Adding Driving lights to a car with CANbus?

[MC Bodge]

To add a set of auxiliary driving lights, I'd ordinarily just fit a relay in the main beam circuit to switch a supply from the battery for the new lights.

I'm intending to try it, but is this likely to cause a problem on a car with Canbus (Mk4 Mondeo)? Will the relay in parallel with the bulb cause a "main beam bulb fault" or disabling of the circuit?

[ch427]

i dont think the coil resistance would affect it but cant say for sure

[marksbike]

You should be ok if you do it at the headlight and not at the light switch. The light unit will have normal wires carrying the load for the bulb. Wires at the light switch/module will go to a BCM type module via canbus to be distributed around the car.

I've fitted spot lights onto the new minis and switched a relay by connecting to the highbeam wire at the headlight.

[MC Bodge]

marksbike said:

You should be ok if you do it at the headlight and not at the light switch. The light unit will have normal wires carrying the load for the bulb. Wires at the light switch/module will go to a BCM type module via canbus to be distributed around the car.

I've fitted spot lights onto the new minis and switched a relay by connecting to the highbeam wire at the headlight.

Cheers. I'd hoped that was the case.

I found the high beam cable and I've started the wiring, just need to finish it at some point.

[MC Bodge]

Now installed, wired-up and working, with no obvious problems.

Cheers.

[marksbike]

Result!