Addition reversing lamps

[Bandos]

OK so at the weekend I decided to connect up some additional LED reversing lights. First I removed the rear light cluster, I then soldered a wire the live feed to the reversing light in the cluster and connected the negative on the new lights to a ground point. Selected reverse gear, turn on the ignition (but not start the engine) and the new lights illuminated for 5 seconds then both the new and the existing reversing lights went out! So I turned the ignition off.

After I disconnected the new lights, (Selected reverse gear, turn on the ignition) the existing ones resumed service. So whats happening?

Attached is the connector wiring schematic. I have not yet investigated which colour feed which light. Thats next on the list. The green circles are blanking plugs.

Interesting side fact. I have rear fog light switch on the dash, which illuminates when switched on with the dip beam lights. But there is no light fitting installed in either of the rear light clusters for the rear fog lamps!

This is on a 2013 Boxer PVC

 

[meanders]

I suspect the LED wired in parallel (The only way of doing it) changes the load (resistance) such that the CANBUS drops the power as it detects too much is being drawn and therefore it must be a fault.

 

[Clivefog]

No rear fog light how do you get an MoT?

 

[Two on Tour]

When I fitted additional LED reversing lights, their wattage was 20 watts for the two, so I just removed the existing 21 watt reversing lamp bulb and the CanBus system was happy with that.

 

[Bandos]

No rear fog light how do you get an MoT?

Very good question! Never been asked about rear fog lights at the MOT station.
I think they are the Fog light is mounted lower down below the main light cluster in the grey bumper area.

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[Bandos]

I'm thinking I will have to switch the additional reversing lights from their own feed

 

[pappajohn]

You could use a cheap canbus relay as used on towbar wiring.
You only need the trigger wire connected to the main wiring, which is very low powered, and a live feed to the relay from somewhere which isn't canbus related.
The fog lights will then be powered from their own supply via the relay and switched by the trigger wire from the original lamp wiring

 

[Bandos]

Great idea, any links to something suitable?

 

[pappajohn]

Great idea, any links to something suitable?

Something like this.
Very easy to wire.

https://www.amazon.co.uk/dp/B098KDFFHR?tag=mhf04-21

 

[Bandos]

cheers for this

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[davejen]

The rear fog light should be in the R/H lamp, your pic shows the left, have you checked the other?
Cheers, Dave

 

[Guzziando]

On a similar issue, I decided to fit some LED bulbs to replace the existing 16W reversing light bulbs on my Fiat Ducato, to produce more light when reversing in dark places. They stated that they were CANBUS compatable, but are throwing up a CANBUS error on the dash. When I measure the resisitance of the bulb compared to the LED bulb, the LED has more resisitance. Any thoughts on how I can overcome this? I did think about load resistors, but I am assuming that would increase the resisitance further?

 

[Guzziando]

Ignore the above post, I had a couple of 25W Load Resistors spare from when I fitted LED indicators to my motorbike. Wired them across the live and earth, the warning sign has gone, and the lights are nice and bright. Just got to locate the resistors where they will not do any damage due to heat.

 

[optimus-prime]

I'm thinking I will have to switch the additional reversing lights from their own feed

That’s what I did. But I did it because I thought I may need them also while driving forward, because of the overhang. Also thought I may need them when parked, for whatever reason.