What model is your van? I wasn't aware there is a reverse warning module/horn. Is that an option, and is that white/blue wire there even if the option is not installed?I use the white wire with thin blue line. That's the wire(+) for the reverse warning module/horn. It is located on the driver side at the pillar or under the dash board. Hopefully that helps.
No, it does not. That is the power to the backup lights.My backup warning horn beeper has a feature that it will operate in half volume (loudness) if you put it in reverse twice in short succession. I wonder if the white wire with blue line drops the voltage to make that happen?
Looks like I'm learning something the hard way again. Sorry about the mistake.As for the backup horn/beeper being available in NA as an OEM item......
My owners manual tells about the double shift into "R" will drop the volume, and my beeper has OEM wiring. Running the VIN number at the website that shows the build of the van ( https://carinfo.kiev.ua/cars/vin/mercedes/vin_check ) shows "JW0 - BACKUP WARNING SYSTEM" as a factory installed feature on my VIN.
Agreed! It may just need a DC logic high signal (usually .6vdc or higher) to trigger.However, for purposes of attaching a trigger for a backup camera, I doubt that the exact voltage on the signal line is all that important. As long as its significantly different from ground, I suspect any voltage is fine.
I'll give that a try, mine seems to be ridiculously loud!My backup warning horn beeper has a feature that it will operate in half volume (loudness) if you put it in reverse twice in short succession. I wonder if the white wire with blue line drops the voltage to make that happen? If it does, then that wire might not always have full voltage on it when using that feature.
I've read where folks use a connection at the gear shifter for a reverse signal.