I’m freshening up the interior of my 40 standard coupe and one project has led to another, and another....and, ya you know. So I pulled the steering column to replace a butchered column drop, then the dashboard came out, and I realized just how bad the wiring harness actually is, so I’m now doing a full re-wire of the car. I’m starting this thread because I know I’m going to have many questions as I work through this project. To get started I purchased a dash harness from Tyree Harris. A few questions to start: 1) behind the D/S dash there is supposed to be a block with an ignition resister and a headlight circuit breaker....it’s missing. There is only the resister, no breaker. Do I need this or is there another option? 2) I noticed the battery has negative to ground. It’s all original 6v system. Is there a way I can tell if this was done by accident (which I suspect) or intentionally? If I switch it back to positive ground can I damage anything? I attached a pic, if you zoom in on the upper left side you’ll see the resister and missing circuit breaker. Thanks!
Since you don't seem to know very much about electrical systems, I suggest that you buy one of the many books available on the subject because invariably one answer just leads onto another question and it is better to take in the full picture.
Yes you need the circuit breaker, there are other connections that come off of the head light breaker for there power feed, plus that's what protects the head light circuit, since these cars don't really have a fuse box. I am not a fan of how these cars were originally wired, so if it is anything other than all original, I rewire them how I want. with an actual fuse block, and make my own harness.
None of your wiring is original '40 Ford wiring in that pic, so I would guess whomever did it must not have followed Henry's design. Now you should probably follow Tyree Harris's design, unless you have good reason to change it.
I took a second and did a Google search and it looks like this is a factory style replacement harness. Didn't it come with any install info?
Thanks for the responses. Truth be told, wiring is my weakness. The harness is factory correct and came with a simple color coded diagram which I intend to follow. That should bring me back to stock. With that circuit breaker gone, I guess the headlight wiring was unprotected. I’ll purchase one and install. I guess the battery being grounded improperly wont matter once I install the new harness according to Tyree’s diagram.
I'll try to remember to look tomorrow for ya but I believe it's a 30 amp breaker. I wouldn't leave one out. They don't know if they are 6 or 12 volt. And yes, I'd go back to positive ground and be a bit leary of the Voltage regulator since it has been in the system with power in reverse polarity. Prior to running after installing new harness I'd re polarize the charging system just for luck. You may or may not still have a charging issue.
Look here and find your needed diagram. http://www.vanpeltsales.com/FH_web/flathead_drawings_electrical.htm
I don't think I'd just pitch the old one without giving it a chance. If it was charging last time you drove it no reason to think it can't again. Polorizing so it recognizes current direction may do the trick. Doing it can't hurt a thing.
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