[Jacques Reed]

Hello Hanno et al,

I realize this is an old thread but seeing this link from Snakes Alive this may be of use to fellow restorers. I think I may have covered some of it before but it might be useful to put it all together here in one place with toggle switches.

From what I have seen, there are two types of light switch plates used on Ford CMP vehicles. Early ones as shown on the left, in brass, could only control one lighting function with one switch. Around 1943, based on the wiring diagram from the 1943 Maintenance Manual, someone decided they wanted the ability to control various combinations of lights with one switch only. Perhaps a military requirement to avoid leaving a light on under various operating conditions?

Early vehicle's light switch plates therefore only need to have single pole-single throw (SPST) switches installed to work as required. There are many automotive and marine switches that will do the job and look nearly correct.

When you get to the later instrument panel switch plates, shown or right, here is where the difficulty arises if you want the lighting arrangements to agree with the switch plate.

In effect, the switches are triple pole-single throw switches (TPST) as used on this type of plate. The input side is made common. The output side has three independent poles. These are almost never used anywhere hence very hard to find.

If you look at the diagram from the 1943 Maintenance manual you can see that the three poles on the lighting panel switches are independent of each other. This independence is the key to being able to make various combination of lighting from just one switch. When you throw a switch it only sends current to the designated lights by way of the "jumps" between the switches. If you use a SPST switch in this situation and connect the designated lights to the output side of the switch with "jumps" any switch when thrown will light up all the lights- obviously this is is not what the designers intended and why TPST switches will only work for this situation..

Hope this is of some interest.

Cheers,