55 wiring issue

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harleyhoot
Posts: 14
Joined: Mon Mar 09, 2015 6:24 pm

55 wiring issue

Post by harleyhoot » Fri Feb 23, 2018 2:03 pm

I own a 55 that is a daily driver with some modifications. I just installed LED tail light lamps on this car for better visibility in the day time. As I was testing the lights I pulled the light switch out and the engine started cranking........with the shifter in park and the ignition switch off !. I have had an issue with the dash light dimmer not producing dash lights except for in a certain position. I found that as I turned the dimmer when the lights came on the engine would start to crank....weird. This car was converted to 12 volt with alternator but has the old 6 volt wiring. I noticed that the light switch pretty much introduces battery current to the rest of the dash but is it possible that the switch can fail internally and cause the engine to spin? If not I assume that there is a short between the solenoid wire and light circuit in the harness???? Has anyone experienced this ???

fordrodsteven
Posts: 54
Joined: Mon Apr 24, 2017 7:46 pm

Re: 55 wiring issue

Post by fordrodsteven » Fri Feb 23, 2018 2:48 pm

I perused the wiring diagrams. It doesn't seem sensible to me that the headlight switch could send a signal to the solenoid to crank the car over. It sounds like something may have been wired wrong. I would check the wires at the ignition switch and their connections to the headlight switch to insure they are proper. The diagrams show many things connected at the headlight switch and also at the starter solenoid but the circuit from the ignition to the starter should not "make" unless the ignition is turned to the start position.
Steve

CSavaglio
Posts: 235
Joined: Sat May 28, 2016 11:37 am

Re: 55 wiring issue

Post by CSavaglio » Fri Feb 23, 2018 3:10 pm

It's a short. Check the wires under the dash. It sounds like a short from either the headlight switch or wires to the solenoid post on the ignition switch. The two switches are near each other.. Since it seems like the dash lights are what's triggering it, a wire going to the gauge lights is shorting to the ignition switch solenoid post or wire.

The early plastic coating on wires from that era are notorious for shrinking over time and exposing the ends by the ends. It could also be cracked insulation shorting.

fordrodsteven
Posts: 54
Joined: Mon Apr 24, 2017 7:46 pm

Re: 55 wiring issue

Post by fordrodsteven » Fri Feb 23, 2018 3:30 pm

Upon review of my earlier post I afterwards realized that you have had this car operating and just changed the tail lights.
All my diagrams show four terminals at the ignition. One is the "B" terminal which is battery power to the ignition. One is the "A" terminal which I think is powered when in the accessory position. One is the "C" terminal which is powered when in the run position. (I'm not 100% positive but I think the "A" terminal is also active when in the run position) The fourth terminal is the "S" terminal which would be the start (or solenoid) terminal. This wire would send the signal to engage the starter solenoid to crank the engine. That wire is somehow getting a signal when you are using your headlight switch. I agree with CSaviglio that there is a short touching to that circuit and causing the car to crank.
Steve

harleyhoot
Posts: 14
Joined: Mon Mar 09, 2015 6:24 pm

Re: 55 wiring issue

Post by harleyhoot » Fri Feb 23, 2018 4:14 pm

thanks guys for the input. If something is wired wrong then it's been that way for several years as this car is driven. I will add also that for some reason since put back on the road several years ago that I noticed that the only time the clock would work is when I turned on the lights so something may be wired wrong as far as that goes. I have a new light switch that I bought some time ago and am going to start with that replacement when I crawl my old butt under the dash in a bit. I figure that when I replace the switch I'll test again and see if the problem is corrected.....if not then I am going to trace the wire from the solenoid to the switch by opening up the harness.... or either un-hook that wire competely and run a separate new wire to the solenoid.

harleyhoot
Posts: 14
Joined: Mon Mar 09, 2015 6:24 pm

Re: 55 wiring issue

Post by harleyhoot » Sun Mar 04, 2018 4:23 pm

well, finally found the issue with cranking when the light switch is pulled. I was going to just run a jumper wire from the ignition switch and by-pass the original but didn't want the car to start in any gear so after a couple of cold ones I realized the only way this problem can happen is if there is a current short is between the neutral safety and the solenoid. I pulled the top and seat and went diving. Found that the light wire going to the shifter light had shorted in the harness to the solenoid wire from the neutral switch. BINGO !!! So if anyone tells you that the lights will crank their engine don't think they are crazy......just smile.....

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paul2748
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Location: Northeastern New Jersey

Re: 55 wiring issue

Post by paul2748 » Sun Mar 04, 2018 10:24 pm

Good to hear you found the problem. Electrical issues like that are had to find and like you did, are found only after making assumptions on what could be affecting the problem.
1956 Fiesta Red 312
1954 Ford Victoria 312
1948 Ford Convertible Street Rod 302

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