Austin375

I got a 95 XJ with a 4.0 a few weeks ago. I knew there were issues so I expected work. Just replaced all the pistons, head gasket, oil pan gasket, new sparks, new water pump, new thermostat, and lost of littlecramp. My damn thermo gauge still doesnt want to budge. I'm not a mechanic, with the help of youtube I can do it and with my buddy who is an actual mechanic lol. But any thought on why she ain't working? I'm gonna replace the fuse tomorrow. But would like some thoughts and or comments

robertj

It's either the gauge or the sending unit. It's easy enough to test the sending unit (the sensor near the firewall on top of the head) with a multi-meter. Doubt you'll have any luck with the fuse, and if it is the fuse there's a reason it's blowing.

Austin375

We put a new sending unit in it already.

gat

There is a sending unit in the thermostat housing which controls everything else but the gauge in the dash. The gauge in the dash is controlled by the sending unit in the rear of the block.

downs

It's in the head not the block. Drivers side (same side as all the injectors) most of the way back. It's fairly small and goes straight down into the head. Could be as simple as the connector got knocked off. But if it needs to be replaced it's pretty easy and cheap even if you get the part from the Jeep dealer. Side not make sure your engine is cool before removing it. It goes into the head's cooling passages so is pressurized when the coolant is hot.

Dave51

(1) Turn ignition switch to ON. Disconnect coolant temperature sending unit connector. The gauge needle should move to low end of gauge scale. If OK, go to next step. If not OK, go to step 3
(2) Install a jumper wire from sending unit wiring to ground. The gauge needle should move to high end of gauge scale. If OK, replace sending unit. If not OK, remove jumper wire and go to next step.
(3) Turn ignition switch to OFF. Disconnect battery negative cable. Remove instrument cluster bezel and cluster assembly. Disconnect gauge cluster connector A.
(4) Probe cavity A1 of cluster connector A. Check for continuity to a good ground. There should be no continuity. If OK, go to next step. If not OK, repair short in circuit as required.
(5) Still probing cavity A1 of cluster connector A, check for continuity to sending unit wiring connector. There should be continuity. If OK, replace gauge. If not OK, repair open in circuit as required.

Dave51

Could also test sensor. Stick (not submerge) sensor in ice and boiling water (not simultaneously). Measure ohms. Compare:

Austin375

Thanks brotha. I appreciate you breaking it down simple for me.