The Ford Barn

Woodie1 · 05-23-2020, 12:18 PM

I have an old repro ignition cable that has been on the car for over 35 years. It was new when installed & the car doesn't have a lot of miles on it. For the last 2 years I've been chasing a battery drain problem. I charged the battery a couple of days ago & came out a couple hours later to start the car & it was dead. I charged the battery again & when touching the negative cable to the starter switch I saw small sparks. I traced the ground back to the ignition switch connection for the coil. I would think that the stud on the switch head should not be grounded whether the switch is closed or popped open for on position. When pushed in, I get a ground on the stud on the cable head. I'm thinking this is not right. Does it sound like I'm on the right track here? I also found the coil hot to touch.Thanks.

rotorwrench · 05-23-2020, 01:05 PM

Sometimes points are open and sometimes they are closed so you never know whether there will be a ground path all the way to ground for the coil after the engine is shut down. The coil has power available to it at all times since the Electrolock type switches control the breaker/ground side of the coil. This is assuming you have an Electrolock type reproduction. They did make these for quite a while but they are no longer available. I just don't know if a person can repair one of the reproductions or not. Folks repair the original types all the time.

Woodie1 · 05-23-2020, 01:12 PM

I'm not sure of the maker. I originally bought them from Specialized in Texas. I did make sure the points were open when checking the ground. I compared it to another "A" we have & I did not get a spark when fastening the battery cable to the starter switch. I'm just asking if my notion that the problem is the ignition switch sounds correct. I don't have a spare to try. I will need to order something.

shew01 · 05-23-2020, 05:27 PM

Quote:

Originally Posted by Woodie1

I'm not sure of the maker. I originally bought them from Specialized in Texas. I did make sure the points were open when checking the ground. I compared it to another "A" we have & I did not get a spark when fastening the battery cable to the starter switch. I'm just asking if my notion that the problem is the ignition switch sounds correct. I don't have a spare to try. I will need to order something.

I recently had a similar issue. My rebuilt original pop out switch had 6 volts on the moving point arm when turned “on.” When turned “off,” the moving point arm still had .27 volts on it. That was enough to keep the coil warm and drain the battery.

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rotorwrench · 05-24-2020, 10:00 AM

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I generally disconnect the ground side of the battery first. This way there is no arcing. When you attach the power side of the battery when the ground is already attached, there is still an in rush when you connect and it can cause arcing even if no loads are turned on. Most shop manuals will recommend ground disconnect first and reconnect last. Wiring has resistance even though the runs are short so this is where the in rush's source comes from.

If you have a digital multi-meter, you can disconnect the battery ground and connect the multi-meter in to bridge the gap between the battery ground post and the cable terminal. Set the meter up to read amps in the area of around 10-amps max. The meter will show what ever draw on the system that may be present. If there is no indication or a Zero indication then there is no short. If it shows a reading at all then there is a short some where. Disconnect each circuit until the meter reads zero and you will find the shorted circuit. Since the coil & breaker circuit is suspect, the the power side of the coil can be disconnected first to see if that's the problem. If that isn't it, keep disconnecting circuits till you find the problem circuit. Disconnect each circuit to be tested from its power source. The coil and brake light circuits are the most common problem sources but any circuits can have a short. Luckily there aren't too many circuits in the design so it shouldn't take too long to find it.

05-23-2020, 12:18 PM	#1
Woodie1 Senior Member Join Date: Mar 2011 Location: W. Mich. Posts: 471	Ignition cable I have an old repro ignition cable that has been on the car for over 35 years. It was new when installed & the car doesn't have a lot of miles on it. For the last 2 years I've been chasing a battery drain problem. I charged the battery a couple of days ago & came out a couple hours later to start the car & it was dead. I charged the battery again & when touching the negative cable to the starter switch I saw small sparks. I traced the ground back to the ignition switch connection for the coil. I would think that the stud on the switch head should not be grounded whether the switch is closed or popped open for on position. When pushed in, I get a ground on the stud on the cable head. I'm thinking this is not right. Does it sound like I'm on the right track here? I also found the coil hot to touch.Thanks.

05-23-2020, 01:05 PM	#2
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: Ignition cable Sometimes points are open and sometimes they are closed so you never know whether there will be a ground path all the way to ground for the coil after the engine is shut down. The coil has power available to it at all times since the Electrolock type switches control the breaker/ground side of the coil. This is assuming you have an Electrolock type reproduction. They did make these for quite a while but they are no longer available. I just don't know if a person can repair one of the reproductions or not. Folks repair the original types all the time.

05-23-2020, 01:12 PM	#3
Woodie1 Senior Member Join Date: Mar 2011 Location: W. Mich. Posts: 471	Re: Ignition cable I'm not sure of the maker. I originally bought them from Specialized in Texas. I did make sure the points were open when checking the ground. I compared it to another "A" we have & I did not get a spark when fastening the battery cable to the starter switch. I'm just asking if my notion that the problem is the ignition switch sounds correct. I don't have a spare to try. I will need to order something.

05-24-2020, 10:00 AM	#5
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: Ignition cable Sponsored Links (Register now to hide all advertisements) I generally disconnect the ground side of the battery first. This way there is no arcing. When you attach the power side of the battery when the ground is already attached, there is still an in rush when you connect and it can cause arcing even if no loads are turned on. Most shop manuals will recommend ground disconnect first and reconnect last. Wiring has resistance even though the runs are short so this is where the in rush's source comes from. If you have a digital multi-meter, you can disconnect the battery ground and connect the multi-meter in to bridge the gap between the battery ground post and the cable terminal. Set the meter up to read amps in the area of around 10-amps max. The meter will show what ever draw on the system that may be present. If there is no indication or a Zero indication then there is no short. If it shows a reading at all then there is a short some where. Disconnect each circuit until the meter reads zero and you will find the shorted circuit. Since the coil & breaker circuit is suspect, the the power side of the coil can be disconnected first to see if that's the problem. If that isn't it, keep disconnecting circuits till you find the problem circuit. Disconnect each circuit to be tested from its power source. The coil and brake light circuits are the most common problem sources but any circuits can have a short. Luckily there aren't too many circuits in the design so it shouldn't take too long to find it. Last edited by rotorwrench; 05-24-2020 at 10:06 AM.