Trailer Lights repair debugging
My father had a trailer which worked quite well, until it didn’t. One of the lights were broken and on further inspection, it seemed that the wiring was completely weird from the beginning.
| should be lit | is lit |
|---|---|
| reverse gear light (right) | right license plate and rear light |
| break lights | left break light and reverse gear light on the right |
| rear light | left rear light works |
So this is quite twisted and has to change. The problem is either at the connector plug to the car - or at the wiring in the back. Somehow it is nearly impossible to open the connector plug without a lot of tinkering as can be seen in this video: https://youtu.be/a4VpIPYbngc
The opened trailer lights wiring
So I looked at the trailer wiring and tried to change the wires accordingly but found out that it is impossible to fix this only on this end. The license plate light and rear light has to stay together and as this is the only cable with two wires, I would have a hard time of rewiring those.
After more than one hour into this problem I found out that the final solution was not to adjust the whole wiring, but the plug from the front to the wire which goes into the tail lights which can be seen here:
The final solution was to unplug this plug on the back of the light - turn it one pin further - and voilà
This plug contains a ground pin in the middle and four other pins around it, as can be seen in the picture of this trailer light kit. The solution was finally, to just turn this plug around one pin, so that the normal rear light position is at the expected position (thats the easiest to check).
Example picture of a trailer light kit
After 1.5 hours we have solved this problem, which felt a lot like debugging computer systems, was not fun at all but had a fulfilling moment at the end when the problem was fixed.