Electrical Issue with Ignition Switch

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Model T Ford Forum: Forum 2014: Electrical Issue with Ignition Switch
Top of pagePrevious messageNext messageBottom of page Link to this message  By Josh Lauener on Monday, November 10, 2014 - 04:35 pm:

I have an electrical short somewhere and I'm hoping someone can help me out--in layman's terms. The car runs fine when the ignition switch/ammeter plate is not screwed into the dash, but once I screw it in and plug in the cutoff switch, two wires start smoking. They are the wires that run from the starter switch in the floor to the terminal block, and from the terminal block to the ignition switch. The wire itself is not the problem, and yesterday, after rewiring these two wires, I was running the car (thinking I had the problem fixed) and noticed a spark out of the area near the bottom right switch plate screw, but other than that it ran fine.

I then let the car sit for a bit thinking I had the problem solved, and when I plugged in the cutoff switch again to try to run it again the same two wires began smoking badly.

If you know what the problem is, I thank you in advance for the help. Please let me know if you need any more information.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Monday, November 10, 2014 - 06:42 pm:

I honestly don't know what you mean by a cut off switch but if you saw sparking at a mounting screw for the ignition switch/amp meter plate without it hooked up you probably have a short internally in the switch. The sparking indicates momentary grounding. Not enough to smoke the wires but it's there any way. Obviously the switch should not be shorting to the case. When it's out it's OK but when you mount it in place it completes the circuit to ground. With the plate out hook up a test light from the plate to the dash. If it lights up you've located the short. Another thing, with the plate mounted in the dash hooking up that cut off switch also seems to complete the circuit to ground frying the wires.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Josh Lauener on Monday, November 10, 2014 - 07:57 pm:

Sorry, it's a piece I installed that requires a plastic key to be inserted so there is power to the car. When plastic key is not in place, there is no power to the car. I put it there as an easy way to prevent constant drain on the battery while car is sitting in garage.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Monday, November 10, 2014 - 08:16 pm:

I'd like to know where the cut-off is wired to. You stated you saw sparking at a plate mounting screw with the cut-off disconnected. If it cuts power to the ignition switch does it also cut power to the amp meter? (I don't have a T wiring diag. in front of me so I'm kind of guessing).


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Monday, November 10, 2014 - 08:35 pm:

OK. Got one. One of your cooking wires from the starter sw. goes thru the terminal board (yellow #3) thru the amp meter and then to the ign switch. That whole circuit is powered constantly indicating the amp meter or the ign. switch might be shorted internally. It's shorting out and powering the metal mounting plate which is why you see sparks from the mounting screws when you mount the plate to the dash. With the plate unmounted hook up a test lamp to the plate and the dash. Make sure you have good connections. If the lamp lights (it might be dim) disconnect the wire on the out put side of the amp meter. Not the battery/feed side the one that goes to the ign. switch. If the light stays on it's the meter shorted internally. If it goes out it's the switch since it's not getting power any more.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Wetherbee on Tuesday, November 11, 2014 - 12:36 pm:

I had a similar issue - what it turned out to be was the plate that the key tumbler goes into was worn out allowing the tumbler to touch one of the leads of the contact mounted there.

I wound up super-glueing a shim in the slot to tighten it to the tumbler.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Tuesday, November 11, 2014 - 01:22 pm:

Either an internal connection inside the switch to the switch plate, or one of the wires on the outside is in contact with the plate. Possibly the wire only touches the plate when in the position it is in when mounted.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By G.R.Cheshire on Tuesday, November 11, 2014 - 01:28 pm:

Josh; maybe you have the cut out switch (the new one you installed)Grounded try insulating it from the body so there is no contact with the body of the car.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Wednesday, November 12, 2014 - 07:31 am:

Josh,

Have you gotten it figured out yet? Let me know if you would like for me to come take a look at it.

Was that you at Danny Harden's place Saturday? I saw a Roadster leaving, but wasn't sure if it was you. I was busy running steam engines and did not get a chance to wander around, so I don't know who all came.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Josh Lauener on Wednesday, November 12, 2014 - 07:48 am:

Thanks everyone for all your advice. I am grateful to know that my problem seems to lie in the switch/amp meter and not in my wiring. I'll try some things this weekend.

Hal, I was not there because I have been dealing with this issue since the last time we were emailing, I'm just finally getting around to working on it. I'm going to pull the part out this weekend and poke around and see what I can figure out. I'll let you know if I need any help.

Thanks again everyone!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Josh Lauener on Sunday, November 16, 2014 - 09:59 am:

If anyone else reads this, I took apart the amp meter switch and realized I had the rectangular insulation piece in the wrong spot. I moved it inside of the back plate and it now works fine. Another case where I should have taken pictures of the before to help me with the after.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Sunday, November 16, 2014 - 10:16 am:

Glad you got it figured out.


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