Hi

My 1995 F78 Fourtrak has had the waist-high rear lights fitted to it by a previous owner. They look great along with the bumper lights but, unfortunately, began misbehaving where (all) the brake lights were coming on completely at random. This came to my notice when my neighbours were telling me the lights were blaring away in the middle of the night! I don't use the car very often but needless to say the battery was flat whenever I wanted to drive it! So time to fix it….

At first, I assumed it was the brake light switch as a kick of the brake pedal would often switch the waist brake lights off. I fiddled around it with to no avail. As part of my tests I took out the brake light fuse but to my amazement the waist brake lights would still come on… derr…. It started to dawn on me that the waist lights were operating independently of the bumper lights.

I had noticed these phenomena seemed to take place when it was raining! I finally found out why! I removed the passenger side waist light cluster which revealed a void between the inner and outer quarter panels. This void was six inches deep in water! Not only that but I could feel a loop of wiring descending into the depths! On this loop were some relays which were connected to the waist lights. Now I think the relays connected to the waist lights were tripped by the bumper brake lights but because of the dodgy wiring they were also tripping the bumper fog lights and this was because of connections in the trailer socket. Because the relays were dipping in the water they were firing up irrespective of the brake light pedal or fuse for that matter!

I eventually took this to an auto electrician….. and here's the painful bit…. £250 to get it all ironed out!! ouch! We've drilled drain holes in the void !!

So if you've waist lights and they are firing up at random check for an olympic size swimming pool in the back of your truck!

HTH someone