LIbeach4x4

(1998 Grand Cherokee Limited 4.0L) Okay, so I've been trying to figure out why my temperature gauge always reads MAX High and causing my CHECK GAUGES light to flash all the time (even when cold engine)? I have tried changing out my Coolant temperature sensor to no avail. I also noticed when my coolant sensor was disconnected the temperature gauge still reads MAX HIGH. I was recommended to replace my temperature sender (different sensor) However since my vehicle is equipped with a 1998 engine I do not have this sensor and apparently the coolant sensor I do have performs both functions. Also after warming up the Jeep when I shut the key off and turn the key back to Auxiliary the gauge appears to read accurately for like 2 seconds and then when all the dash lights flick off the gauge immediately cranks over to MAX high and the Check Gauges Light comes on. So my question is does anyone know where this problem may be hiding? Could it be the gauge itself or the ECM? What could I try next? -Thanks any advice would be greatly appreciated!

dave1123

Sounds like the wire to the sensor is grounded somewhere. If you disconnect the plug at the sensor, the guage should read dead cold.

LIbeach4x4

Attempted to find any evidence of the wires grounding out could not find anything yet. I thought if i disconnected the the plugs to the ECU I could Isolate the ECU as a possible cause, even with the ECU disconnected the temperature gauge still spikes to max high when you turn the key to auxiliary. Could this mean the cluster may be bad?

dave1123

Could be the guage is shorted in the cluster. It shouldn't be live on aux. Only the radio, wipers, and cigarette lighter are hot on aux. Did someone install an after-market radio or amplifier? They may have accidently done something to the guage wire.