1985 190E Power Antenna
03-24-2024, 12:35 PM
#1
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1985 190E 201 pre facelift, Ford F150, BMW Z3, 79MGB LE, 1934 MG PA
1985 190E Power Antenna
I have pulled the power antenna, and am trying to "bench test" it. I have a pretty good idea of the wiring positions, but have not been able to get it to work given the Utube post that I am using to diagnose the project. I am able to get it to go up and down if I go directly to the motor, in other words I take 12Vdc to the motor and it goes up, then switch the + and - and it goes down. So, could the circuit board be the problem? Any thoughts? Thanks,
randy
randy
03-24-2024, 03:02 PM
#2
Super Member
Most likely, yes your circuit is fried. I see this a lot because the system only has a current sensor. Basically when the antenna end point is reached the motor is stopped mechanically and naturally the current draw goes up by a lot. The board senses this and shuts off the motor within a second. If there is a malfunction and the current sensor fails the shut off will not happen and eventually the power transistors will overheat and get fried or more likely the board will fail.
Inspect the board closely for burn marks at the output stage to the motor.
The other possibility for a malfunction is that if you do not have your original radio/stereo, the replacement installation was botched.
Interestingly I had both problems all in one. Both the antenna board was fried and the stereo replacement was botched because the antenna was not working anyway so the installer had no way of checking if the installation was right. So I had to fix both problems.
Since your car is pre -89 you mush have an antenna switch on your dash.
You will have to find out how that circuit operates with that switch in play and bench test your antenna by not directly powering the motor but directly powering the entire unit. That is step one. Not sure if I captured/documented this. I may have some documents to share if I did but you can find the answers on the WEB as well.
I got that working on the bench first. After that I had to diagnose why it did not work in the car. It turned out the installer did not connect the radio on signal to the aftermarket head unit. Once I fixed that, antenna started working great! BTW the radio on signal did not even exist on the head unit, so I had to connect that signal to a 12V line. Which causes the antenna to go up and down every time the ignition is turned on and off. In a proper installation with this feature the antenna only goes up when the radio is active.
-Cheers!
Inspect the board closely for burn marks at the output stage to the motor.
The other possibility for a malfunction is that if you do not have your original radio/stereo, the replacement installation was botched.
Interestingly I had both problems all in one. Both the antenna board was fried and the stereo replacement was botched because the antenna was not working anyway so the installer had no way of checking if the installation was right. So I had to fix both problems.
Since your car is pre -89 you mush have an antenna switch on your dash.
You will have to find out how that circuit operates with that switch in play and bench test your antenna by not directly powering the motor but directly powering the entire unit. That is step one. Not sure if I captured/documented this. I may have some documents to share if I did but you can find the answers on the WEB as well.
I got that working on the bench first. After that I had to diagnose why it did not work in the car. It turned out the installer did not connect the radio on signal to the aftermarket head unit. Once I fixed that, antenna started working great! BTW the radio on signal did not even exist on the head unit, so I had to connect that signal to a 12V line. Which causes the antenna to go up and down every time the ignition is turned on and off. In a proper installation with this feature the antenna only goes up when the radio is active.
-Cheers!
Last edited by dolucasi; 03-24-2024 at 04:31 PM.
03-24-2024, 04:37 PM
#3
Super Member
In case you need it here is the pre-90 antenna wiring. If you do not have it you will need it for bench testing as well as installing in the car.
03-25-2024, 02:09 PM
#4
MBWorld Fanatic!
You might be able to source both a new radio and a new antenna from Becker Auto Sound which is the OEM. A few years ago, I needed to replace my antenna that had stopped working and that's where I found it.
