The Ford Barn

Ed Saniewski · 04-27-2025, 06:24 AM

There is a open coil resistor under the dash that is rusted and broken. The former owner has a jumper across the two ends. What is this for ? I found a wiring diagram that leads me to think it is for the ignition coil. Thanks

Jack E/NJ · 04-27-2025, 06:52 AM

Resistor limits current to points. So extends life of points & coil.

Bored&Stroked · 04-27-2025, 08:18 AM

It is for the coil - you'll definitely want one (or a suitable replacement) as it prevents over-voltage to the coil and burning your points.

Terry,OH · 04-28-2025, 06:55 AM

The resistor should have a cage around it and should measure 0.5 to 0.6 Ohm. Sounds as if the PO was running a different coil than the Ford. If so the resistor value may change from Fords.

Mac VP · 04-28-2025, 07:01 AM

The original resistor was designed to work with the original type Ford coil (which was mounted atop the Ford distributor). If the previous owner bypassed this resistor he may have changed to a remote mounted 6V coil, which would handle the full 6 volt input no problem. If the vehicle is again running with an original coil, you should replace the old damaged one with a new one. Part number is 18-12250. We and a few other vendors stock a high quality USA made part.

mcgarrett · 04-30-2025, 09:34 PM

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From what I've read about this, the resistor is especially important to keep from burning the points by reducing the voltage going to them to 4 volts.

Ed Saniewski · 05-01-2025, 05:12 AM

Thanks to all, I ordered one from third gen parts. The P O had jumped the resistor and caused the coil to overheat and explode.

04-27-2025, 06:24 AM	#1
Ed Saniewski Senior Member Join Date: May 2010 Location: Denville NJ Posts: 975	resistor under dash 1933 There is a open coil resistor under the dash that is rusted and broken. The former owner has a jumper across the two ends. What is this for ? I found a wiring diagram that leads me to think it is for the ignition coil. Thanks __________________ Model A Ford Club of New Jersey http://www.mafcnj.org Model A Pick Up Owners and Enthusiasts https://www.fordbarn.com/forum/group.php?groupid=5

04-27-2025, 06:52 AM	#2
Jack E/NJ Senior Member Join Date: May 2010 Posts: 2,260	Re: resistor under dash 1933 Resistor limits current to points. So extends life of points & coil.

04-27-2025, 08:18 AM	#3
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,723	Re: resistor under dash 1933 It is for the coil - you'll definitely want one (or a suitable replacement) as it prevents over-voltage to the coil and burning your points.

04-28-2025, 06:55 AM	#4
Terry,OH Senior Member Join Date: May 2010 Posts: 5,187	Re: resistor under dash 1933 The resistor should have a cage around it and should measure 0.5 to 0.6 Ohm. Sounds as if the PO was running a different coil than the Ford. If so the resistor value may change from Fords.

04-28-2025, 07:01 AM	#5
Mac VP Senior Member Join Date: May 2010 Location: Cincinnati, OH Posts: 1,430	Re: resistor under dash 1933 The original resistor was designed to work with the original type Ford coil (which was mounted atop the Ford distributor). If the previous owner bypassed this resistor he may have changed to a remote mounted 6V coil, which would handle the full 6 volt input no problem. If the vehicle is again running with an original coil, you should replace the old damaged one with a new one. Part number is 18-12250. We and a few other vendors stock a high quality USA made part. __________________ VANPELT SALES LLC Cincinnati, Ohio Office: 513-724-9486 www.vanpeltsales.com www.classictransmission.com

04-30-2025, 09:34 PM	#6
mcgarrett Senior Member Join Date: Dec 2013 Location: Corsicana, Texas Posts: 1,306	Re: resistor under dash 1933 Sponsored Links (Register now to hide all advertisements) From what I've read about this, the resistor is especially important to keep from burning the points by reducing the voltage going to them to 4 volts.

05-01-2025, 05:12 AM	#7
Ed Saniewski Senior Member Join Date: May 2010 Location: Denville NJ Posts: 975	Re: resistor under dash 1933 Thanks to all, I ordered one from third gen parts. The P O had jumped the resistor and caused the coil to overheat and explode. __________________ Model A Ford Club of New Jersey http://www.mafcnj.org Model A Pick Up Owners and Enthusiasts https://www.fordbarn.com/forum/group.php?groupid=5