Front turn signal problem on 1956 Thunderbird

zuburg

zuburg

Senior Member
Symptoms:
When you turn on either turn signal, both turn-signal indicators on the dashboard flash.
* Neither front turn-signal light works.
* Both rear turn signals work.

Both relays on the front inner fenders were replaced recently to solve a horn problem. I understand those relays control both the horn and headlights. Do they have anything to do with front turn signals?

What things should I do to correct (of course, sorted by easiest/cheapest to harder)
 
My understanding is that the socket gets its ground from the attachment of the socket to the body. Have never had a problem with them and the sockets seem very secure. If there was a bad connection with the ground from the socket, would that keep both lights from working? I doubt both would have a ground problem at the exact time.
 
You will need a WIRING DIAGRAM for that one.

It should be a DUAL FILAMENT BULB (1157 - 12V - two pin) (1956 BIRD?).

Take a test light and try for parking and turn. The test light will provide a separate ground.

How many pins are coming out of the socket/lamp body?
 
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Number one - the horn relay does not affect the lights. . Completely different system. No relay on the lights. Do you mean the connectors on the inner fender panels?


Like others have said - check the grounds at both lights. Make up a wire with two clips on the ends and ground the light bodies to a good surface. Make up two, one for each light. See if that makes them work correctly.


Other thing to check is the connector on the left inner fender to make sure all the wires are connected securely. The check to make sure they are in the proper spots.


Then check the connector coming from the steering column. Same deal as the connector noted above.
 
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Are the two parking/turn lights connected in any way such if one goes out the other won’t work either? Would a bad ground on one make both not work? I ask because I have never had any trouble with these lights and all of a sudden they both go out at the same time.
 
Both sides are not connected and usually a problem with one will not affect the other. The only "connection" would be the power source and if that was interrupted all the signal lights would not work.


zuburg said:
Are the two parking/turn lights connected in any way such if one goes out the other won’t work either? Would a bad ground on one make both not work? I ask because I have never had any trouble with these lights and all of a sudden they both go out at the same time.
Click to expand...
 
Thanks, that’s what I would have guessed. The rear turn signals work fine as do the dash lights (although they both flash any time you turn it left or right). This is why I’m so confused. I don’t believe the grounds on both sides could have gone bad at the same time. I will try to test for power as soon as I can. Do you know if each light has a separate power wire from the wiring harness or does the power go to one light and then continue over to the other? That could explain both going out at the same time.
 
zuburg said:
Symptoms:
When you turn on either turn signal, both turn-signal indicators on the dashboard flash.
* Neither front turn-signal light works.
* Both rear turn signals work.

Both relays on the front inner fenders were replaced recently to solve a horn problem. I understand those relays control both the horn and headlights. Do they have anything to do with front turn signals?

What things should I do to correct (of course, sorted by easiest/cheapest to harder)
Click to expand...

zuburg said:
Are the two parking/turn lights connected in any way such if one goes out the other won’t work either? Would a bad ground on one make both not work? I ask because I have never had any trouble with these lights and all of a sudden they both go out at the same time.
Click to expand...
The only "relay" on the left front fender of an original '56 Bird is the horn relay. As Paul pointed out it has nothing to do w/ headlights, turn signals or parking lights.

You're probably thinking of the two black junction blocks, one behind each headlight. They connect wiring from the dash to the: hi & lo headlights and turn signals & parking lights. If you didn't have a problem before replacing them, they likely aren't connected correctly.

You'll likely need a 12v test light and a jumper wire from a 12v source to check the function of individual wires.

Photos 1 and 2. Rear view
Look closely, the junction block on the left front inner fender features side-by-side shared connectors and two independent connectors. The electrical connections inside are just small metal tubes that pass straight thru the block from rear to front.
If dash power wires on the rear side of the block and the wires on the front side to the lighting fixtures aren't connected correctly strange things will indeed happen with the lights up front.

Photo 3. the parking light (and tail light) bulbs are similar to headlights in having two filaments inside each bulb. Each filament works independently of the other unless the external Ground connection fails.

Photo 4. Electrical paths of connections in the upper half of the left front junction block.
Solid yellow arrows are power coming from dash area. Yellow line arrows are for power out to each bulb filament.
Also notice three Ground lug connections on the left mounting screw. One in the wiring harness from the dash area and one for each headlight. These should be connected to the body.

Photo 5. electrical paths of connections in the lower half of the left front junction block.


Photo 6. The right front junction block has four independent connections. Lighting power connections passing over the radiator from the left front junction block connect straight thru to the wires for each filament.
.
 

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I have to confess about my stupidity. When I first asked about my front turn signal lights not working I wasn’t aware they were also parking lights. So this morning I checked and of course they worked fine, so that solves whether they have a good ground. I have been researching and plan to test the 6 wires coming out of the turn indicator in the steering column (that are exposed under the dash) to see if they all are working as they are supposed to. Those results should point us in the right direction. I hope it doesn’t turn out to be the switch in the column as that doesn’t sound like a lot of fun.

I’ll be back, either with good results or more questions.
 
Per the Ford schematic of the signal lights, power comes from the ignition switch, to the flasher, through the junction block and then to the steering column turn signal switch. From there the power goes out through the same junction block when the lever is actuated , to the junction block on the inner fender panel and then to the front signal lights ( the rears go back after the first junction block).


If you have power to the junction block on the inner fender, then that would indicate the the wires coming out of the other side are wrong.


Since the rear signal lights are working ok, the switch seems to be getting power. Not to say that the switch may be 100 %


With a test light, check all the wires for power to see if there is a disconnect somewhere. Remember, that the test light will flash just like the signal lights. Start with the junction block on the inner fender and work your way back to the switch. The wires to the inner fender block are white with a blue band (right) and green with a white band (left) before the junction block. After the junction block, both are white/blue. Word of caution - the second color may not be a band but the color of the wire connector


Bad grounds can cause all sorts of screwy things to happen so I do not rule out a bad ground somewhere
 
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zuburg said:
. . . I have been researching and plan to test the 6 wires coming out of the turn indicator in the steering column (that are exposed under the dash) to see if they all are working as they are supposed to. Those results should point us in the right direction. I hope it doesn’t turn out to be the switch in the column as that doesn’t sound like a lot of fun.

I’ll be back, either with good results or more questions.
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Concentrate on the two front junction blocks first. Since you replaced them and apparently didn't have this problem before... those parts 'should' be where the problem is.

If you didn't previously change the turn signal wiring block next to the steering column and didn't have this problem before, leave it alone. It's way more of a headache to think about than the two junction blocks up front.

I'll just leave this diagram here,
you are allowed to run from the room in fright. 'No no not that!'. :eek:
.
 

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Thanks to all for the great detail. I found most of this from ChatGPT. I plan to test the front junction boxes first. Some work done by the mechanic included replacing the horn relay and some front wiring harness (at their suggestion as some of the wiring was worn and sketchy) so I’m guessing that may included the junction boxes and got something wrong. I feel I should be able to test all the connections and confirm the problem.
 
I think I misspoke. The work my mechanic did was replace the horn relay and some front wiring harness, not the junction boxes. So it looks like new wires are coming out of the junction boxes so I will try to confirm those are plugged into the right place as well as confirm power is coming in for the signal lights.
 
To do all you want to do, you will need a WIRING SCHEMATIC.

Do you have the 1956 WORKSHOP MANUAL or a separate schematic?

Hopefully the mechanic had a diagram.
 
To do all you want to do, you will need a WIRING SCHEMATIC.

Do you have the 1956 WORKSHOP MANUAL or a separate schematic?

Hopefully the mechanic had a diagram.
 
I do have a shop manual as well as a printout of the wiring schematic. My trouble is actually finding any wire in question on the car and colors seem to never match the schematic.
 
Regarding colors, I have found them to be pretty good according to the electrical installation manual. As I mentioned before, and I don't know if this was how ford did it, but the secondary color was not on the wire itself but on the end of the wire on the replacement harnesses.




zuburg said:
I do have a shop manual as well as a printout of the wiring schematic. My trouble is actually finding any wire in question on the car and colors seem to never match the schematic.
Click to expand...
 
You must be talking about what I have been calling a boot. A soft rubber thing on the barrel connector. I have noticed those. Does each specific wire need to be in a particular position on the junction block or just as long as the input and output wires are lined up in the same position, it works. I’m trying to figure which wire is what. It was no problem when I could see one end of the wire and trace it to the other end like the wires from the horn relay to the horns. It’s the random wires coming out of the old harness and colors are hard to discern.
 
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