MK7 universal bypass relay - trailer lights

[jimstef]

I wish to wire my lights to an rear light bar (5 core trailer wiring, LED). Any recommendations on a universal bypass relay that will work with my 2015 golf. I'm seeing prices from $600 to$65 for universal bypass relay modules. They all look like they could do the job but I'd like to know if there is a confirmed product that would meet my need. Thanks

[DV52]

@jimstef: Hi. I've not installed a universal bypass relay to a mk7, but native module that controls the car's 35 x exterior lights is a CAN based unit (it's called the Body Control Module, or BCM). I assume that ALL modern bypass relays are compatible with CAN based control modules because the protocol is an industry standard.

There's nothing particularly special about the mk7 BCM; for the tail-light function, it provides power to each light using Pulse Width Modulation for dimming (which is also industry standard these days). So make sure that the bypass relay will accept PWM. The other aspect of the CAN based BCM on a mk7 is that it also monitors the state of each lamp in the tail light fittings for faults (like short circuit and open circuit). It's important therefore that the bypass relay doesn't produce any fault-like signal back into the BCM - which is unlikely, but worth confirming with the manufacturer!!

Why do you want to fit a light-bar to the rear of the car?

Don

[jimstef]

Thanks Don - I'm using a bike rack over the rear hatch and have duplicated the rear tail lights.

Thanks again for the input.

Jim