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1967 GT500
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Discussion Starter · #1 ·
I have a turn signal and emergency flasher problem. I have been reading through my Osborne manuals and the 1967 mustang, cougar and fairlane service manual as well as trying to jumper and continuity the problem. In the diag section of the service manual, I see what appears to be very similar to what I am experiencing in the turn signals and emergency flasher. I have ordered from NPD the only flasher assy listed for 1967. It seems to be a combo flasher for turn signals and emergency. Despite the fact that the electrical diagrams list them separately in the service manuals. Are they one and the same on a 1967? Secondly, the diag section of the service manual says that I may have 2 wires crossed at the 4 wire 'turn signal indicator relay' or may need a new one. This can't be the same part that I ordered from NPD as I believe the NPD is a 2 wire flasher? The NPD pics don't show the back. Is there a " turn signal indicator relay"? EBay shows an NOS C7WB-13A366-A that doesn't look anything like the NPD one. Thanks.
 

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I believe that relay is for Cougar's and Shelby's with sequential turn signals. What are the symptoms you are having?
 

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1967 GT500
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Discussion Starter · #3 ·
When the left turn signals are on, I am good front and back. When the right signals are on, I get weak front and back with faint bleed over to left front and back. When emergency is on, I get strong left, weak right front and back. When running lights or brake lights are on, i get strong left, weak right front and back.
 

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Discussion Starter · #4 ·
I just replaced steering wheel harness. All color coded wires map correctly and have good continuity on dash side of connector. I have concours voltage regulator on order, all new bulbs on order and flasher.
 

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You have a ground issue on the right side either at the front or back. Grab a suitable jumper wire with alligator clips on both ends and attach one to a known good ground and the other to the bulb housing... one at a time. Whichever one solves the problem is the offender. I've seen some reproduction front turn signal housings with poor grounds.
 

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Discussion Starter · #6 ·
I tried doing some of that to no avail. Odd thing is wire in rear goes from left to right so doesn't make sense left good, right bad. I also cleaned contact on trunk lid latch housing by gas filler. I may have to run/splice in a good ground on the right and see what happens. I have a shelby so I have 3 lights each can in back but not sequential.
 

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Discussion Starter · #7 ·
Also bulbs have inner and outer grounds and positive on each socket. They don't ground to the housing. I have to disconnect them to access the + and -.
 

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Also bulbs have inner and outer grounds and positive on each socket. They don't ground to the housing. I have to disconnect them to access the + and -.
What do you mean "inner and outer grounds"? Each bulb should have 2 filaments and 2 pins on the base. One is power for the parking lamps and the other is power for the stop and turn. The bulbs ground through the brass base to the housing of the socket.
 

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Discussion Starter · #9 ·
I described poorly. I mean the bulbs ground to socket, socket grounds to wiring harness, not through housing. The harness has a self contained + and - rubber boot that attaches to each socket. This is original to car and shelbys. The ground in the harness then grounds to the body of the car at the gas filler tube housing.
 

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Rock Auto lists several 2 prong flashers, all with a 552 number.

I just bought a couple of the electronic ones for my 67. $2.83 each

RA lists p/n C5AZ 13350 B for the 67 turn and emer flasher.
 

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Back in 67 (60's) yes Ford used two different p/n flashers. The emergency flasher was a bit more "heavy duty" because it had to run all the lights, not just one side.
Now a days, vendors sell one size does all because I believe it's the heavy duty one for both functions. The 552 sounds right.
My .02, if you have problem with both front & rear RH, I'd be inclined to think problem in column.
Has it always been a problem? What recent work if any have you done?
 

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Are you using LEDs or normal light bulbs? Some LEDs can have problems like that.

Are all of the light bulbs dual filament 1157s? Some others can physically fit in the socket but won't work right.

Maybe try one bulb in one socket at a time and work your way up to all three bulbs and all three sockets just to see if you can isolate it to an individual bulb or socket.
 

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These problems usually end up being ground problems. As I have disassembled my 67 I am finding lots of wiring issues. Bad terminals, broken terminals, corroded terminals, missing grounds, grounds on paint, not bare metal, undersize wires, bad alt harness. These cars are 55+ years old. Check everything.
 

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Simple to confirm you have ground problem at the front and rear. Be two separate issues if so.
Use ohm meter, in trunk one meter lead to a clean bare chassis metal, other lead to base Rh bulb housing. Meter should go to zero or beep, meaning good ground connection. Can also move lead from bulb socket to metal of tail light housing, should also have good ground readings. If good zero reading, move on to front light housing, do the same. If good ground readings up front, start looking elsewhere. What make think problem elsewhere, when you hit brake pedal, you have same light issues
 

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Discussion Starter · #15 ·
I already replaced steering column wiring twice as I thought that was it, but it wasn't. I mapped all color coded wires from steering wheel side connector to dash side connector and all good. All continuity good on dash side of harness from steering column hub. Originally changed it because of a burned horn contact in steering wheel harness. I still have to find that short. Horns work sporadically now with new harness. So is there 2 flasher assys that I have to find and change? I am using normal 1157's being replaced as they are on order. I just bought the car in March with these issues. I have the same issues with brake and running lights as well as turn signals and flashers. Left turn signal strong front and back. Right turn signal weak as hell front and back and bleeds over so left front and back signals also go on weakly. Weak right running and brake lights. Emergency flasher turns on left strong, right barely see it. I started to check grounds in trunk. Waiting for all new bulbs to come in. It's a 1967 Shelby so rear lights ground via wiring harness, not light housing.
 

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Since you have "weak blinking lights" rh on both front and rear, I say problem has to be under dash, somewhere. Perhaps the main harness connection behind driver side kick panel, unplug it and look at pins in the connector Check and see if they are fully pushed into housing. You can also use a volt meter at that same connector. Take a reading of both RH & LH blinking. If you see a weaker reading on the RH side at connector, them problem most definitely under dash. Proper 12v never getting to back, or front lights.
You gotta isolated where you loose strong 12v reading.
 

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Evert 60s car I ever owned the turn and emer flashers were a PITA to get to. Why didnt they mount those near the glove box or somewhere that a normal sized person could get to them? The same with the fuse box.
 
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