What happens when you assume?

[coy55boy]

Actually, the spelling should be ass_me because I can't say anyone else was made an ass of...

 

I bought a little trailer to pull behind my Wing. I thought it would be perfect since the Wing already had an unusual 6 wire weatherproof connector and the trailer was equipped with the same device.

 

I got the bike out and attached the trailer coupler to the hitch ball and was thrilled to see that the trailer tongue was perfectly level. Then I connected the chains and stood back to admire my work. So far, so good. Next, I connected the wire harness and turned the ignition key to on to verify the lights working properly on the trailer.

 

That's when all hell broke loose! As soon as I turned around, I could see dense white smoke billowing out from the under the trunk. I immediately turned the key off and went to assess the damage. When I got to the back of the bike, I could see that the rear lights were still on. HUH? I already turned off the key... I figured (assumed) that somehow the rear lights were getting feedback voltage from the trailer, so I disconnected the wire harness. Nope, still got lights. So, I thought maybe I should start the bike to possibly reset any relays that had gotten stuck. It started right up, but I'm still getting smoke. By now, I'm beginning to panic. After turning the key to off, I quickly yanked the side cover off and pulled the main fuse. But, even that didn't stop the smoke! Now that the battery is exposed, I ran back to the garage for a wrench and disconnected the battery. Finally, the smoking ceases.

 

It seemed like a long time, but this all took place in about 2 or 3 minutes. I opened the trunk but realized that there could be nothing in there causing the problem. I opened the left bag. This is where the previous owner installed 2 additional fuse boxes (for the lighting, audio system, trailer, etc.). I checked everything over and couldn't find any visible indication of extreme heat or any wires hot to the touch. Next step is to remove the rear fender and start following the wire harness. As soon as I got the fender off, I could see the culprit.

 

A trailer wiring harness isolator had been installed. It was now a tortured, twisted mass of plastic, wires, and epoxy. After doing some research online, I could find no 'standard' wiring setup for the harness connector. So, the assumption I made (that made an ass of me) was that they would already be correct. Compounding the issue was that whoever installed the isolator (gotta blame someone!) had put in a 30 amp fuse. The online instructions said 10 amp max. The auxiliary fuse box was wired directly to the battery which is why pulling the main fuse didn't help. The likely culprit for all the mayhem was probably the 6th wire. This is added to a harness where a dome light is being utilized. It is normally wired to be 'hot' when the bike's ignition is in the 'off' position. When I first connected the trailer harness to the bike, it must have fed the dome light voltage back to the output side of the running lights relay in the isolator and then fried it with the contacts closed. I was fortunate that it didn't do any further damage to the bike.

 

The moral of this story? NEVER ASSUME the previous mechanic got it right!

[Yammer Dan]

Good point Stephen. Glad it didn't do any worse. If I run into major electrical problems I call for FrogMan....