Hey

I have a 626 from 1989, I've had it for three years and until now I've had no electric troubles. Yesterday, I helped my friend move and therefore towed a trailer.

Now, just for reference, I've towed many times without fault, last time (before this one) was a month ago. Never had any issues.

However, this time, I plugged in the cable (it was a 13-pin from the trailer, 13 -> 7-pin adapter, and then into the car. All the lights on the trailer seemed to work. I sat down in the car, and drove off. Immediately I noticed that the right blinker light (the arrow) on the instrument panel was dimly lit. I tried blinking right to see if it was stuck; the blinking started (with a more powerful light than when not blinking) and stopped when I put the lever into the normal position. The dim light was constant. Also, when blinking right, both of the trailers blinkers turned out, when blinking left, nothing happened.

In hindsight, I shouldn't have been so lazy as to write it off as nothing, as roughly 15 minutes later the dim light turned off - and the relay showing that one of the lights is out turned on. I stopped at the side of the road, as I was unsure which light was not working, as the red light on the instrument panel only indicates that one of the lights is non-functional. I checked the bulbs in the rear lights and one on each side was broken (turned out it was the rear positional lights). I went to the store and switched them out, but nothing happened, they wouldn't turn on.

I checked all other exterior bulbs, they were fine (and working). On the rear lights, the fog lights work, the brake lights work, (can't remember if the reversing white light was working), but not the positional lights. I've checked the bulbs with a multimeter to see if they both(!) were perhaps broken in manufacturing - but they worked fine.

Now none of the lights on the trailer work through the cable. Blinking that previously turned on both blinkers on the trailers now turn on none.

I'm thinking that the adapter was the culprit here, though I'm unsure on how to continue the troubleshooting. What would the next step be now? I've looked at the actual connector on the car and it doesn't look that rusty or bad (see attacehed picture). Could it be the relay? I'm also considering a short because of the fact that blinking right would blink both sides of the trailer, while blinking left did nothing.

Thanks, Christian