No brake lights on trailer

[CHIEFSONN]

No brake lights on truck & trailer

Last night after hooking up my trailer m105 to my m932a2 I have no brake lights, the rest of the lights work,rt turn left turn & running light. how do I test the plug or truck s for the problem so come Thursday i will have brake light . thanks

 

[jasonjc]

Check the ground on the trailer. If you have right and left turns you should have brake lights. Same wires and bulbs.

 

[Trailboss]

If the turn signals and hazard lights are working, I'm thinking probably the switch at the brake pedal.

 

[Ajax MD]

The initial post is a bit ambiguous.

WHERE have you lost brake lights- The trailer? The truck? Both?
IF brake lights are lost on both, What happens when you unplug the trailer? Do the truck brake lights function again? Are they still out?

 

[gimpyrobb]

In the past, I've had issues with the ground on the truck side.

A dvm hooked to ground on the vehicle then plugged into each pin should tell you which wire on the truck is or isn't working. Gimme some time and I will find the pins you need to test.

 

[gimpyrobb]

https://www.steelsoldiers.com/showthread.php?37452-My-towing-light-setup-MV-s-Civi&highlight=

 

[CHIEFSONN]

Ajax MD with the trailer unplugged the truck still has no brake lights

 

[juanprado]

If this is for the m939 series, I suspect the stoplight switch is bad. It is on the metal airline hugging the frame down from the cab. The oe has military packard connections. Easiest fix is haldex universal civy 2 terminal air brake switch and just make an adapter to your military wiring if you do not want to cut oe wiring. Napa or any hd store

https://www.haldex.com/en/na/electrical/electro-pneumatic-switches/be13250/