Trailer Lights / CAN Bus system

[WALSHIE]

2014 Mazda CX-9, I installed genuine Mazda tow light package, plugs into harness, add fuse at main block, clean install.

Replacing trailer lights, hooked up right only. Running light worked, flasher worked. When on together, the running lights cause the car's running lights to go out. Turn off then on and they reset, lights work again for about 10 seconds.

I called superbrightLEDs and they say it most likely is the CAN Bus sysem in car.

Does anyone have experience with CAN Bus?

My thoughts:
1) I only had one light installed not two
2) Auto computer is expecting incandescent
3) Need to reset computer by pulling battery cable?

 

[pocket change]

Sounds like a bad ground.

 

[LouC]

My 07 Jeep has CAN Bus and when my trailer ground was a little corroded none of the lights worked till I stepped on the brakes and then somehow it grounded. I took apart an extension connecter in the trailer tongue and cleaned the terminals and it worked fine after that.

Take a multi meter and set it on continuity (it beeps when you have continuity). Take one of the probes and put it in the trailer connector for the ground (white wire) and the other probe touch it to the tongue or anywhere on the trailer frame. If you don't get a beep the ground is not making contact. If you really want to be thorough run a longer wire back from the probe you touched to the frame, to the mount for every light on the trailer. You should have continuity from the white wire in the trailer harness, at every light housing. On thing I did a few years back that helped was run a jumper ground wire from each side of the tongue, to each leg of the frame. Then from the rear leg of the frame to the rear light housings that were bolted to a separate piece of galvanized steel that was not making good contact with the main frame rails. The best way is to run separate grounds to each light housing but my lazy way is the much better than what most trailer companies do. Any connections where they can be un-plugged like an extension harness should be packed with dielectric grease to keep out moisture.

 

[WALSHIE]

Reporting back - no longer an issue. I was testing with one light, not two. When I went ahead and buttoned up all wiring on the trailer, installed all lights, etc, the issue went away. I underestimated just how smart the CAN Bus system is. It must have detected there was only one rear trailer light.