The Ford Barn

Al 29Tudor · 12-06-2020, 06:45 AM

Good morning All,
I'd like to know how to set up a load test something like when a battery is tested.
I went crazy for months trying to figure why my car wouldn't start. Once in a while it wouls start right up just as i lifted off the start button. It was as if there was not enough juice for the ingnition while it was cranknig. Finall i found it was the ignition switch which was warm to thetouch after running for a while.
I think if an electrical load could be applied along with the multi meter it would show a dropin voltage while testing the ignition switch.
Thanks for your thoughts.
Al

alexiskai · 12-06-2020, 08:37 AM

Just to be clear, your question is: Is there a way to use a multimeter to test whether a given component (ignition, lights, horn, brake light) is shorting/grounding when activated? In other words the component itself is "working" but it's sucking power out of the circuit when it's on. Is that what you're asking?

Mister Moose · 12-06-2020, 09:08 AM

A simple ohm reading with a decent meter will tell you what you want to know. The problem is that many times electrical issues are intermittent - you won't find it until you test it on a day it's acting up. That can slow down the detective work to find the problem.

nkaminar · 12-06-2020, 09:13 AM

I found that a voltmeter replacement or in addition to the ammeter on my car was more helpful. I can see the battery voltage with no load, when running the starting motor, with the ignition or lights on, or when the battery is being charged. As far as testing something like the ignition switch, just measure the voltage across it when operating. That will tell you a lot about whether it is bad or not. If you know the current you can calculate the resistance using Ohm's law.

I found a bad battery using the installed voltmeter. It was only 10 years old.

Badpuppy · 12-06-2020, 10:16 AM

Quote:

Originally Posted by Al 29Tudor

Good morning All,
I think if an electrical load could be applied along with the multi meter it would show a dropin voltage while testing the ignition switch.
Thanks for your thoughts.
Al

Measure voltage across the coil with switch on and points closed; it should read full battery voltage. If any less, the ignition switch is dropping the balance, meaning it has resistance greater than zero.

Mechanical contacts arc and weaken with time, requiring an occasional Fonzie bump to make them work properly.

redmodelt · 12-06-2020, 11:24 AM

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"requiring an occasional Fonzie bump" LOL Thanks, nice to have a chuckle early in the day!

Might also clean the terminals/grounds and do a load test on the battery. Just checking it's voltage may not tell the whole story.

Bruce of MN · 12-07-2020, 06:14 AM

I recently discovered that my car's starter cable was smaller than a #4 AWG, so make sure yours is a #1 AWG at least.

12-06-2020, 08:37 AM	#2
alexiskai Senior Member Join Date: Apr 2018 Location: Mebane NC Posts: 2,354	Re: 6 volt load test Just to be clear, your question is: Is there a way to use a multimeter to test whether a given component (ignition, lights, horn, brake light) is shorting/grounding when activated? In other words the component itself is "working" but it's sucking power out of the circuit when it's on. Is that what you're asking?

12-06-2020, 09:08 AM	#3
Mister Moose Senior Member Join Date: Jun 2020 Location: Hartford area, CT Posts: 374	Re: 6 volt load test A simple ohm reading with a decent meter will tell you what you want to know. The problem is that many times electrical issues are intermittent - you won't find it until you test it on a day it's acting up. That can slow down the detective work to find the problem.

12-06-2020, 11:24 AM	#6
redmodelt Senior Member Join Date: May 2010 Location: Portland OR Posts: 6,340	Re: 6 volt load test Sponsored Links (Register now to hide all advertisements) "requiring an occasional Fonzie bump" LOL Thanks, nice to have a chuckle early in the day! Might also clean the terminals/grounds and do a load test on the battery. Just checking it's voltage may not tell the whole story. __________________ I know the voices aren't real but damn they have some good ideas!

12-07-2020, 06:14 AM	#7
Bruce of MN Senior Member Join Date: May 2010 Location: VA Posts: 1,410	Re: 6 volt load test I recently discovered that my car's starter cable was smaller than a #4 AWG, so make sure yours is a #1 AWG at least.

12-06-2020, 06:45 AM	#1
Al 29Tudor Senior Member Join Date: Jul 2012 Location: Venice, FL Posts: 648	6 volt load test Good morning All, I'd like to know how to set up a load test something like when a battery is tested. I went crazy for months trying to figure why my car wouldn't start. Once in a while it wouls start right up just as i lifted off the start button. It was as if there was not enough juice for the ingnition while it was cranknig. Finall i found it was the ignition switch which was warm to thetouch after running for a while. I think if an electrical load could be applied along with the multi meter it would show a dropin voltage while testing the ignition switch. Thanks for your thoughts. Al

12-06-2020, 09:13 AM	#4
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: 6 volt load test I found that a voltmeter replacement or in addition to the ammeter on my car was more helpful. I can see the battery voltage with no load, when running the starting motor, with the ignition or lights on, or when the battery is being charged. As far as testing something like the ignition switch, just measure the voltage across it when operating. That will tell you a lot about whether it is bad or not. If you know the current you can calculate the resistance using Ohm's law. I found a bad battery using the installed voltmeter. It was only 10 years old. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.