JMSimard36

Just wondering what everyone thinks! I have a 98 cherokee classic an my gas gauge reads half at all times, I unhooked the harness going to the fuel pump and filled it with grease and no change, so is it the sending unit or the dash unit?

ZINGGG

You can always pull the dash and check for corrosion at the plugs. But my guess would be a faulty fuel level sending unit. It's part of the fuel pump assembly and would need to be replaced as a whole

Rustydog555

Unplugged should read empty
Ground the wire to gauge should read full
I could have that backwards
but if the gauge doesn't respond could still be wiring but likely gauge

Cherockee

How long has it been like this? Was it a gradual thing or did it happen all of a sudden?
Mine was stuck on empty. When I pulled the fuel pump I found the contacts for the level sender were corroded away, aparently from there being water in the tank for some time. Put a new one in and it still doesn't read correctly. Still haven't fixed it yet though.

CCKen

To isolate the fuel gauge from the rest of the circuit, perform this instrument cluster actuator test. If the fuel gauge responds to the test it shows that the CCD Data Bus is working between the PCM and the cluster and the gauge itself is okay. If not, and all other gauges work properly, suspect that the gauge is faulty.

Instrument Cluster Actuator Test

(1) Begin the test with the ignition switch in the Off position.

(2) Depress the trip odometer reset button.

(3) While holding the trip odometer reset button depressed, turn the ignition switch to the On position, but do not start the engine.

(4) Release the trip odometer reset button.

(5) The gauges should cycle through their ranges, stopping at intermediate readings, going up and going down, at two second intervals. The indicator lamps should cycle on and off.

(6) The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test, if the ignition switch is turned to the Off position during the test, or if a vehicle speed message indicating that the vehicle is moving is received from the PCM on the CCD data bus during the test.

JMSimard36

Ok so I did this and the fuel gauge and the battery gauge never moved like the others, what does this mean?

CCKen

It looks as though the problem is in the instrument cluster itself. Here's what the FSM has to say about the actuator test:

The instrument cluster actuator test will put the instrument cluster into its self-diagnostic mode. In this mode the instrument cluster can perform a selfdiagnostic test that will confirm that the instrument cluster circuitry, the gauges, and the CCD data bus message controlled indicator lamps are capable of operating as designed. During the actuator test the instrument cluster circuitry will position each of the gauge needles at various specified calibration points, and turn all of the CCD data bus message-controlled lamps on and off at specified time intervals. Successful completion of the actuator test will confirm that the instrument cluster is operational.

If an individual gauge does not respond properly, or does not respond at all during the actuator test, the instrument cluster should be removed. However, check that the gauge mounting screws on the instrument cluster electronic circuit board for proper tightness before considering instrument cluster replacement. If the gauge mounting screws check OK, replace the faulty cluster.

If the rest of the gauges respond correctly to the actuator test except these two gauges, changing the connector at the back of the instrument cluster, bending the connector pins for better contact, or packing the connector with dielectric grease will not help in this case.

Remove the instrument cluster and disassemble it to the extent where you can examine the gauge mounting screws and closely examine the electronic circuit board for cracks in the printed circuits.

FYI: I did find a thread on a Wrangler forum some time ago where a forum member repaired a broken printed circuit and fixed some instrument cluster problem he had.