Hello

I have a 1987 300TE 4matic (euro) same as 1990 with rebuilt transfer case...up to a couple weeks ago everything was working fine.

Now the 4matic warning light starts flashing whenever the AWD tries to engage I.E. when the car is standing still or below 16MPH or in slippery conditions. The problem is that the 4matic does not engage for some reason.

If I let the car running on park for a few minutes, the 4matic warning light will eventually stay on until I disconnect the battery and restart the car. Also I tried to get codes when the light is on from shorting pin 5 and 1 of the x92 connector but I can't get any codes.

Thing I have checked.

1) hydraulic fluid level is good
2) tandem pump is working fine
3) the transfer case is not leaking and the ATF level is fine
4) there is no leak in the hydraulic lines
5) hydraulic fluid is circulating in the system as I can see fluid coming out of the return line at the reservoir


What could be causing my problem ?
My mb mechanic doesn't know what to do

thanks

Nicolas