The Stovebolt Site Forums The Shop Area The Electrical Bay Small switch on top of starter

I have a 1947E COE truck, all original. I have finally located the problem I’m having getting it to run. There is a small switch on top of the starter which is activated with the foot starter. The switch seems to be in line between the coil hot side and the distributor. What does this do and can I just run from the coil to the dist? This switch is worn and causing voltage drop at the distributor.

Tom,

I replied to your other thread, here. That's probably a starter solenoid. If it's wired between the coil and distributor, that sounds pretty weird. It shouldn't be like that. There shouldn't be anything between the ignition switch and coil and the coil and distributor except wire.

If you can post a pic of it, that would help us figure it out for you.

Here's a picture of the wiring diagram for 48-49 trucks showing the solenoid.

OK, I took a look at the 47 wiring diagram and it shows a "reversing switch" that looks like what you're seeing. It is wired between the coil and the distributor.
It's shown on HERE. I'm definitely on that one. I'll take a look at the rest of that manual and see what it might be for.

That is a polarity reversing switch that is supposed to prevent, or at least diminish metal transfer from one contact of the points to to the other. Each time the starter is engaged, the switch reverses the current flow. Bypass the switch, but at the same time run a ground wire from the rigid point to the distributor housing. That particular distributor has the breaker plate insulated from the housing.
Jerry

More info on that reversing switch. It's there to "increase the life of the points". Sounds like a likely spot for trouble to me. More info on this page and this page. Since it's a one year only thing, as far as I know, GM likely found out it was more trouble than it's worth. The points have to be isolated from ground at the distributor and the ground is provided thru that reversing switch. Unless you're dead set on originality, I'd remove it and wire from the distributor to the coil contact and from the other distributor contact to ground, like the 48 and later trucks are. You'd have to pay attention to which distributor contact is normally grounded thru the switch when the starter pedal isn't mashed so that point polarity is "normal."

[on edit] Thanks Jerry, I figured you have probably seen that Rube Goldberg setup before. Seems like a problem waiting to happen.

It was one of those "looks good on paper" things that train drivers are famous for dreaming up. One of the most amusing night classes I ever taught had me working with five young engineers from the fledgling Saturn manufacturing plant in Spring Hill Tennessee. Somebody in upper management had wisely decided they needed some exposure to the experience of fixing cars, instead of just designing and building them. They were enrolled into a 10 week "do it yourself" course I had been teaching for several years for non-mechanics. Most of my students were young professionals, soccer moms, and other people who just wanted to learn to change tires, do brake jobs, change spark plugs, change oil , and do other minor maintenance on their own vehicles. That was a fun experience for everyone involved!
Jerry

Excellent guys thanks for the help. I noticed it does reverse the current. That is very strange and much better on paper. Off it comes and this things going to start!