The Ford Barn

40ford · 07-03-2019, 08:32 AM

I can't understand why I am getting low voltage at coil?I am getting 1.58 with resistor I have mounted now.The resistor I got from Carpenters gave me a 1.98 volt reading.The car cranks and runs ok,but I thought you needed at least 3 volts for good fire?I got over 6 volts going to the resistor so I figured the switch block was ok.This is on a stock 40 with 6 volt system.

JSeery · 07-03-2019, 08:35 AM

Are you sure your readings are correct? Have you tried a different meter? I would start by verifying the readings.

40ford · 07-03-2019, 11:11 AM

Yes,I am sure that reading is correct.I got another resistor to try.Is there a way to check a resistor before installing it in car?Does the reading have anything to do if points are closed or open?Heck I am lost here?

JSeery · 07-03-2019, 12:07 PM

Yes, the points have to be closed. Yes you can check the resistor with the ohms settings on your meter.

flatheadmurre · 07-03-2019, 12:10 PM

If the coil is a different resistence from what it should be you get this kind of errors...
Voltage drop over the resistor is depending on how much current flows through it...if the coil draws less amps then it should reading over resistor goes down to...

JSeery · 07-03-2019, 12:37 PM

Sponsored Links (Register now to hide all advertisements)

Good point, might want to determine the coil resistance first.

G.M. · 07-03-2019, 01:26 PM

It will not start with 2.0 volts. The starter pulls
the voltage down even lower. You are not reading
correctly or meter is in wrong scale. G.M.

07-03-2019, 08:32 AM	#1
40ford Senior Member Join Date: May 2010 Location: Cherryville,N.C. Posts: 535	Low Coil Voltage: I can't understand why I am getting low voltage at coil?I am getting 1.58 with resistor I have mounted now.The resistor I got from Carpenters gave me a 1.98 volt reading.The car cranks and runs ok,but I thought you needed at least 3 volts for good fire?I got over 6 volts going to the resistor so I figured the switch block was ok.This is on a stock 40 with 6 volt system.

07-03-2019, 08:35 AM	#2
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Low Coil Voltage: Are you sure your readings are correct? Have you tried a different meter? I would start by verifying the readings.

07-03-2019, 11:11 AM	#3
40ford Senior Member Join Date: May 2010 Location: Cherryville,N.C. Posts: 535	Re: Low Coil Voltage: Yes,I am sure that reading is correct.I got another resistor to try.Is there a way to check a resistor before installing it in car?Does the reading have anything to do if points are closed or open?Heck I am lost here?

07-03-2019, 12:07 PM	#4
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Low Coil Voltage: Yes, the points have to be closed. Yes you can check the resistor with the ohms settings on your meter.

07-03-2019, 12:10 PM	#5
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Low Coil Voltage: If the coil is a different resistence from what it should be you get this kind of errors... Voltage drop over the resistor is depending on how much current flows through it...if the coil draws less amps then it should reading over resistor goes down to...

07-03-2019, 12:37 PM	#6
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Low Coil Voltage: Sponsored Links (Register now to hide all advertisements) Good point, might want to determine the coil resistance first.

07-03-2019, 01:26 PM	#7
G.M. Senior Member Join Date: May 2010 Location: Florida and Penna. Posts: 4,471	Re: Low Coil Voltage: It will not start with 2.0 volts. The starter pulls the voltage down even lower. You are not reading correctly or meter is in wrong scale. G.M. __________________ www.fordcollector.com