Hi, on my 94 4.0 4x4 I have no readout on the temp gauge when at operating temp. Grounding the temp sensor reads full cold on the gauge while grounding the gauge wire reads full hot. Would that indicate a faulty sensor? Thanks.

 

Sorry about the double thread. Still getting used to the forum layout.

 

There are two temp detection units on fuel injected engines
ECT sensor, 5volt, always 2 wire, only used by the computer
Temp Sender, 12volt, 1 or 2 wire, only used by dash board temp gauge
So NOT the same, or interchangeable

Temp Sender will have a red/white wire that runs to the dash gauge, if you ground that wire and turn on the key the gauge should go to full HOT, if so wire and gauge are OK
1 wire Sender uses its threads as the ground to engine, so lower threads must be bare metal for a good ground
2 wire Sender will have an added Black/white wire, which is the Ground, these were used when more plastic parts were being used and "engine ground" was less certain, lol

ECT sensor uses a green/red wire and grey/red wire

These two units look the same, but are not the same internally

1994 should have 1 wire Temp Sender, red/white wire
On a 1994 4.0l the ECT sensor and Temp Sender are located next to each other on lower intake above thermostat housing

 

Thanks. I was referring to the sender. If I understand correctly that means the gauge and wire is fine. How would I test the sender aside from measuring resistance?

 

You don't test it you just replace it, if wire and gauge test as OK

But you can test it with an OHM Meter if you want, chart here: https://www.vintage-mustang.com/atta...14-png.761171/

But when you test it you will most likely find it has N/C(no connection) or HIGH OHMs which don't change when sender is heated

 

Thank you very much. Your vast automotive knowledge is astounding!