While driving yesterday, my temp gauge went all the way down to 40 (Canadian eh!) and stayed there for 1 hour. I was stuck in rush hour traffic, it would sometimes go back up halfway to just under 100 and then back down to 40. All other gauges working properly.

Reading online, I found that there are two temp sending units on my jeep with the 4.0 l. One in the front, and there's supposed to be one in the back at the rear of the block. I could only find a bolt with a grounding strap going to the firewall.

Please help

J

 

I take it that this is a 2000 Cherokee XJ body.


There is only one Engine Coolant Temperature (ECT) sensor - that is mounted on the thermostat housing. No others.


Examine the electrical connector on the temp sensor for loose wires. Unplug the connector and see if the pin cavities in the connector are corroded or the pins in the ECT are corroded.


Operate the engine up to operating temp. Have a helper watch the temp gauge while you wiggle the wires going to the ECT and at the wire loom exiting the end of the plastic wire manifold on the left side of the rocker cover. See if the temp gauge reading jumps around.


Do you have a CHECK ENGINE light (or engine graphic) on. Normally any disruption in the ECT circuit would trigger a Diagnostic Trouble Code. If you can, see if you can use a code reader or scanner to see if there is a DTC or pending DTC.