Go Back   The Ford Barn > General Discussion > Early V8 (1932-53)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 11-30-2014, 02:04 AM   #1
Joeyv
Junior Member
 
Join Date: Nov 2010
Location: San Diego
Posts: 26
Default 41 Mercury - Tail lights not working!

I'm hoping someone has the know-how that can help me with a problem I am having with my 41 Mercury's non-functioning tail lights. The car is stock, with a 6 volt system, with the exception of after market turn signals. The turn signals use the fender mounted parking lights in the front, and bumper mounted turn signal lights that were added to the rear.

The headlights work properly. When I tested one of the rear bulb sockets, there was no current at the tail light bulbs, nor at the wires at the back end of the car.

I checked for current at the light switch with the knob pushed in; the light switch's B terminal ( with the "3RY" wire, which connects to the circuit breaker's terminal H) is always hot. No other terminal on the light switch is hot with the knob pushed in. When light switch is pulled out the light switch's H terminal ( the "4YB" wire, which connects to the headlight foot switch) is hot along with terminal B. No other terminal on the light switch gets hot.

On the circuit breaker, terminals B & H are hot. Terminal A on the circuit breaker does not get hot, and I'm thinking that it should be hot, and that is my problem...but I don't know.

I found out my tail lights weren't working when I went to a car run at night, the first night run in a long time. My headlights were dim and flickering, and the tail lights were out. I put in a new headlight switch, and replaced the short pigtails from the light switch to the wire harness connections under the dash. The pigtails that i replaced were pretty worn/falling apart and taped up. The rest of the under dash wiring looks pretty good. After that, the headlights worked fine, but still no tail lights.

I attached (hopefully) pictures of the components I'm working with.

I have rudimentary electric system diagnostics skills so any suggestions where to test next would be greatly appreciated....thanks!
Attached Images
File Type: jpg Lightswitch1.jpg (67.3 KB, 36 views)
File Type: jpg Pigtails.jpg (42.7 KB, 35 views)
File Type: jpg Circuitbreaker.jpg (43.7 KB, 40 views)

Last edited by Joeyv; 11-30-2014 at 02:45 AM.
Joeyv is offline   Reply With Quote
Old 11-30-2014, 04:29 AM   #2
Mart
Senior Member
 
Mart's Avatar
 
Join Date: May 2010
Location: Solihull, England.
Posts: 7,227
Default Re: 41 Mercury - Tail lights not working!

Trace the route by which the tail lights get their power. trace every point along that route for the wire being live ("hot") with the switch on. When you get to where it suddenly is no longer live you have found the problem area and can investigate.

Do you know which terminal on the switch is supposed to feed the rear lights? That would help as a start.

Don't rule out that both rear bulbs may be blown. (You do say that neither rear light socket is live though).

Mart.
Mart is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 11-30-2014, 07:33 AM   #3
Steves46
Senior Member
 
Steves46's Avatar
 
Join Date: May 2010
Location: Lithia, FL
Posts: 970
Default Re: 41 Mercury - Tail lights not working!

Although this is not directly related to your tail light issue, I noticed you have two wires connected to a single terminal under the ballast resistor. Generally, the wire that connects directly to the ignition coil should be connected to the left terminal; the right terminal connects to the wire from the ignition switch. (It may be different for the 41s-this is the way mine is set-up on the 46).
__________________
If it aint broke, don't fix it!
Steves46 is offline   Reply With Quote
Old 11-30-2014, 08:14 AM   #4
funrunr
Senior Member
 
funrunr's Avatar
 
Join Date: May 2010
Location: Belleville,MI
Posts: 1,389
Default Re: 41 Mercury - Tail lights not working!

Check your tailight wire with an OHM meter- continuity tester, you can use a known good long wire to connect to one end of the tailight wire and bring it to the opposite end. Now touch the two ends with the meter one on each. This should make a beeping sound. The battery or ignition should not be on for this test. This will tell you if you have a "break" in the wire. Van Pelts website has drawings for your wiring and you can check them accordingly. Good luck and Let us know, hope this helps.
__________________
Thank God
this is only a hobby!
funrunr is offline   Reply With Quote
Old 11-30-2014, 10:06 AM   #5
TJ
Senior Member
 
TJ's Avatar
 
Join Date: May 2010
Location: Napa,California
Posts: 4,873
Default Re: 41 Mercury - Tail lights not working!

Check the wires at the left rear corner of the frame where the tailamp wires join together for the crossover harness. With the light switch on see if you have "fire" in the main tailamp wire. If you had wiring under the dash that was frayed and losing insulation, I suspect the wires under the car are probably a lot worse. If the car has the original harness the wiring is 75 years old. You are long overdue for new wiring and have the potential for a wiring fire.
TJ is offline   Reply With Quote
Old 11-30-2014, 11:13 AM   #6
Joeyv
Junior Member
 
Join Date: Nov 2010
Location: San Diego
Posts: 26
Default Re: 41 Mercury - Tail lights not working!

Sponsored Links (Register now to hide all advertisements)
Guys, thanks for the advice. I'll be getting out to my car again tomorrow and I will check on the items that you suggested. My concern is there does not seem to be any power at the light switch on the terminals that should be feeding the taillights. I was thinking I might have a bad Circuit breaker because all the terminals on the circuit breaker are not hot. Thanks again, I'll keep you posted on my progress.
Joeyv is offline   Reply With Quote
Old 12-04-2014, 02:16 PM   #7
Joeyv
Junior Member
 
Join Date: Nov 2010
Location: San Diego
Posts: 26
Default Re: 41 Mercury - Tail lights not working!

I have not solved the problem yet, but I did find that the wiring harness segment going to the back of the car was sitting very close to the exhaust, while it is intact, it is cooked "crispy". I order that segment of harness from YNZ and should have it in a couple of weeks. I'll let you all know how it goes. Thanks for the advice!
Attached Images
File Type: jpg IMG_0032.JPG (75.6 KB, 13 views)
Joeyv is offline   Reply With Quote
Old 12-04-2014, 04:08 PM   #8
rotorwrench
Senior Member
 
rotorwrench's Avatar
 
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 12,585
Default Re: 41 Mercury - Tail lights not working!

I was looking at the diagram and noticed than there are two wires connecting the light switch to the circuit breaker terminals. One is red/yellow and the other is yellow/red. Both of those should be hot at the switch but they don't connect to the same terminal on the breaker assembly. One is likely for head lamps and the other for the stop & tail lamps. If there is a short in any of the circuits on the breaker terminal that the tail lamps connect too, there may be a short in the brake lights or the dome lamp as well as the tail lights that could be causing the breaker to trip. If the breaker trips, it generally will reset after it cools only to trip again as soon as it gets hot from the short. If it has gone bad then it won't reset after it cools any more. You may have two problems there is basically what I'm implying. You will have to disconnect all three wires from that breaker terminal and see it it resets. If it does then you will have to reconnect one wire at a time to see which one is causing the short.
rotorwrench is online now   Reply With Quote
Old 12-04-2014, 05:56 PM   #9
supereal
Senior Member
 
supereal's Avatar
 
Join Date: Jul 2014
Location: Iowa
Posts: 1,499
Default Re: 41 Mercury - Tail lights not working!

The majority of lighting failure is caused by the "bullet" connectors. These were used for factory assembly. Follow the wire until you find a bullet connector. It is a rubber covered tube with wires into each end. Usually the rubber has hardened and fallen off, and will cause a short of it touches any part of the body and frame. During restoration we remove the connectors and solder the wires together, then use heat shrink tubing to cover the splice. For the purists, it looks like the original. The repro connectors are mostly plastic covered, and are as troublesome as the old originals.
supereal is offline   Reply With Quote
Old 12-04-2014, 06:34 PM   #10
Joeyv
Junior Member
 
Join Date: Nov 2010
Location: San Diego
Posts: 26
Default Re: 41 Mercury - Tail lights not working!

Rotorwrench, I agree with you. It is hard to tell the colors of the wires on the circuit breaker when I look at them under the dash, but I do know that the functioning headlights are the sole wire (R/Y) attached to the center Hot terminal (the “H” terminal) of the Circuit breaker. The Circuit breaker’s left terminal (the “B” terminal) is also hot. The “B” terminal also has one wire that connects to the ammeter & also several wires (I can’t tell their color, even from the photos) that are all connected to a single connector on that left hand circuit breaker terminal. According to the wiring diagrams in my Mercury shop manual the Y/R taillight wire should be connected to the hot “B” terminal (this makes no sense since there is no power to the tail light terminal on the light switch). According to the diagram that came with the new pigtail wires I just put on (part 11A-1165K) that connect the new light switch to the existing wire harness, the tail light wire is connected to the “A” terminal, which has no power to it. That makes sense in this situation. In the photo I attached in my earlier post, as I now look at it enlarged on my computer, it looks like the wire attached to dead circuit breaker terminal “A” is Yellow with Red. It is much easier to see in the enlarged photo, than it is looking at the wire under the dash! I’m thinking that the diagram that came with the pigtail wires is correct, that the tail lights connect to terminal “A”. I did disconnect the wire to terminal “A”, and the circuit breaker did not reset. Maybe I did not wait long enough. I’ll be testing it again and will post the results, but right now it looks like your assessment is correct, there are 2 problems, a short in the (fried) wires going to the back of the car and a non-functioning circuit breaker.
As a side note, I did disconnect the headlight wire off of the light switch and connected the tail light wire in its place. Still no tail lights, and the Circuit breaker starting clicking (the wire was quickly removed). That confirms, in a not very elegant manner, the short in the taillight circuit.
Supereal, Thanks for the recommendation, I will do that!
Thanks guys for the assist in this not-to-interesting problem.
Joeyv is offline   Reply With Quote
Old 12-05-2014, 01:03 PM   #11
TomO
Senior Member
 
Join Date: May 2010
Posts: 356
Default Re: 41 Mercury - Tail lights not working!

I can't tell the colors of all of the wires in your photo, but the tail light and license light are fed from the black wire. The instrument panel lights are also connected to the same terminal as the tail lights.

Looking at the wiring diagram and the photo of the switch, you should have the power coming into the right hand side of the switch from the circuit breaker and going out to the lights on the left hand side of the switch. Both the red wire and the yellow wire with the red tracer come from the circuit breaker.

Your tail lights and instrument panel lights should get power from the center terminal of the left side of the switch. This terminal should have power when the switch is in the parking light and head light position.

The terminal nearest the knob should have the wire for the parking lights and the one furthest from the knob should have the head light power going to the dimmer switch.

You can use your ohm meter to check out the switch operation.
__________________
TomO
TomO is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 09:37 AM.