ConcoursMustang Forums
1st Generation 1964 1/2 - 1973 - Questions & general discussions that apply to a specific year => 1969 - 70 Shelby => Topic started by: mbyers on March 23, 2025, 05:14:41 PM
-
Hello Members
I need some advice on unusual electrical issue w my 69 GT 350 vert. It?s completely restored but still has all original wire harnesses. What?s happening is when I activate fog lights , the brake lights come on continuously. I checked all harnesses under console and in dash and to trunk and are all intact and no obvious wiring damage or exposed wires. My research indicates this was common for this year model but finding info on how to repair problem not easily found. There is a thread on this forum in ?13 by member Stribling who describes exact problem but his explanation on how he fixed issue not easily followed. Some sources point to turn signal cam but before I remove steering wheel I wanted to check with you guys first before tearing into things. Any one experience this problem and/or have some advice on how to troubleshoot issue?
Thx
Matt
-
The turn switch can be the source of many problems. You are correct it is a pain to tear it all apart and find it was something else. To solve this problem, I have another working column that I just plug in to the car and see if anything changes. When you turn on the fog lights the taillights should come on.
Good luck.
-
Are you sure it is brake lights that turn on and not running lights? Most foglamp systems also turn on the running lights.
-
More I think about it, I do believe it?s running lights and not brake lights?.. my bad. What was logic behind Ford wiring it that way? What is strange is my Lucas lights don?t work?.. no power to lights. When I turn on fog lights , ammeter/oil pressure lights and interior lights come on. Is that common as well? Is there an inline fuse for foglight harness?
-
There should be a circuit breaker near the fuse block for the fog light. An electrical assembly manual would be a great help to you in solving some of these problems.
-
What was logic behind Ford wiring it that way?
Fog lights are supposed to be used in the fog, and "running lights" are also required to be on. To wire fog lamps to do that, Ford "tapped" into the regular headlight circuit in the simplest way.
When I turn on fog lights , ammeter/oil pressure lights and interior lights come on. Is that common as well?
Same as above. Both my 65 GT and 66 GT Mustangs are wired similarly.
What is strange is my Lucas lights don?t work?.. no power to lights.
Sorry, what Lucas lights?
An electrical assembly manual would be a great help to you in solving some of these problems.
That's an understatement. Get a full set of Mustang Assembly Manuals.
Jim
-
There is a thin supplement to the 69 "Shop manuals" specifically for the Shelby GT350 500. In it is a Shelby wiring schematic for the Shelby unique wiring added to the base Mustang model during conversion. It is not in any of the regular Mustang manuals.
-
The Shelby fog light breaker for the Lucas lights can be found under the console .