I inherited an '87 420SEL with a corroded and seized antenna. I purchased a new antenna and am attempting to install it, however the motor appears to rotate in one direction only. It activates when the radio is switched off to draw the antenna down, but does not change direction to push the antenna up.

(I cannot seem to get the main gear to catch the antenna belt either, but that's a problem for later.)

Can someone explain the principle behind it's operation please? Do I have a defective antenna motor which needs replacement?

 

can you be more specific? if it will draw the antenna down then it means the antenna can also go up, otherwise how will you know it goes down if it is not up??????????????? You can get better help by providing a clear scenario of your problem

 

Let me try again...

I removed a seized antenna. I have a new antenna to replace it.

The instructions for replacement tell me to turn the radio on to eject the old antenna. The antenna was seized so this could not be done. I opened the cover and pulled it out manually.

With the radio still on I am directed to insert the nylon toothed belt of the new antenna into the antenna hole and push it down until it stops and engages the nylon gear wheel. At that point, if I turn the radio off, it is supposed to catch the nylon belt and draw the antenna down. The wheel will turn counter-clockwise for about 12 seconds.

My first problem is that I have been unsuccessful in getting the nylon toothed belt from the antenna to catch the gear wheel.

I'll keep trying, but all that aside, I notice that when I turn the radio back on to make a second attempt, the antenna motor does not turn in the opposite direction or at all, as one would expect (to raise an antenna). It only rotates counterclockwise when the radio is turned off (to draw it down).

So I am guessing that the antenna toothed belt must be taken in completely, whereupon it must trip a reversing switch or gear. I assume I will only see the gear wheel rotate in a clockwise direction (to raise an antenna) after I have achieved success it getting it to wind in first.

I have taken off the cover to observe the belt engagement but gave up after half a dozen attempts to get it to engage (it started raining heavily). The belt has a memory which twists the teeth away from the gear so it is very frustrating trying to get it to catch the gear. Each time I need a friend in the car to turn the radio on and then off to get the gear moving.

So...are my assumptions about a trip switch or cog to reverse the motor correct ? Will it turn clockwise once I actually manage to get the antenna to wind in, or do I actually need to replace the motor with one which will go in both directions when activated by the radio control ?