Hi,
I just installed an aftermarket amp and it often outputs a 40-60Hz tone, typically when car is unlocked but ignition not on, or after car is locked, or when the audio test is run (such as when 5F is scanned during a VCDS scan). It happens often but not always, but when it's stuck transmitting the tone switching on some audio/music won't get it to stop. However if I start the car and turn on the radio and it hasn't gotten stuck humming, the output is clean (only transmits signal from music, tone is gone).
Details:
Amp: Alpine KTA-200m, +12v from spare fuse in fusebox, grounded to the pass side trunk ground stud (also tried grounding to rear seatbelt bolt, tone was exactly the same). Do I need to ground it to the same grounding point that the MIB uses? Most people running aftermarket amps just bolt it to the chassis near the amp, haven't seen anyone needing to do this.
Input: rear parcel shelf subwoofer (original sub is unplugged). I've tried measuring the amp signal in for the signs of the tone but haven't been able to see it there, maybe too weak for my voltmeter.
+12V Trigger: power wire going to rear camera module, seems to switch on with MIB.
Low-pass set to default 120Hz, gain to middle.
Any ideas? My only other piece of aftermarket wiring is an RS3 LPFP + controller which is grounded near the rear seats, any way that's causing a ground loop?
I just installed an aftermarket amp and it often outputs a 40-60Hz tone, typically when car is unlocked but ignition not on, or after car is locked, or when the audio test is run (such as when 5F is scanned during a VCDS scan). It happens often but not always, but when it's stuck transmitting the tone switching on some audio/music won't get it to stop. However if I start the car and turn on the radio and it hasn't gotten stuck humming, the output is clean (only transmits signal from music, tone is gone).
Details:
Amp: Alpine KTA-200m, +12v from spare fuse in fusebox, grounded to the pass side trunk ground stud (also tried grounding to rear seatbelt bolt, tone was exactly the same). Do I need to ground it to the same grounding point that the MIB uses? Most people running aftermarket amps just bolt it to the chassis near the amp, haven't seen anyone needing to do this.
Input: rear parcel shelf subwoofer (original sub is unplugged). I've tried measuring the amp signal in for the signs of the tone but haven't been able to see it there, maybe too weak for my voltmeter.
+12V Trigger: power wire going to rear camera module, seems to switch on with MIB.
Low-pass set to default 120Hz, gain to middle.
Any ideas? My only other piece of aftermarket wiring is an RS3 LPFP + controller which is grounded near the rear seats, any way that's causing a ground loop?
