The other night a friend of mine used my truck to tow his boat to the water..no problems at all towing it. When I followed him back home (I was driving his car, following my truck) I noticed that the driver side brake light was out. No problem, I'll fix it the next day. When I went to check the lights everything worked on the truck except the brake lights. No rear flashers or blinkers either. The running lights are fine. Bulbs are both fine but I replaced them just in case. Nothing. FWIW, I had a windshield leak that would leak RIGHT INTO the steering column. Fixed that last weekend but we had an awesome amount of rain so the column did get wet. Could this be affecting anything? I checked all the obvious-fuses-bulbs-connections for corrosion, etc. Any thoughts on this one?

Roger

 

The water could have taken out the multifunction switch in the column .

 

Not sure if this is your problem but a few weeks ago I got stopped and ticketed for no brake lights. I didn't know I had a problem, turned out the brake switch under the dash was the problem.

 

I thought about that but the 3rd brake light works fine. I may be wrong, but if the brake switch was defective, wouldn't the 3rd barke light not work, too? Seems like it might indeed be the column switch?

Roger

 

The multi function doesn't have to blink the 3rd brake light so it's not affected like the brake lights.

 

How did you check the fuses? If all you did was pull one out and give it the 'ol eyeball inspection... well that ain't good enough. Take a look at the top of each fuse (where the rating is marked) and you'll see a place where you can touch a meter probe or test light to each side. What you do is (with the fuse installed) take your meter/test light and connect one side to chassis ground. Take the other side and probe each fuse, one side of the fuse at a time. For each fuse that shows power on one leg, the other leg of that same fuse should show power also.

When you find a fuse that only has power on one side, you've found a blown one.

Some fuses won't have power on either side, try turning everything electrical on to energize these circuits. Of course, if you can't get power then it's likely that there is another fuse upstream of here that feeds it and several others, and it's blown.

If you find a blown fuse, look at it carefully in bright light. If there's a clean break in the element (the wire inside), then it blew due to an overload. If there's burn marks and carbon deposits inside, then it blew due to a dead short.

Fuses hardly ever fail for no reason. Whatever caused it may not come back right away, either. These are the worst types of problems to track down.

And... don't use cheap no-name fuses when replacing them. Get Cooper/Buss, and know that you can count on them to save your wiring next time.

 

Sounds to me like there's a problem with the trailer wiring. Check your trailer connector pins and the pins on the truck side, one or the other could be recessed. Also find your trailers brake wire and ohm it out.