Break lights don't work but everything else does

[army70deuce]

Hello all, Getting my new acquisition into working order but am unable to road test because the break lights don't work. I have full running lights, turn signals, emergency flashers, etc. but for an unknown reason no break lights. Before I start tracing all of the wires, is there a fuse box for the deuce that I should check? Haven't seen one so far.

1970 AM General
M35A2

 

[dabtl]

Try the brake light switch. Jump it to test.

 

[cattlerepairman]

Determine, whether you have the ''updated'' air pressure activated switch on the air pack (two wires connect to it). If so, you need air pressure to make it work.

My truck is picky; if the air pressure drops because the engine is off and I hit the brakes a couple of times, the brake lights will no longer come on.

 

[Speddmon]

sounds like the brake light switch, attached to the air pack...as mentioned, just jump across the switch and see if your brake lights work...if so, get a new switch

 

[Warthog]

Let's clarify.

His original question was : Is there a fuse box? No, there is no fuse box on the Deuces. There is a self reseting circuit breaker for the horn and heater (if equiped)

You need to jumper the leads going into the switch to test the lights. You can also check for voltage on wire 75 at the brake switch.

You need to use a ohm meter to check the switch itself.

I have attached a copy of the Deuce wiring diagram

 

[Barrman]

Make sure your top lever on the 3 lever switch is one click to the right in the 1 oclock position or all the way over with the head lights on. The power for the brake light comes from the 3 lever.

You can get to the plug without any tools, unplug it and put a jumper wire on the connector hanging down, it will spark as you push the wires in if power is getting to the switch.

 

[djimmy31]

I just had the same problem and it was a bad brake light switch air activated. I replaced mine in about 10 minutes for about 20 bucks.

 

[73X]

Brake light switch.

 

[jimm1009]

You have proven tha most (or all) of your wiring and bulbs are good due to the fact that the rear turn signals illuminate.
Jumping the switch is a really good start.
Of course, no air in the system and no activation of the air operated switch= no lights.
jimm1009

 

[CARNAC]

If you can't break lights, use a bigger hammer.

 

[jime]

I had the same problem. I found the switch, pushed on it and felt a little click, then, VIOLA, Brake Lights!

 

[army70deuce]

Sorry for the late response. After a dark cold night laying in the wet grass in some old BDUs with a flashlight I found the issue (I was driving it at O'dark 30 in the morning about 20 miles to a friends shop) I found that the wire was partially broken so, a quick snip and re wire with wirenut and electrical tape and its worked great ever since.