4Matic question

[brooktre]

I have a 91 300E 4Matic with 82k miles. The 4Matic indicator light (the one that tells you that you are in 4wd) comes on intermittently. There does not seem to be a pattern as to when this occurs. It it happens at different speeds, temps etc. The 4Matic problem light (on the bottom of the display) does not come (unless you disable 4Matic with the switch under the hood). This car is new to me and so far I have only driven it on dry roads at normal speeds, so I don't think that the 4wd should be engaging. I checked the tires and they are Pirelli P6000 (195/65R15 - N1) with about 60% tread. These are the correct size according to the owners manual. My independent MB mechanic checked for trouble codes and found none. My guess is that I have a sensor that is malfunctioning, but I'm not really sure where to start. Any help will be appreciated.

Todd

[Lebenz]

The wheel sensors are a good place to start. FWIW, my former 4-matic would engage briefly if the car did something as simple as a quick left or right turn.

[mbdoc]

The yellow triangle comes on any time that the car starts to lose traction!
IF the tires aren't exactly the same circumference then the light can come on at any time.

[ranger]

Sometimes the 4-matic light comes on in mine, when driving over rough surfaces, under acceleration and hit a bump, or when it's a little wet and it shifts can sometimes cause the light to come on.

[brooktre]

Is there a way to test the wheel sensors?

I do believe that something is wrong, because the light is on about 75% of the time. Again, this occurs on dry straight roads at normal speeds. Sometimes going down the interstate it will come on and go off without changing lanes or doing anything abruptly.