The Hirschmann automatic antenna on my 97 S420 stopped retracting a couple of months back and recently broke off. Ordered a replacement Hirschmann antenna mast and cable which came with instructions on how to replace. Problem is that antenna motor runs only when the radio is turned on and does nothing when the radio is turned off. Is the antenna motor not a reversing DC motor which runs in one direction when the radio is turned on and in the opposite direction when it is turned off? Any suggestions on how to analyze and/or repair?

 

you have to first make sure that the old antenna is not broken off inside the motor. compare the old one with the new one and check the length of the cable. if its not broken then turn on the radio and then get the antenna ready. youll have to remove the old chrome screw that holds in the antenna. turn off the radio then push the antenna down into the hole......im not sure which direction the teeth go...usuallly facing the rear of the car . but you can try either forward or rearward.
then it will pull the anteena into the motor.