Bulb Voltage interchange Chart (6V 12V 24V, for trailers and trucks)

attached is a chart the guy at NAPA gave me when he sold me some 24V lamps to replace the 12V ones in my civvy trailer.

The chart covers many 6V, 12V, and 24V lamps found in vehicles

PDF and GIF are same. PDF is higher resolution.

Just be advised that the standard 12V 1157 2-element bulb and the listed 1662 24V 2-element bulb are actually wired opposite. I had to do some wire swapping to make that exchange work. Haven't found a TRUE 24V "1157" replacement.

I got the 1662 and filed off one of the pins on the side. This allowed me to put it in the socket backward so the lights worked without rewiring. Worked just fine.

There is one in the technical articles section already. Everyone should run through them once in a while just to see what is there.

http://old.steelsoldiers.com/index.php?module=pagesetter&func=viewpub&tid=3&pid=45

It is a beter copy too.

Thanks for the note about the 1157 vs 1662. I wonder what idiot designed them that way?

Since I will be wiring an M105 pigtail in, I can take that into account and swap the wires (might have to add a pair of diodes between the 12V tail light source and each 12V tail light filament depending on the trailer's existing civvy harness).

- and while we are at it, in the same section, Lights Bulb NSN from PS 670:
http://old.steelsoldiers.com/index.php?module=pagesetter&func=viewpub&tid=3&pid=77

Job done. It was simplest to use two surplus "bridge rectifiers" taken from a scrap power supply to route the voltages properly. Works perfectly and no annoying wire-swapping required.

The user has only to install the right bulbs depending on if it will be towed by the 12V civilian vehicle or the 24V military vehicle. There are two pigtails. One fits the M35 and one fits the pickup truck. Instructions are attached so that anyone can do this pretty easily. The connections and diodes can be stuffed in a plastic or metal box if necessary.

The attached file has been submitted to the Technical Articles section of the Resources.