92 300TE Outside Temp Display and Idiot 4 Matic Dash Light
 

92 300TE 4Matic.

My outside temp display always shows between 130 and 146 degrees regardless of the real outside temperature. Additionally if the headlights are turned on this display goes completely blank.

Would this be the temperature sensor or the display? How should one test these to determine the culprit?

I have noticed for quite some time that when starting this vehicle the 4Matic dummy Instrument Cluster light does not come on. The other day I removed the Instrument Cluster and replaced the burned out bulb. Now when ever the car is started this light remains on. I have gone to the engine compartment and switched the 4Matic test switch between test and engaged. Regardless the Instrument Cluster idiot light remains on.

Any clues as to begin diagnosis for this challenge?



Dave H...