M1101 Trailer Light Problems

[jwhit612]

Ok, this will probably be an easy solve for you guys, but I'm new to the whole military trailer thing. I just bought an M1101, manufactured in 1997, and of course, one of the first things I do is get on Amazon and buy some 12v LED replacement lights for the trailer. I looked up the numbers and it looked like I could replace all the bulbs all the way around with one LED bulb. I then connected a 4-pin wiring harness to the existing wireing (someone had unplugged everything under the trailer before I bought it so I just connected everything together right at the terminals). When I plugged it in, some of the lights worked and some didn't. Most of the running lights on the driver's side worked but the blinker/break light didn't, and nothing on the right side worked. After closer examination, some of the bulbs were blindingly bright but some of them were just barely glowing. You couldn't even tell it was glowing unless you were looking right at the diodes. It's not a bulb issue because I can swap bulbs one that's bright and one that's not and they'll reverse, so it's definitely a wiring thing. The first thing I thought of was a grounding issue but that shouldn't affect some lights and not others should it? What am I doing wrong?

 

[Tinstar]

Welcome to Steel Soliders

Grounds will effect some lights and not others.
I assume that you checked all the wiring underneath before hooking anything up.
Most of these trailers had a hard life in service and were not that well maintained.

I would physically refresh every ground you can find.
Don't just look at it.
Follow all the wires along frame and check for anything frayed, chewed, etc.
The tail light placement on the M1101/2 also made it prone to damage from behind due to cargo hitting/rubbing against it.

Double check to make sure the wires are hooked up correctly. It happens.
If it was acquired through a surplus auction, it probably has been abused and neglected.
If purchased from individual, who knows what was messed with before you bought it.

If you haven’t already, Check all your bearings, seals and brakes.
Remove, check and repack with new grease.
The M101 snd M1101 series trailers are notorious for bad bearings and seals.
Brake issues too. All to neglect.
Also check your surge brake system.
Most parts are available commercially.

That trailer TM is available for download in the TM section.

Report back what you find.

 

[Digger09]

It could also be the tow vehicle not the trailer. Was the trailer hooked to tow vehicle? Do you have another truck to hook to?

 

[Tinstar]

It could also be the tow vehicle not the trailer. Was the trailer hooked to tow vehicle? Do you have another truck to hook to?

X2

 

[oregonfirefighter]

I have wired several by switching out the MIL male plug with an 7pin style plug. All has been fine and dandy till the last two units. The drivers front clearance light burns dim :/

 

[Mainsail]

...but the blinker/break light didn't...

They're brake lights- not to pick on you, but the next guy that does a search for this issue will not find any results if he uses the correct spelling.

Explain what you started with as far as the wiring. You say someone unplugged everything under the trailer.... There is a junction about mid way back that has a series of connectors; just there or in other places as well?

To what and how did you connect your four-pin harness?

 

[Tinstar]

The OP hasn’t chimed in since their first post.
It’s probably another......post once, then they figured out the issue and never will update or even post again.

Of course that helps no one.