MTFCA Forum

I am updating and cleaning up the 30+ year old wiring in my Tourer, mostly so that it looks nice. While going through the wiring, a previous owner has run a red wire from the 'coil' location on the ignition switch, to the coilbox (I think that's the 'Mag" lug its attached to). This is a 1920 engine and the car has a starter and generator, everything functions and starts well. What is the intent of this extra wire that does not show up on the wiring diagrams?

I have not yet replaced that wire, but I am afraid to start the car not knowing what its for. These photos are taken just as I was getting started on replacing the wiring, some wires are disconnected in the ignition switch photo intentionally to show the location of this red wire. The wires are much cleaner and organized now.

Thanks!!

Take it off and see if still runs on both battery and magneto. The single wire from the switch to the coil box terminal functions for both, depending on which way the key was turned. The terminal the red wire is attached to on the coil box, would not be used or needed when the switch on dash is used.

The "coil" wire is the one (and only) wire which should go to the coil box. The ignition switch is a wig-wag switch which routes either the MAG post to the coil box, or the BAT wire to the coil box.

Your coil box is for a non-starter car, which would have had a switch directly on the front of the box...I'll bet there are some slots in the front of the box and some old evidence of a missing switch. Now the question you'd ask, if the post wasn't there what goes into the hole in the firewall and the answer is "nothing, it's just an empty hole. Your car very likely was originally a non-starter car which was updated with a new hog's head and starter and the extra post is the remnants of the earlier switch system. If it has side oil lights, it was for sure a non-starter car as born.

As wired, you are running the ignition source (MAG or BAT) to both old posts, where there should be only 1 post and that would be the post nearest the steering column...you're simply applying the source to both ends of the strip on the bottom of the box. The previous owner appears to have had a fundamental misunderstanding of how the car operated and how it should be wired, and with an extra post which serves no purpose when a dash switch is in use, probably said "hell, something must go there!!"

Unless something else is very seriously askew, nothing should be harmed and no loss of operation should be found if that red wire was removed completely. That said, there seems to be no end to goofiness which can be built in to these things for the next guy to cypher out.

Now, something I'll add: those two posts were a feed to the original switch and a single wire emanated from the switch to solder to the bottom strip. There has to be some modification of things inside so as to make the feed go through the post and directly to the bottom strip. I highly suggest a thorough trace out of the box with an ammeter and study the solder connections. Something goofy is going on inside. While it appears to work as modified, I'd want to know what's going on for peace of mind and to have fore-knowledge if further or future troubleshooting brings you back to the box

all the best and good luck

I love the improvised cover on the back of the horn!

Allan from down under.

As Scott described: the coil box is a likely for a non-starter style have a two posts (mag & bat) as the voltage source for the coils. It may have been done because the BAT wire from the switch to the post on t he box is broken. Another possibility is that someone may have put new wood in a "correct" coil box and inadvertently connected the wire from the center strip to the MAG post instead of the BAT Post. The wiring diagram "bottom view" is referring to the groves cut in the wood. Currently all replacements are made for the earliest style box. Once wired the grove side goes face down into the box - its easy to get turned around when wiring it up. Tried to show that in the attachment
If the red wire is removed and the car doesn't start just move the wire that is on the BAT post to the Mag Post its long enough. Again the "bottom" view is the underside of the wood - the "top" has the metal strip

It is very likely that red wire was run for a reason. It could be done in a much cleaner manner though.

Most likely you can remove the red wire all together and just move the black/yellow wire on the bottom driver side of the coil box to the terminal on bottom passenger side of the coil box where the red wire is currently connected.

The other option is to still remove the red wire and to leave the black/yellow wire on the bottom driver side of the coil box. Then just run a jumper wire to the bottom passenger side of the coil box where the red wire is currently connected. This would be the exact wiring as it is currently, just a much cleaner way to do the same thing.

Terry

Thanks, everyone! I'll be testing it out this weekend. I'll let you know how it goes.

Just to give you all an update, that red wire was superfluous. I installed new wiring and without that red wire, everything is working great.

looks good!