ignition is turned on but no longer moves when the engine warms up. Any thoughts is the sending unit dead or a wiring issue?

[tonythetarga]

Could be either, but the sending units are known failure points. 5 or 6 bucks to replace is a good place to start.

[bdstone914]

Ground the wire at the sender. It should peg the gauge. Test the resistance of the sender cold then warm it with a heat gun and it should decrease in resistance. The wire from the sender to the harness is a green wire that connects into the main harness on the passenger side.It could be unplugged. Most problems are in the wiring. You can also ground the G wire on the back of the gauge and it should also peg the gauge.

[bdstone914]

Originally Posted by tonythetarga

Could be either, but the sending units are known failure points. 5 or 6 bucks to replace is a good place to start.

You may be thinking of the low pressure switch. The temp senders are not cheap and require draining the oil to change.

[tonythetarga]

Originally Posted by bdstone914

You may be thinking of the low pressure switch. The temp senders are not cheap and require draining the oil to change.

Thanks. I believe you are correct. You also may have answered my question in another thread on finding out what the green wire was coming off the rear harness in the engine bay. Dave also suggested it could be oil temp wire. My car doesn’t have a center console or gauge so I think I’ll just protect the bare end and call it good.
Thanks