Author Topic: 67 original GT fog light wiring  (Read 2896 times)

Offline socalgt

  • Hero Member
  • *****
  • Posts: 548
67 original GT fog light wiring
« on: February 14, 2016, 09:24:47 PM »
My fog lights stopped working.  I see a black wire near the switch that is not connected to the switch.  It appears to be one of the three wires from the harness plug, so I assume it is supposed to be attached to the switch, but broke off.  Am I correct?  I've looked at original switches(on Ebay) and they do appear to have the black wire connected to one of the terminals on the switch.

Offline midlife

  • Wiring Guru---let me check your shorts!
  • Global Moderator
  • Hero Member
  • ****
  • Posts: 2164
    • Midlife Harness Restorations
Re: 67 original GT fog light wiring
« Reply #1 on: February 14, 2016, 11:14:37 PM »
IIRC, there are three wires at the switch: blue/black (fog lamp power from the circuit breaker), gray (fog lamp output to the engine compartment) and black or brown (rear running lights).  If the brown or black wire is broken, that should not affect the front fog lamps.
Midlife Harness Restorations - http://midlifeharness.com

Offline socalgt

  • Hero Member
  • *****
  • Posts: 548
Re: 67 original GT fog light wiring
« Reply #2 on: February 15, 2016, 12:40:14 AM »
Interesting....I'll look for another cause for the fog lamps to have just stopped working for no apparent reason.  I haven't done any work, electrical or otherwise, that could have caused them to stop working.

Offline midlife

  • Wiring Guru---let me check your shorts!
  • Global Moderator
  • Hero Member
  • ****
  • Posts: 2164
    • Midlife Harness Restorations
Re: 67 original GT fog light wiring
« Reply #3 on: February 15, 2016, 08:15:24 AM »
The circuit breaker would be my first place to look at.  Apply 12V to one side and see if you have voltage on the other side.  The direction doesn't matter.
Midlife Harness Restorations - http://midlifeharness.com

Offline 67gtasanjose

  • Hero Member
  • *****
  • Posts: 5089
  • "Take the MUSTANG PLEDGE"
Re: 67 original GT fog light wiring
« Reply #4 on: February 15, 2016, 09:40:08 AM »
There are wiring diagrams in the assembly manual that demonstrate where the wires on the back of the switch should be soldered on.
Yes. I would make sure you have power through the circuit breaker first but I would also search where this "mystery wire" goes.
Richard Urch

1967 (11/2/66, S.J.) GTA Luxury Coupe, 289-4V w/Thermactor Emissions, C-4, Int./Ext. Decor +many options

2005 (04/05) GT Premium Convertible, Windveil Blue, Parchment Top w/Med. Parchment interior,  Roush Body Appointments

Offline socalgt

  • Hero Member
  • *****
  • Posts: 548
Re: 67 original GT fog light wiring
« Reply #5 on: February 20, 2016, 03:31:36 PM »
I'm having a hard time finding the circuit breaker.....lot of things in the way...center floor console, a/c, etc.,...could someone be as specific as possible where it would be located on  a car that came from the factory with the fog lights(GT). ( I checked the lights and they work connected directly to the fuse box or battery)  I've been upside down on my back trying to find the breaker, but knowing exactly where to look would  really help.  Attached is a photo of the breaker on a '66....I'm not sure what the orientation of the picture is, or if the '67 breaker would be in the same place.  I bypassed the circuit breaker(wherever it is....) and applied power directly to the switch and the fog lights worked...so...if I could find the circuit breaker I would test it...I removed the ashtray for a better view.  I can see the wires from the switch harness but can't trace them to the breaker...assuming there is one...(you never know with previous owners)

                                                                                                  Thanks in advance for any suggestions
« Last Edit: February 20, 2016, 05:15:30 PM by socalgt »

Offline 67gtasanjose

  • Hero Member
  • *****
  • Posts: 5089
  • "Take the MUSTANG PLEDGE"
Re: 67 original GT fog light wiring
« Reply #6 on: February 20, 2016, 05:56:35 PM »
Page 53 of the Electrical assembly manual has the circuit breaker mounted onto the wiper motor mounting bracket. If you have the convenience group and/or tilt wheel, you may find it on the "L" bracket for the relay center. The 12V power source is spliced into another 12V circuit that feeds through the underdash harness back through the headlamp/underhood harness, connected through the fusible link at the starter solenoid. This under dash 12V source connector is a bullet connector, taped down to the wire harness of ALL 67 Mustangs (with or without factory equipped fog lights), it is located about a foot away from the fuse block if you follow the main harness back towards the wiper motor and instuments from the fuse panel.
Richard Urch

1967 (11/2/66, S.J.) GTA Luxury Coupe, 289-4V w/Thermactor Emissions, C-4, Int./Ext. Decor +many options

2005 (04/05) GT Premium Convertible, Windveil Blue, Parchment Top w/Med. Parchment interior,  Roush Body Appointments

Offline socalgt

  • Hero Member
  • *****
  • Posts: 548
Re: 67 original GT fog light wiring
« Reply #7 on: February 20, 2016, 06:55:53 PM »
What do you mean by the "relay center?"   

Offline socalgt

  • Hero Member
  • *****
  • Posts: 548
Re: 67 original GT fog light wiring
« Reply #8 on: February 20, 2016, 07:00:47 PM »
I have traced the wires from the engine side of the switch harness...they appear to go behind the headlight switch, but I can't see where they go from there....but I understand one should  lead to the circuit breaker?

Offline 67gtasanjose

  • Hero Member
  • *****
  • Posts: 5089
  • "Take the MUSTANG PLEDGE"
Re: 67 original GT fog light wiring
« Reply #9 on: February 20, 2016, 07:38:11 PM »
What do you mean by the "relay center?"

"Relay Center" is a term I gave to the OPTIONAL "L" plate ("bracket" per the manual) used to mount certain relays on options your car MAY NOT have such as Convenience Control or Tilt-Away Steering column. If you do not have either of these options, the "relay center" will not exist and your circuit breaker should be found screwed down to the wiper motor mounting bracket.

Do you have an electrical assembly manual?

I uploaded a couple of shots from the manual, the first one shows the "relay center" (bracket per the assembly manual) as part of the tilt column on page 31. The same bracket also mounts the seat belt light timer for optional deluxe seat belts or optional low fuel relay.
The second image is showing JUST the fog light circuit breaker.
Any or all of these MIGHT mount on this bracket or "relay center" but only if you have the other optonal equipment.
« Last Edit: February 20, 2016, 07:54:41 PM by 67gtasanjose »
Richard Urch

1967 (11/2/66, S.J.) GTA Luxury Coupe, 289-4V w/Thermactor Emissions, C-4, Int./Ext. Decor +many options

2005 (04/05) GT Premium Convertible, Windveil Blue, Parchment Top w/Med. Parchment interior,  Roush Body Appointments

Offline socalgt

  • Hero Member
  • *****
  • Posts: 548
Re: 67 original GT fog light wiring
« Reply #10 on: February 20, 2016, 08:52:59 PM »
I really appreciate your help....finally found it...pretty well hidden...screwed onto a separate bracket which is attached to the wiper motor bracket...I'll attach a picture.  The terminal nuts were loose, so I'll clean them up and test it before I put  it back on.  I'll attach a picture of the bracket in case it helps someone else down the road.  As usual, I had to get" twisted up like  a pretzel" to get it out....Thanks again.  If any one needs it...I'll post a picture of it after putting it back on to see exactly where it attaches.  By the way, does the plastic insulator go under the connections or over them?

Offline socalgt

  • Hero Member
  • *****
  • Posts: 548
Re: 67 original GT fog light wiring
« Reply #11 on: February 21, 2016, 03:32:06 PM »
All is well and the breaker was cleaned and reattached to the bracket.....thanks for the help.

Offline 67gtasanjose

  • Hero Member
  • *****
  • Posts: 5089
  • "Take the MUSTANG PLEDGE"
Re: 67 original GT fog light wiring
« Reply #12 on: March 31, 2016, 10:03:00 AM »
By the way, does the plastic insulator go under the connections or over them?

I didn't see this till now. I'm going over my example today. On mine, the plastic separator went onto the circuit breaker first, followed by the wiring eye connectors, internal toothed wash and last, the nuts.

I suspect mine has been worked on at one point in time. My circuit breaker for one, is different than what socalgt posted an image of. (see 1st image below)
My breaker is turned, mounted inline to the bracket spot welded on the back. I was also missing a toothed washer, so I am suspect of it being a replacement.

Does anyone else with a October, November, December San Jose GT have any pictures of this circuit breaker? (aftermarket looks like socalgt's example too)

Another detail the assembly manual does not show a plastic divider used.

I have a picture(2nd image below) of another Dearborn example without a plastic divider, it also looks like socalgt's example
« Last Edit: March 31, 2016, 10:18:37 AM by 67gtasanjose »
Richard Urch

1967 (11/2/66, S.J.) GTA Luxury Coupe, 289-4V w/Thermactor Emissions, C-4, Int./Ext. Decor +many options

2005 (04/05) GT Premium Convertible, Windveil Blue, Parchment Top w/Med. Parchment interior,  Roush Body Appointments

Offline WT8095

  • Hero Member
  • *****
  • Posts: 940
  • Dave Z.
Re: 67 original GT fog light wiring
« Reply #13 on: April 01, 2016, 02:18:40 PM »
I didn't see this till now. I'm going over my example today. On mine, the plastic separator went onto the circuit breaker first, followed by the wiring eye connectors, internal toothed wash and last, the nuts.

That's the correct sequence. The divider prevents the connectors from touching each other. If they make contact, the circuit breaker is bypassed and you no longer have protection. Everything will seem to be working fine until an overload occurs and the circuit breaker doesn't trip...

You should add a separator to the breaker that doesn't have one. It should have come that way from the factory, but even if it didn't it's an important safety feature. And a lot cheaper than a fire extinguisher.  ;)
Dave Z.

'68 fastback, S-code + C6. Special Paint (Rainbow promotion), DSO 710784. Actual build date 2/7/1968, San Jose.
'69 Cougar convertible, 351W-2V + FMX, Meadowlark Yellow.

Offline 67gtasanjose

  • Hero Member
  • *****
  • Posts: 5089
  • "Take the MUSTANG PLEDGE"
Re: 67 original GT fog light wiring
« Reply #14 on: April 01, 2016, 03:27:21 PM »

You should add a separator to the breaker that doesn't have one. It should have come that way from the factory, but even if it didn't it's an important safety feature. And a lot cheaper than a fire extinguisher.  ;)

Agree, and I have the separator but the assembly manual pictured in another comment shows NO SEPARATOR in the drawing, why I asked. Another note, by adding the separator, it lifts or insulates the contact point of the wiring loop from off the brass (or copper) face of the breaker, leaving only the friction of the tightened threads, pulling against the nut & internal toothed washer (as pictured in assembly manual again).

I would think the added resistance could be a bigger issue. (maybe a possible cause to the O.P.'s problem in the first place ???

Maybe a better idea while still using the separator for safety, bolt the separator down with a 2nd pair of nuts so the contact area of the threads will at least be doubled. This also thinking on the side of "safety verses concours".
« Last Edit: April 01, 2016, 03:33:48 PM by 67gtasanjose »
Richard Urch

1967 (11/2/66, S.J.) GTA Luxury Coupe, 289-4V w/Thermactor Emissions, C-4, Int./Ext. Decor +many options

2005 (04/05) GT Premium Convertible, Windveil Blue, Parchment Top w/Med. Parchment interior,  Roush Body Appointments