Coolant gauge not working

I am trying to diagnose a non-working engine temperature gauge in a 96 Mustang 4.6L GT.
Currently the factory gauge in the cluster does not function at all.

There are two engine temperature sending units/ sensors on this generation of Mustang, on either side of the center mounted alternator in the lower plenum of the upper intake. From my understanding/ research; one of the senders is an ECT, sending data to the engine computer (driver side) and other is for the cluster gauge (passenger side). Both are two wire connector plugs and the connection plugs are the same. I am not sure that they are both the same sensor.

https://www.cjponyparts.com/coolant-...2004/p/HW1321/

When I unplug the passenger side sending unit/ sensor and ground the red w/ white line wire and turn the key to 12V acc the gauge maxes out, therefore confirming the gauge and wire are functioning fine. I have replaced the sensor, which did not solve the problem. I have tried an alternate ground for the switch (after the plug), tried bypassing the plug connector and wiring direct to the switch but have not been able to isolate the problem. I have also confirmed the engine has adequate coolant ensuring that the sensor is able to detect the temperature fluctuation.

At this point, based on everything I have tested, the only thing I can come up with is that it is not the same sensor/ sending unit used for both sides of the plenum. Does anyone else have any other suggestions on how to resolve the issue?

Did you confirm you were sold the correct sensor for the gauge vs ECM?
Another situation where I'd go OEM Ford only, nothing but trouble from aftermarket versions.

I can only confirm the sensor I bought is the same as the one I replaced it with. Have no idea if it was the correct sensor in the first place. Plug suits the sensor, so it appears to be correct, but I feel that I have diagnosed everything on either side of the sensor to be able to isolate that it is the issue


Ford was a 2 week backorder, so bought aftermarket unfortunately

Due to issues, we've flat out stopped using aftermarket ones.

OEM sensor solved the problem. Gauge is functioning as it should be

OEM sensor solved the problem. Gauge is functioning as it should be.

Thanks for the recommendation Rick!

Good to hear it was just that easy.