Rookie needing headlight circuit help

[local907]

Hello all,

I am new to your world of M37's, and am here seeking help for a friend that recently purchased a 1953 model. I don't have any experience in classic military vehicles, but this thing is in beautiful shape. An older gentleman spent years meticulously restoring the vehicle, but unfortunately passed away recently. This led his wife to sell the truck, though she didn't appear to know many details about it's current status.

The truck works almost perfectly, and includes an impressive array of random military equipment and spare parts. The only real issue we have found so far is related to the headlights. When the (single-connector) light switch is moved to the drive position, it immediately trips one of the circuit breakers behind the dash. I eventually unplugged all of the front lights (headlight/bo marker/bo driving) on both sides using the connectors on the front fender, and found that it still trips the breaker every time. Running a jumper from the horn's 24v feed directly to each headlight, I was able to confirm that they do at least work.

The truck will be leaving town on a ferry early Thursday morning, so I don't have all that much time to troubleshoot. For the time being, I ran wires directly to each of the headlight low-beams and put them on a switch in the dash.

I have read that those three-lever switches can go bad. Does this sound like a bad switch? Or should I continue hunting for any potential shorts between the fender/firewall/dash?

[local907]

Sorry about the double-post, I didn't see that my first attempt needed to be approved.

[NAM VET]

I found some chafing and wear thru on some of the wires down where the vent lever rubbed them when I moved it to open and close the vent. Protected them, then secured them out of the way of my lever. And I also had a military aftermarket switch go bad too. NV

[local907]

Thanks Nam, I'll take a closer look at that vent lever area.

Do you happen to remember the symptoms you were experiencing when the switch was going bad? All of the other positions on this switch appear to be working normally, it's just that run/drive position flaking out.

[just me]

I had the clutch pedal rub through a wire at the dimmer switch

[Saberr]

Just like nam hinted on, i would first do a visial check if all wires are fully intact first. Remeber if the wire wasn't replaces, then its over 50 years old. Can also do a quick check if the douglas numbers are connected to the proper ones. No matter what people belive or say, military stuff is not perfect or indestructable.