Toggle switches

[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,

[M.Morren]

Hi,

I'm a bit puzzled on the intended manner of working for the lighting. I'm currently fixing a problem with the lighting system in my '43 C8A and was wondering if anyone can help me.
I am hearing some different stories about what the switches will do in different scenarios.

When I look at drawings made of the wiring I come to the conclusion that each switch will operate a different set of lights. (This is confirmed when I look at the plate behind the switches (Tail, Tail+Side and Tail+Side+Head).
But... Someone told me that the Tail and the Tail+Side switches must be ON to turn on the marker lights. (As a sort of fail-safe for blackout driving. American vehicles have a system where the light switch cannot be pulled out completely without pushing another button on the side). The same goes for the headlights. So the Tail, Tail+Side and Tail+Side+Head switches must be ON to get the headlights to turn on.

My C8A is currently wired in a way so that a combination of the above happens. I have to set the Tail to ON to get the Tail+Side and Tail+Side+Head to work. But I do not have to turn on the Tail+Side to get the Tail+Side+Head to work.

I do understand how the switches work, I just don't know in what manner they are supposed to operate. I would really appreciate it if someone could help me.

[Jacques Reed]

Hi Marty,

Are all your switches original? Even if one is substituted for a SPST type switch the combinations won't work as designed.

Basically the power supply side poles of the switches are all common. think of them as connected to a bus.

The isolated poles (isolated from each other) on the output side is what makes it possible to have the various lighting combinations with just one switch thrown.

If all switches are original, it might be worth putting a multimeter on the switches to check the continuity that all the 3 power supply terminals are common to each other and that all 3 output terminals are isolated from each other.

Also check that all the jumps are correctly wired in and all jumps present.

Hope this is of some help or points you in the right direction anyway.

Cheers,

[M.Morren]

Hi Jacques,

The 3 TPST switches are original and working. I have traced all the jumps and found out that they are all over the place (most power comes in on the wrong side. That's why the Tail+Side and Tail+Side+Head only work when the Tail is on). I understand how and why the current config works.
But what I would like to know is, how is the lighting system supposed to work? See the scenarios in my earlier post. Which one of those is correct?
And is there an explanation as to why I hear different things than that I see in the manual? Did they change the config but nog document it in the manuals?

Thanks for your help!

[Jordan Baker]

Hopefully this drawing I made up helps with your wiring and for figuring out how these switches work.

On the back of the switches there are 5 usable sockets. The two on one side are for the power into the switch. The three on the other side are for going to the various light circuits.

The tail light only wiring starts at the top switch. It then has two jumper wires that go to same socket on the next two switches. It’s the lines wth the neon yellow.

The side lamps only goes to the middle switch and has a single jumper that goes to the same socket on the next switch. It’s the lines in the blue.

The headlamp wire is a single wire and goes to the dimmer switch. It’s the red wire.

The green lines are the power in.

The important thing to realize is that the three out sockets on the three switches are all independent.

So if you want only the tail lights on you turn the tail light only switch to on. If you want tail lights and side lights only, you only need to turn on that switch.

If you want head lights on you also get tail and side lights. You simply turn on that switch.

Hopefully this helps. It took me a bit to sort it all out but once I drew this diagram up it all made sense. I need to see where each wire goes to exactly what socket.

[M.Morren]

Thank you Jordan,

I actually used your diagram and it did help me understand the working too!
Now I just have to figure out how the gentlemen that told me that all three should be turned on to get the headlights to turn on (as a sort of failsafe to not accidentally turn on the bright headlights) got that info from. He dismantled several Chevs so he must have seen some different configurations. It is possible to wire the switches in the above mentioned way due to the independent output sockets.
I'll visit him in a couple days to see how his Chevs are wired and will share this with him to see what he thinks.
Thank you both for the help and if anyone else has some extra comments, feel free to message me or put it in this thread!

Cheers!

[Harry Moon]

On my C15A I set the switchs up as factory all three torn on the tail, bottom two turn on the front markers and only the bottom does headlights.
On my C60L where I wired each independently with fuses and I chose to install a relay for the headlights.