Originally Posted by eagsc7
Sounds to me like you've broke the ceramic in the sensor. I'd almost bet that your CEL is on. This sensor sends the temp to the computer for various reasons. I'd get it replaced when you can.
Yeah... your temp gauge would still work. The sensor for that one is by the firewall. It's behind the #6 cylinder on the Drivers side. Has either 1 or two wires attached to it.
Hmm... Believe on the OBDII 4.0 engines, 96 and up, there is only one engine coolant temp sensor on the thermostat housing. And this is where the temp gauge receives receives the coolant temp signal passed through the PCM.
So your 94 would have 2 coolant sensors where the rear one would supply info to the temp gauge. But on the original poster's 97 4.0 there would only be one engine coolant temp sensor like on my 96. Someone can correct me if I'm wrong but there's no mention of 2 coolant temp sensors in the 96 FSM.
Agree, the temp sensor on the T-stat housing should be replaced if there's a CEL on and they're aren't very expensive. Teflon tape and/or gasket sealer/maker is a good idea on the threads if replaced to prevent leaks.