M37 signal lights

[PoW]

And just to make it more confusing, there were two types of turn signal equipment.

The first (early) used a hybrid lever switch and control box to multiplex the stop/turn function into the mix. It was complex, prone to failure due to many active components in the box, and is rare now. It was also found on the 5/4 ton M715/725 Jeep trucks. That switch has wires coming out of it with terminal lugs applied to connect to the control box.

The later system used a standardized switch lever with a MS-series connector on the switch and a Bendix connector on the flasher unit along with rubber Packard connectors for interfacing into the main wiring loom. The earliest (and proper) of those uses a green indicator on the tip of the lever switch. This design didn't pan out very well, as the smacking of it up or down caused the 313 lamp in the handle to fail early & often. Later (and current) switches have the indicator lamp located in the switch body.

Both systems use the topology of one lamp on each rear side for the stop/turn function, as all M-series vehicles did. If you have a separate lamp for each of those functions, something improper from a civilian system has been imported and your NATO standard trailer receptacle will cause problems when used.

Both systems required the modification of the rear lighting layout. The proper way was to remove and discard the original BO marker & stop housing on the right, and add another service stop/tail/ BO marker combination housing as found on the left side. A separate BO stop housing (very similar to the M38/M38A1Jeep front BO marker) was added using a new bracket mounted under the new right side combo light.

Both modification systems required the addition of another wire from either the control box (factory done in later B1 production) or switch to the right rear stop/turn lamp and the proper pin in the trailer recep.

Dennis aka PoW

[Rick C]

I think theres some misunderstanding about that auxillary light and bracket. That light is supposed to have a cats eye lens. It is the relocated blackout stop light when they added 2 brake lights/directionals to the stock light setup

[DAP]

Yes, correct! But what I think works better is to convert it to a full lens if you want better visibility and then make that your only brake light. Leave the rear blackout lights as cats eyes if you want. Looks a bit more original even if it isn't.

I went another route on my M37 because I wanted the extra, extra, extra safety. What I did on my truck was convert the rear black out lens to a full lens and then hookup a 2 circuit for brake, turn signal and running lights. Almost no one notices it isn't original but people running up my tail pipe now better see when I hit the brakes or put on my turn signal.

Why did I want extra safety? To many unobservant nuts behind the wheel and I used to take my M37 out on the interstate. With the Hercules diesel, 4.89 gears and 11.00 X 16 Michelins I can top out at 68 mph (peak of the power band is 54) so I can almost run with traffic if I wanted to. It is also why I put 4 wheel power disc brakes on my truck.