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jberylec
03-09-2009, 03:30 AM
2001 MC tandem axle trailer for my X-9...
The rear passenger side brake light is lit and bright. No other lights work though. I've checked all the pins on the connector from my truck and they are all fine. Also probed each wire from the trailer connector and they all have power there too.

Does each light have it's own ground screwed into the trailer? Or do they all connect into a shared wire?

The last time out I knew the driver side brake light didn't work, but the running and reverse lights were working just fine. This is odd since the trailer hasn't seen water in between when they were working and now not working.

Thoughts? Help! Thanks in advance :confused:

TMCNo1
03-09-2009, 07:36 AM
Sounds like a bad ground.

thatsmrmastercraft
03-09-2009, 10:44 AM
Assuming you checked/replaced the left brake light bulb (also assuming you don't have L.E.D. lights) No1 is correct as usual.

bturner2
03-09-2009, 02:47 PM
I'll add a third for bad ground. To fix, start at one cornor of the tralier and go to each light. Pull the connectors out of the lights and clean everything up to like new condition (both male and female connectors). If you can't get it to like new condition relpace it. Coat all connections with dyelectric grease to protect them from corrsion and reassemble. While you have each light out trace the wires back to the frame and clean/grease each mounting point and terminal. When you're finished everything should work. Anything not working will need to have the voltage checked for a possible broken wire and condition of the bulb verified. Good moring project.

mayo93prostar
03-09-2009, 03:03 PM
the ground up front by the trailer connector is first place to check ground connection and then each light. one way i troubleshoot trailer lights is to use my batter charger to power one of the three pins (on a 4-way flat connector) with the red clamp (pos) and put the black clamp (neg) on the ground screw on the trailer. then check each light that is supposed to be lit and work it one at a time. short wires with smaller alligator clips help on this. i have found bad connections at the ground wire at the rivets holding the light on the trailer too. I drilled out the rivets and replaced with stainless screws and nuts. good luck.

jberylec
03-11-2009, 02:43 AM
Thanks for all the info! I dont think it's the main ground up front simply because the one rear brake light is bright as can be. Every other light is dead though. Very weird how they all go at once like that.

I guess I'll have to pry them all out and do as directed. Thanks again!

TMCNo1
03-11-2009, 09:23 AM
Thanks for all the info! I dont think it's the main ground up front simply because the one rear brake light is bright as can be. Every other light is dead though. Very weird how they all go at once like that.

I guess I'll have to pry them all out and do as directed. Thanks again!

Let someone else at a trailer shop sort out the problem and save the headaches, but if you insist on learning and DIY, two or three 3', 16 gauge wire jumpers with alligator clips on the ends, a cheap 12v test light will go a long way toward sorting the problem out one light function at a time. But, get a good clean ground between raw trailer frame steel and raw tow vehicle steel is the 1st priority. Do not try to ground to any part of the moving brake actuator parts. When I had no brakes on our '89, I could ground thru the ball and tongue, even with grease on the ball, but when I installed brakes in '97, the actuator would not allow a complete ground to the trailer frame and therefore I had to run a separate ground from the actuator tube to the van frame to make a ground.

thatsmrmastercraft
03-11-2009, 11:41 AM
Trailer wiring are probably 90% ground problems. Remember to keep to the basics. Start from the front and follow the power. Also work on one side at a time. Start with checking the side marker light on the side that has the functioning tail light.

Its easy to get overwhelmed when you look at the size of a trailer and all the lights. Strange problems almost always turn out to be a bad ground, however I have encountered a bad bulb before which had a direct short which really screwed things up.