1991 300 TE 4Matic, great car with 200,000 miles, 4matic light on dash just lit up and it wont engage 4 wheel drive. Found hydraulic reservoir was low and added correct MBZ fluid, light flickers when engine starts then goes on full time, 4 wheel drive will not engage. Here in Sun Valley, Idaho , we have a lot of snow and I have driven over big ridges that may have rubbed the undercarriage, can't see any damage. I build Bonneville race cars and powerful engines but I don't have a clue about what to check on this car to fix the electronic computer controlled 4 wheel drive.
Can any body give me some ideas. I called the dealer's service writer and he told me to add hydraulic fluid to the coolant overflow reservoir???
Thanks to all.