M38 Jeep and M100 trailer
- henrydes
- Contributor

- Posts: 96
- Joined: Mon Aug 30, 2010 6:00 pm
- Location: Rose New York
M38 Jeep and M100 trailer
I am looking for the best way to rewire either the jeep or the trailer so I can have running and stop lights. Any help would be appreciated
- wesk
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- Location: Wisconsin
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Well there are many ways but each depends on the current wiring of each vehicle and the operating voltages and the type of light fixtures. If you will give us enough information we may be able to help you. 
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Mjeeps photo album: http://www.willysmjeeps.com/v2/modules. ... _album.php
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Mjeeps photo album: http://www.willysmjeeps.com/v2/modules. ... _album.php
- henrydes
- Contributor

- Posts: 96
- Joined: Mon Aug 30, 2010 6:00 pm
- Location: Rose New York
m38 and m100 trailer
Both the jeep and the trailer have stock wireing..I have heard that wire ing can be changed around on the rear of the jeep which will operate the lights on the trailer. I changed the lenses on the trailer to red lenses. I would love to have running lights and brake lights. In case you dont notice I am not an electrician, so the simplest way would be great.. Henry
- wesk
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- Location: Wisconsin
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If both vehicles are stock 24 volt then the simple method is to use install a left hand tail light assembly on the right rear of each. This gives you a red tail & stop lens on both sides. I will not explain adding turn signals here.

These are the lamps you want on the back of the jeep and the trailer.
Then you must decide on how to power the right side service stop and tail on the trailer. 1-You can re-arrange the wires on your trailer receptacle at the back of the jeep or 2-you can re-arrange wires at the back of the jeep and the back of the trailer and leave your trailer receptacle alone so it can be used with any other trailer.
I would suggest making the simple wire adjustments at the rear harness of the jeep and at the rear harness of the trailer only.
All military harnesses have metal wire numbers at the end of each wire.
The original left light assemblies have wires:
21- Service (red) tail lamp
22- Service (Red) stop lamp.
24- BO tail (marker) lamp
The original right light assemblies have wires:
23- BO stop lamp.
24- BO tail (marker) lamp.
Leave the left light assembly alone.
Install a serviceable left light assembly on the right side.
Tape up the original right side wire #23. You won't use it.
Connect wire # 24 to the same bottom lamp as it was connected to on the old light assembly.
Now you will need about 12 feet of 16 gauge wire for the jeep. Cut the wire in half for two 6 foot pieces. Use a couple of quick splices and splice into the #21 and #22 wires at the left tail light assembly. Mark the other end of each of the new wires with the correct #21 or #22. At the other end of those two wires you should build connectors to match the two hanging from the new right side light assembly. Now connect the new 21 to the right light's 21 and the new 22 to the right light's 22. The jeep is done.
To do the trailer it is essentially the same except since the trailer harness runs down the right side of the trailer you will use only two short about 10" each 16 gauge wires and quick splice them to the left light's 21 and 22 wires right where they come out of the bend in the harness.
If you do not wish to retain any BO functions you can simply keep the original right light assembly, add a full red lens and connect wires 21 & 22 to those two connectors with 22 getting the larger light bulb.



Quick splice

These are the lamps you want on the back of the jeep and the trailer.
Then you must decide on how to power the right side service stop and tail on the trailer. 1-You can re-arrange the wires on your trailer receptacle at the back of the jeep or 2-you can re-arrange wires at the back of the jeep and the back of the trailer and leave your trailer receptacle alone so it can be used with any other trailer.
I would suggest making the simple wire adjustments at the rear harness of the jeep and at the rear harness of the trailer only.
All military harnesses have metal wire numbers at the end of each wire.
The original left light assemblies have wires:
21- Service (red) tail lamp
22- Service (Red) stop lamp.
24- BO tail (marker) lamp
The original right light assemblies have wires:
23- BO stop lamp.
24- BO tail (marker) lamp.
Leave the left light assembly alone.
Install a serviceable left light assembly on the right side.
Tape up the original right side wire #23. You won't use it.
Connect wire # 24 to the same bottom lamp as it was connected to on the old light assembly.
Now you will need about 12 feet of 16 gauge wire for the jeep. Cut the wire in half for two 6 foot pieces. Use a couple of quick splices and splice into the #21 and #22 wires at the left tail light assembly. Mark the other end of each of the new wires with the correct #21 or #22. At the other end of those two wires you should build connectors to match the two hanging from the new right side light assembly. Now connect the new 21 to the right light's 21 and the new 22 to the right light's 22. The jeep is done.
To do the trailer it is essentially the same except since the trailer harness runs down the right side of the trailer you will use only two short about 10" each 16 gauge wires and quick splice them to the left light's 21 and 22 wires right where they come out of the bend in the harness.
If you do not wish to retain any BO functions you can simply keep the original right light assembly, add a full red lens and connect wires 21 & 22 to those two connectors with 22 getting the larger light bulb.



Quick splice
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Mjeeps photo album: http://www.willysmjeeps.com/v2/modules. ... _album.php
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Mjeeps photo album: http://www.willysmjeeps.com/v2/modules. ... _album.php
- henrydes
- Contributor

- Posts: 96
- Joined: Mon Aug 30, 2010 6:00 pm
- Location: Rose New York
m38 and m100 trailer
Wes...Thanks for all the info, as usual you have bailed us out.