I bought my 2016 2500 with a Pioneer radio/nav unit installed. The unit works fine and is patched in through what I think is an after-market harness. However, FM has been poor. Didn't take much research to find out that many after-market harnesses do not supply power to the Sprinter's antenna amp located in the antenna housing. So, I tackled the problem by removing the stereo and the dome light giving access to the bottom of the antenna.
From the antenna a violet/black wire is supposedly the power wire, a black wire carries RF signal and neutral is through the body.
I established continuity between the violet/black wire at the antenna and a violet/black wire into the harness which has no connection to anything else (in the stereo).
So, I say "bingo" and all I have to do is patch into the violet/black wire and feed it a voltage from the stereo's blue/white wire which is a trigger voltage for electric antennas or power amps to turn on.
But, I try to be careful and so before patching into the violet/black wire I want to verify that it doesn't get 12V from somewhere else under the dash. So, I probe it with the stereo on and I see what? I see -12V. Minus twelve volts! Polarity on my meter is correct. Where does -12V come from???
My theory now is that the unpowered antenna amp itself somehow magically puts out -12V through induction voodoo. Can anyone who knows anything about RF amps comment on that? Besides that theory is there a Canbus -12V signal?
Obviously I don't want to connect +12V to something that appears to be at -12V unless this is a stray signal from the unpowered antenna amp. Thanks for any feedback.
From the antenna a violet/black wire is supposedly the power wire, a black wire carries RF signal and neutral is through the body.
I established continuity between the violet/black wire at the antenna and a violet/black wire into the harness which has no connection to anything else (in the stereo).
So, I say "bingo" and all I have to do is patch into the violet/black wire and feed it a voltage from the stereo's blue/white wire which is a trigger voltage for electric antennas or power amps to turn on.
But, I try to be careful and so before patching into the violet/black wire I want to verify that it doesn't get 12V from somewhere else under the dash. So, I probe it with the stereo on and I see what? I see -12V. Minus twelve volts! Polarity on my meter is correct. Where does -12V come from???
My theory now is that the unpowered antenna amp itself somehow magically puts out -12V through induction voodoo. Can anyone who knows anything about RF amps comment on that? Besides that theory is there a Canbus -12V signal?
Obviously I don't want to connect +12V to something that appears to be at -12V unless this is a stray signal from the unpowered antenna amp. Thanks for any feedback.