Hello, I have an 83 300 SD with a temperature gage that seems to be malfunctioning. The gage will jump from 80C to 85C suddenly. Sometimes it will drop from 100C to 85 C suddenly. This seems to happen more if the A/C is switched on and off.

Has anyone else had anything like this? Shouldn't the temp gage make smooth transiitions?
I've checked the instr. panel for loose screws. No ground wires appear to be loose. Sensor was replaced 4-5 years ago with an aftermarket replacement.

Is this a grounding problem?

It could be a grounding problem, but usually it is a faulty gauge if nothing else has fixed it.

------------------
Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Well, I actually ended up replacing the cluster with a new one.

It solved the car's "overheating" problem, the temperature is now in the normal range.

However, there still is a little bit of jumping in the indicator, esp with A/C switched on and off rapidly.

Might my aftermarket Car alarm have something to do with this? Or a defective temp sender?