So the '89 has a brake light out. It's not the bulb because the taillight works and I switched bulbs from the other side and both bulbs work on that side. Any ideas?

 

Ha! Never mind. Took the power probe and started poking around. Found a bit of dirt inside the connector cleaned it out and works perfect!! Wish they were all this easy!

 

I have the same issue, but it's not a dirty connector. When I have a trailer hooked up the left brake on the trailer dont work. I have probed as far back as I can and nada. Could this be in the brake switch?

Stu

 

Does the trailer work when hooked up to a different truck?

Does the truck do it to or is it just the trailer?

 

Truck does it, trailer is fine. It somewhere in the truck, I have a 5th wheel plug in the bed and it is forward of that. Everything else works, I'm wondering if it's the brake light switch do they have separate circuits for left/right?

Stu

 

I had this happen on my road runner once, turned out to be the turn signal switch. have some one watch the brake lights, and move the switch lever and see if there is any change.

 

Yeap the brake light switch feeds to the turn signal switch.

 

If you poked holes in the wire insulation I would clean it really good and smear silicone over the poke holes to help slow down corrosion.

 

this stuff works pretty good.http://www.globalindustrial.com/p/el...FUaCfgodIFwIfw
I got some at home depot.

 

Like Mark says, silly-cone doesn't adhere to vinyl wire insulation very well. Use a vinyl liquid tape product.

Lights to the back of the truck and trailer have 3 circuits. LT, RT, and Tail/clearance. The brake light powwer is routed through the multi function switch (turn signal lever) and is applied to whichever turn circuit isn't being used as a turn signal at the time. Could be either one or both.