Resolved Ignition switch questionable

Dontknowchit · Mar 14, 2025

I had intermittent turn signals so figured it was time to replace the ignition switch. Sure enough, it was coming apart. I replaced it and now I have no headlights. Figured it was a bad pigtail block so painstakingly documented wire position in place and then depinned the harness.

There was no change

So I tracked down the diagram and ran into a mostly correct harness except for 2 wires not accounted for.

I have an extra pinkish-purple wire connected to the pink/white at the base of the harness and the one port that is typically open, is filled with a thick red and yellow.

Now all these wires look very factory, but no idea what they are.

Before I cut the loom and start tracing these all the way back, any ideas?

I rewired my headlight switch with a new pigtail from LMR last year and that is all tidy. I suppose I could have fried the switch but when I pull back on the flash to pass, the headlights light up just fine and all was working before I swapped out the switch. These really look like factory spade connectors and crimps, I'm just guessing they were meant for somewhere else? Or possibly the bad switch was making contact with something that made it all look correct but it wasn't? The only noticable issue is the headlights.

Noobz347 · Mar 14, 2025

When we start getting into conversations about trying to find the exact spot that our 30 year old wiring harnesses have issues:

Run yourself a new wire from your known good test points.
You can even buy wire that duplicates the OEM colors if you like.
Once you get it run where you want it, have tested it, and are satisfied with it, you can clip the old one out and terminate any ends you don't wish to dig out. I have a day-glow, yellow shrink tube that I like to use. It lets me know WTF I did when I see it again.

So far, I have maybe 3 such wires. The bonus to this plan is that the wiring diagram is still correct, even if the routing isn't.

Dontknowchit · Mar 14, 2025

"It lets me know WTF I did when I see it again."
Hilarious

at this point im just searching all the "veryhelpful" diagrams to see if I can figure out where this wire should live, that port on the iginition is supposed to be empty. It must have something to do with the headlights either power or feed to the fuse.

AeroCoupe · Mar 14, 2025

So what year car, motor, and trim level? Not saying I can help here just saying it’s good info to help troubleshoot.

General karthief · Mar 15, 2025

I believe the head light wiring does not pass through the ignition switch.
Check the diagram again.
It is routed through the multifunction to though.

http://www.veryuseful.com/mustang/tech/engine/images/MustangLights-Horn.gif

AeroCoupe · Mar 15, 2025

That would make sense as you can turn the headlights on without having a key in the car.

General karthief · Mar 16, 2025

AeroCoupe said:
That would make sense as you can turn the headlights on without having a key in the car.

The world is in trouble if I make sense........

AeroCoupe · Mar 16, 2025

I hid under my office desk for a little bit after I hit post reply.

Mustang5L5 · Mar 18, 2025

No year given, but here's 1992

Mustang5L5 · Mar 18, 2025

Wire 977 (purple/white) appears to be a ground. If you test continuity of these wires to ground, i imagine it should ring out. BTW, it's entirely possible that the pink wire is really a faded purple wire, but i can't see if it's solid or also has a white stripe.

Mustang5L5 · Mar 18, 2025

Here's 1988. I checked all 87-93 and it's the same.

This one specifically mentions no connection to pin A1

Dontknowchit · Mar 18, 2025

Thanks to everyone's help I found and fixed the issue!

I have no earthly idea how it got to this state but likley has something to do with the work on the stearing column that was peviously done on this car. The wire at A1 (as seen above) is open, and the wire I had there was the power feed from the multifunction switch. At some point someone thought it went there and actually taped it all up with the other ignition wires........

So all I can surmise (because at this point I cannot recreate) is that the ignition switich was coming apart so badly that power was somehow backfed to the dash switch, causing the headlights to appear to work normally. When I installed the new ignition switch, this accidental success was cut off and the lights no longer worked and once I plugged it back into the right port on the multi-function switch, everything was back to 100%.

No clue how long this has been this way, I've owned and have been working on the car for about a year and a half and the dash headlight switch was rewired by me as it had been previously fried. I've had it in running shape for about 9 months but it was running really badly and only occasionally starting when I got it. Who knows, may have been a project that never "ran right" and it was not like this for too long.

Amazed it did not burn to the ground with all the scooting around town I've done with it in the last 9 months. Good thing I did not drive it to Foxtoberfest like that as planned last fall!

Robman8028 · Jun 18, 2025

General karthief said:
I believe the head light wiring does not pass through the ignition switch.
Check the diagram again.
It is routed through the multifunction to though.

http://www.veryuseful.com/mustang/tech/engine/images/MustangLights-Horn.gif

You are correct!

General karthief · Jun 18, 2025

Robman8028 said:
You are correct!

Resolved Ignition switch questionable

Dontknowchit

Active Member

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Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Dontknowchit

Active Member

AeroCoupe

lube between the nut and the face. I know my lubes

General karthief

wonder how much it would cost to ship you a pair

AeroCoupe

lube between the nut and the face. I know my lubes

General karthief

wonder how much it would cost to ship you a pair

AeroCoupe

lube between the nut and the face. I know my lubes

Mustang5L5

That is…until I whipped out my Bissell

Mustang5L5

That is…until I whipped out my Bissell

Mustang5L5

That is…until I whipped out my Bissell

Dontknowchit

Active Member

Robman8028

Member

General karthief

wonder how much it would cost to ship you a pair

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Resolved Ignition switch questionable

Active Member

Attachments

Stangnet Facilities Maint Tech... Er... Janitor

Active Member

lube between the nut and the face. I know my lubes

wonder how much it would cost to ship you a pair

lube between the nut and the face. I know my lubes

wonder how much it would cost to ship you a pair

lube between the nut and the face. I know my lubes

That is…until I whipped out my Bissell

That is…until I whipped out my Bissell

That is…until I whipped out my Bissell

Active Member

Member

wonder how much it would cost to ship you a pair

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