g741.org

Hey guys,

Here's a question for those of you well versed in the electrical system of the M-37. I am getting ready to install the Signal Stat turn signal system on my M-37. I'm up to speed on doing that install thanks to several members of this forum. But there is one thing I'm not sure about being that my manual doesn't seem to show the trailer receptacle wiring schematic. I have an M101-a1 trailer fresh from the military and I want the turn signals to work properly on the trailer as well. So here's my question. Is the trailer plug receptacle on the rear of the M-37 merely piggy-backed of the tail lights of the M-37 so that whatever happens with the truck taillights will be duplicated on the trailer? Or is the receptacle wired completely separately from the taillights requiring me to modify the receptacle wiring as well? I hope I'm being clear enough here. Bottom line is this..... after I install the turn signals on my truck will I have turn signals on my trailer when I plug it in?

Assuming you will replace the right rear light assembly with another left rear unit on both the truck and the trailer so you have a service stop on both sides. Or are using the late M series composites with 4 wires each side. The trailer receptacle is supplied from the harness at the left rear corner of the truck. The harness splits wires to allow for the second light and the receptacle. The later manuals offer you the M37B1 wiring which includes signals and the receptacle. You'll need to insure you have the needed wires pinned in the receptacle and you will have to mirror your efforts with the truck's tail lights and wires on the trailer. Please note that the very early trucks came with a dual plug light switch that ran a separate harness all the way back to the trailer receptacle. Not many of these left out there.

The following is from my M38 web site but the evolution of the M37 main light switch went the same route.