I have a '90 300e 4matic that the idiot light on the lower right of the dash coming on. The 4matic does not work. A some-what knowledgeable mechanic seems to think it is a relay or sensor. The pump was replaced 3 years ago. I'm at 227k miles.

The prognosis of a relay or sensor reasonable? What can I expect to pay for this?

Thanks in advance for your response.

 

I have one of these problem cars. I pulled the under the hood disconnect years ago. The car gets great traction without the 4matic. There is very little published on the system and fewer people who know anything. I plan to look into the 4matic in detail after I get thru redoing the head gasket and valves guides.
Never found any help at the local dealer for 4matic issues. I am looking for any manuals or info on 4matic, myself. After 15 years of looking haven't turned up anything.
Good luck.

 

4matic systems are expensive to fix ,even by Mercedes standards.
These will give you an idea what you are dealing with...