The Ford Barn

Sal · 02-02-2016, 01:00 PM

I would like to thank you in advance for any advice you can render. On my '48 Ford I've got a problem where the tail and instrument lights come with the light switch in the park position. When I pull the knob to the head light position it loses tail and instrument lights, but the head lights will come on. The dimmer switch will also operate in both low and high beam. Can it be the light switch is no good?

Bolts · 02-02-2016, 01:22 PM

Sounds like the switch to me.
Remove it and test the functions with an ohm meter.
You can use the wiring diagram for that.
Sorry about the quality of the picture. Best I have. Others might be able to get you a better one.

Bolts · 02-02-2016, 01:34 PM

Possibly first you can run down the wiring to make sure it's wired correctly before removing the switch. Stock switch has a little slot for a small screwdriver to be inserted in so that the switch knob and shaft will come out so you can remove the nut and take the switch out. Not hard to do once you know how. Problem is the slot is on top and it's a little hard to reach.

flatheadmurre · 02-02-2016, 02:35 PM

Lots of different things that could be wrong but in or around the switch.
Wiring could be wrong but if it worked before thats not it.
Wornout or corroded contacts inside switch...spray with contactspray and wiggle the switch and se if you can excersise the switch to take away oxide.
Bad connection between rivets and contacts outside switch.
Check for loose rivets or signs of oxide.

cmbrucew · 02-02-2016, 04:06 PM

Sal
Some times light mysteries are the result of bad ground wires (tail light housings)
Bruce

Bruce Lancaster · 02-02-2016, 04:33 PM

Sponsored Links (Register now to hide all advertisements)

'48 Ford switches are very durable and generally fail just from dirt.
Remove the thing as noted above (this is a bit difficult the first time) and let it hang down on the wires so you can check wiring against the letters in plastic plate indicating proper locations.
The remove wiring, gently and carefully bend back the tabs, and remove plastic from metal body. Do this over a piece of cloth and lay the pieces inside out carefully...if you drop things you'll be in trouble fast. Swizzle the parts in thinner or whatever you use and brush away the decades of filth. Polish the brass contacts and carefully reassemble
with light grease on everything.
Bend tabs back carefully so the next overhaul won't be a problem for your grandchildren.

Sal · 02-02-2016, 07:30 PM

Thank You gentlemen for your replies. I will remove the switch test it and try to repair it.

koates · 02-02-2016, 08:22 PM

Hi there, maybe the tail and instrument light wires are connected on to the park light terminal on the switch. Some switches have the park lights go off when the headlights are on. Regards, Kevin.

Bolts · 02-03-2016, 09:13 AM

Quote:

Originally Posted by Sal

Thank You gentlemen for your replies. I will remove the switch test it and try to repair it.

Sal,
Sounds like the switch may be mis-wired. Did it ever work right?
There is a good wiring diagram here.

http://www.vanpeltsales.com/FH_web/F...1946-48car.jpg

If you feel it's necessary to remove the switch, REMEMBER TO DISCONNECT THE BATTERY FIRST.

I can't remember exactly, but when you insert the small screwdriver into the switch slot, I think the knob might need to be pushed in to the off position (possibly the other way around to full on position) and the knob rotated 90 degrees to remove the shaft. Not sure, but try rotating the knob without a lot of force before pulling too hard on the knob while lever is releasing the locking tab.

Sal · 02-03-2016, 12:57 PM

Yes, the switch was working correctly. When I was going to take it to a cruise night I found it had a tail light problem.

Bruce Lancaster · 02-03-2016, 03:31 PM

Another basic thing before you go to work: Unplug the taillights at the first bullet connectors about one foot from the lights and run a jumper wire to them to see if they light up. If they are good THEN tear down the switch and clean it.
You'll need a long wire to the battery hot post, of course, and this could be improvised from a household extension cord, with one person holding prong to battery and another making contact in back with a nail or something shoved into the female end of plug to allow touching the connector.

Sal · 02-03-2016, 05:31 PM

Tail and dash lights work in the park position.

Tim Ayers · 02-03-2016, 05:34 PM

Quote:

Originally Posted by cmbrucew

Sal
Some times light mysteries are the result of bad ground wires (tail light housings)
Bruce

I was going to say the same. Ground faults can drive you nuts!

TJ · 02-03-2016, 08:13 PM

I have found over the years that the 41-48 cars are infamous for having grounding problems. You can't hurt by adding extra grounds to the tailamps , headlamps, or anywhere else that could use a good ground.

Sal · 02-16-2016, 07:02 AM

I did what Bruce Lancaster suggested and took the switch out. I opened it up cleaned and polished the contacts re-assembled it. It works fine now. Thanks to all who replied.

Drbrown · 02-16-2016, 07:09 PM

Sal: Glad you found the problem. For what little this might be worth .... In my '47, the first notch of my dash switch (parking light position) turns on the front parking lights, instrument lights, key light and the tail/trunk/license plate lights" .... this agrees with the wiring diagrams I have.

When I move the dash switch to the second notch (head Light position) the front parking lights go out, the key light goes out, the head lights turn on, and the tail/trunk/license plate lights remain on.

An aside: As a safety feature, the brake lights ALWAYS work. They are "unfused" and wired separately and direct from the battery feed-side of the Circuit Breakers. The pillar and glove box (optional) are wired separately to the Circuit Breakers.

02-02-2016, 01:00 PM	#1
Sal Senior Member Join Date: May 2010 Posts: 218	Electric problem with tail lights I would like to thank you in advance for any advice you can render. On my '48 Ford I've got a problem where the tail and instrument lights come with the light switch in the park position. When I pull the knob to the head light position it loses tail and instrument lights, but the head lights will come on. The dimmer switch will also operate in both low and high beam. Can it be the light switch is no good?

02-02-2016, 02:35 PM	#4
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Electric problem with tail lights Lots of different things that could be wrong but in or around the switch. Wiring could be wrong but if it worked before thats not it. Wornout or corroded contacts inside switch...spray with contactspray and wiggle the switch and se if you can excersise the switch to take away oxide. Bad connection between rivets and contacts outside switch. Check for loose rivets or signs of oxide.

02-02-2016, 04:06 PM	#5
cmbrucew Senior Member Join Date: Dec 2010 Location: North of sandy ago, CA. Posts: 2,064	Re: Electric problem with tail lights Sal Some times light mysteries are the result of bad ground wires (tail light housings) Bruce __________________ Works good Lasts long time

02-02-2016, 04:33 PM	#6
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: Electric problem with tail lights Sponsored Links (Register now to hide all advertisements) '48 Ford switches are very durable and generally fail just from dirt. Remove the thing as noted above (this is a bit difficult the first time) and let it hang down on the wires so you can check wiring against the letters in plastic plate indicating proper locations. The remove wiring, gently and carefully bend back the tabs, and remove plastic from metal body. Do this over a piece of cloth and lay the pieces inside out carefully...if you drop things you'll be in trouble fast. Swizzle the parts in thinner or whatever you use and brush away the decades of filth. Polish the brass contacts and carefully reassemble with light grease on everything. Bend tabs back carefully so the next overhaul won't be a problem for your grandchildren.

02-02-2016, 07:30 PM	#7
Sal Senior Member Join Date: May 2010 Posts: 218	Re: Electric problem with tail lights Thank You gentlemen for your replies. I will remove the switch test it and try to repair it.

02-02-2016, 08:22 PM	#8
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,079	Re: Electric problem with tail lights Hi there, maybe the tail and instrument light wires are connected on to the park light terminal on the switch. Some switches have the park lights go off when the headlights are on. Regards, Kevin.

02-03-2016, 12:57 PM	#10
Sal Senior Member Join Date: May 2010 Posts: 218	Re: Electric problem with tail lights Yes, the switch was working correctly. When I was going to take it to a cruise night I found it had a tail light problem.

02-03-2016, 03:31 PM	#11
Bruce Lancaster Member Emeritus Join Date: May 2010 Location: Madison, NJ Posts: 5,230	Re: Electric problem with tail lights Another basic thing before you go to work: Unplug the taillights at the first bullet connectors about one foot from the lights and run a jumper wire to them to see if they light up. If they are good THEN tear down the switch and clean it. You'll need a long wire to the battery hot post, of course, and this could be improvised from a household extension cord, with one person holding prong to battery and another making contact in back with a nail or something shoved into the female end of plug to allow touching the connector.

02-03-2016, 05:31 PM	#12
Sal Senior Member Join Date: May 2010 Posts: 218	Re: Electric problem with tail lights Tail and dash lights work in the park position.

02-03-2016, 08:13 PM	#14
TJ Senior Member Join Date: May 2010 Location: Napa,California Posts: 6,037	Re: Electric problem with tail lights I have found over the years that the 41-48 cars are infamous for having grounding problems. You can't hurt by adding extra grounds to the tailamps , headlamps, or anywhere else that could use a good ground.

02-16-2016, 07:02 AM	#15
Sal Senior Member Join Date: May 2010 Posts: 218	Re: Electric problem with tail lights I did what Bruce Lancaster suggested and took the switch out. I opened it up cleaned and polished the contacts re-assembled it. It works fine now. Thanks to all who replied.

02-16-2016, 07:09 PM	#16
Drbrown Senior Member Join Date: Oct 2013 Location: Glens Falls NY Posts: 1,267	Re: Electric problem with tail lights Sal: Glad you found the problem. For what little this might be worth .... In my '47, the first notch of my dash switch (parking light position) turns on the front parking lights, instrument lights, key light and the tail/trunk/license plate lights" .... this agrees with the wiring diagrams I have. When I move the dash switch to the second notch (head Light position) the front parking lights go out, the key light goes out, the head lights turn on, and the tail/trunk/license plate lights remain on. An aside: As a safety feature, the brake lights ALWAYS work. They are "unfused" and wired separately and direct from the battery feed-side of the Circuit Breakers. The pillar and glove box (optional) are wired separately to the Circuit Breakers.