The Ford Barn

bikemaniac · 07-07-2014, 06:34 PM

Hi,
I am on my way doing all the electrical work on my 1930 tudor which still has the original generator and cut out relay. When the car is off and I hook up the final heavy gauge cable to the battery, it sparks a little when connecting. At the same time the ammeter reading goes to a full discharge reading. I can turn on the lights and use the horn just fine in this "mode", but I have a bad feeling. If I disconnect the cables from the cut out relay to effectively bypass the cut out relay (and connect them with a screw and a nut) there is no spark when hooking up the final cable and the ammeter stays put at 0. I can now turn on the lights with a normal ammeter discharge reading. Is my cut out relay observation indicating a faulty relay, can it be repaired ... or is it just normal? Can I use a multimeter to test the cut out relay in some way?
Lucas

Tom Wesenberg · 07-07-2014, 07:10 PM

Yes, the trouble seems to be in the cutout. Remove it and measure the INPUT to case in ohms. Original is about 50 ohms, while repros have less wire and measure about 20 to 30 ohms. Now measure the output to case and to input. It should show OPEN in both cases.

Sometimes a person uses a screw that is too long and touches the coils and shorts out the cutout. Also be sure the insulating washers are in place on both terminals of the cutout. The thick washer is used on the output.

Mitch//pa · 07-07-2014, 08:34 PM

a simple check with a test light engine off if it lights on the generator side of the cut out it is stuck and causing a draw on the battery.

bikemaniac · 07-08-2014, 12:57 AM

When measuring my relay I seem to have almost 0 Ohms everywhere. When inspecting the relay, the input and output holes/threads it seems there is no insulation so the body of the relay is touching everywhere. It looks like the body/house is pressed on top with a tight fit effectively making contact everywhere.

Tom Wesenberg · 07-08-2014, 05:29 AM

Sponsored Links (Register now to hide all advertisements)

Original cutouts have the cover spotwelded in two place on the bottom edge. Repro cutouts have the covers held on by two bends in the bottom edge. Both need an insulater between the terminal and the cover, both on the inside and outside of the cover.

07-07-2014, 06:34 PM	#1
bikemaniac Senior Member Join Date: Aug 2013 Location: Copenhagen Posts: 177	Cut out relay troubleshooting? Hi, I am on my way doing all the electrical work on my 1930 tudor which still has the original generator and cut out relay. When the car is off and I hook up the final heavy gauge cable to the battery, it sparks a little when connecting. At the same time the ammeter reading goes to a full discharge reading. I can turn on the lights and use the horn just fine in this "mode", but I have a bad feeling. If I disconnect the cables from the cut out relay to effectively bypass the cut out relay (and connect them with a screw and a nut) there is no spark when hooking up the final cable and the ammeter stays put at 0. I can now turn on the lights with a normal ammeter discharge reading. Is my cut out relay observation indicating a faulty relay, can it be repaired ... or is it just normal? Can I use a multimeter to test the cut out relay in some way? Lucas

07-07-2014, 07:10 PM	#2
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Cut out relay troubleshooting? Yes, the trouble seems to be in the cutout. Remove it and measure the INPUT to case in ohms. Original is about 50 ohms, while repros have less wire and measure about 20 to 30 ohms. Now measure the output to case and to input. It should show OPEN in both cases. Sometimes a person uses a screw that is too long and touches the coils and shorts out the cutout. Also be sure the insulating washers are in place on both terminals of the cutout. The thick washer is used on the output.

07-07-2014, 08:34 PM	#3
Mitch//pa BANNED Join Date: May 2010 Location: Bucks County, PA Posts: 11,454	Re: Cut out relay troubleshooting? a simple check with a test light engine off if it lights on the generator side of the cut out it is stuck and causing a draw on the battery.

07-08-2014, 12:57 AM	#4
bikemaniac Senior Member Join Date: Aug 2013 Location: Copenhagen Posts: 177	Re: Cut out relay troubleshooting? When measuring my relay I seem to have almost 0 Ohms everywhere. When inspecting the relay, the input and output holes/threads it seems there is no insulation so the body of the relay is touching everywhere. It looks like the body/house is pressed on top with a tight fit effectively making contact everywhere.

07-08-2014, 05:29 AM	#5
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Re: Cut out relay troubleshooting? Sponsored Links (Register now to hide all advertisements) Original cutouts have the cover spotwelded in two place on the bottom edge. Repro cutouts have the covers held on by two bends in the bottom edge. Both need an insulater between the terminal and the cover, both on the inside and outside of the cover.