Extra plug on old M37 light switch

70deuce · Post by **70deuce** » Mon Oct 05, 2009 4:13 pm

Anyone know what the extra smaller canon plug is on the old style light switch??? Thanks

powerwagontim · Post by **powerwagontim** » Mon Oct 05, 2009 5:24 pm

I was told that it was for the early turn signals, but it is only hearsay.
I would be interested to know for sure. I have tried to locate a 51 wiring diagram show it, but have not had any luck.
Tim

cuz · Post by **cuz** » Mon Oct 05, 2009 6:34 pm

The early Bendix-Scintilla light switch has an extra plug for the trailer harness which originally ran all the way from the switch's small plug to the rear trailer receptacle. This same switch was used on the M38 where it had the same harness setup. This switch was later superceded to a Bendix-Scintilla switch with only the unmachined boss where the small plug had been. As these two plug switches were attrited out the Army dropped the seperate trailer receptacle harnes and went to the molded rubber tap at the rear harness. These switches started phasing out in 1952.

Left is very early 10-34480 (G742 -7729684) Scintilla switch then center is 10-76555-1 (G742-7355600) Scintilla switch and right is first small single plug universal switch by Unicite # 160306 ( G749-7368702).

The G741 ORD 7 lists one more switch G742-7358637. I'm not sure which design this switch is.

powerwagontim · Post by **powerwagontim** » Mon Oct 05, 2009 6:49 pm

Great explanation Wes, thanks for setting me straight, and educating us all!
Tim

70deuce · Post by **70deuce** » Mon Oct 05, 2009 7:15 pm

Wes, man is that a great explanation. Thanks a bunch. You gave an answer I'm sure lots of people were wondering about. Do you know if that type switch is more valuable than the other types?

Phil C

cuz · Post by **cuz** » Mon Oct 05, 2009 7:30 pm

Phil,
I like to believe it is. Both of the Scintilla switches are completely rebuildable and it's a shame that the subsequent switches were all deliberately built as throw aways. They will all interchange and you can even plug in and run the newest one in todays active duty MV's.

knattrass · Post by **knattrass** » Wed Oct 07, 2009 9:09 am

Our 1954 came with the big single... bought a new current issue one... everything carried over including the 4 mounting screws.

gwalker · Post by **gwalker** » Sat Oct 10, 2009 9:49 am

The early type switches would be worth more to someone wanting an orignal type switch in there early MV, they are clearly different in appearance, and can be harder to find now. However if you were to use the 1st design you would have to have a 2 piece rear harness for the veh. if you wanted any wires to the trailer socket.

cuz · Post by **cuz** » Sun Oct 11, 2009 7:01 pm

Actually you can use the early 2 plug type with a late harness. You simply do not use the small plug receptacle.

Extra plug on old M37 light switch

Extra plug on old M37 light switch

And now we know the rest of the story!