Turn signals work only with ignition on & Engine off.

DienstXIV · Jul 2, 2025

Hey everyone, I have a 1985 Mustang GT that is currently my daily driver. Driving to work this morning, my turn signals quit working, no lights on dash, no lights on exterior, no ticking. I changed out the flasher and noticed that when the ignition is on but the engine is off, the turn signals work but when I turn the engine on, they stop working. Hazards work fine either way.

Anyone have this issue and known where I should look to fix it?

Any advice is much appreciated
Cheers,
Alex

AeroCoupe · Jul 3, 2025

I would start with the ignition switch (not the lock cylinder) as they have a tendency to have issues.

85GTStangGuy · Jul 3, 2025

I second what @AeroCoupe said.

More Information for MOTORCRAFT SW2474

DienstXIV · Jul 3, 2025

AeroCoupe said:
I would start with the ignition switch (not the lock cylinder) as they have a tendency to have issues.

Thanks for the advice, I changed my ignition switch about 5 years ago I am surprised it would be that but it wasn't hard to install and O'Reilly's has one in stock so I'll get one today and put it in tomorrow and let you guys know how it works out.

AeroCoupe · Jul 3, 2025

Some simple probing with a test light will tell you if the current one is okay with it being g replaced in the last 5 years I’d assume it’s good.

My next guess would be the multifunction switch a.k.a. The turn signal switch.

DienstXIV · Jul 3, 2025

AeroCoupe said:
Some simple probing with a test light will tell you if the current one is okay with it being g replaced in the last 5 years I’d assume it’s good.

My next guess would be the multifunction switch a.k.a. The turn signal switch.

You wouldn't happen to have a wiring diagram of this area for a 1985 you can post would you?

Where is the multifunction switch located?

AeroCoupe · Jul 3, 2025

It’s the turn signal switch which is in the steering column. It’s called a multifunction switch as it does turn signals, hi/lo beam, and the hazards.

https://lmr.com/item/LRS-13359J/mustang-turn-signal-switch-w-flash-to-pass-84-86

This is for an 86 so similar:

https://www.veryuseful.com/mustang/tech/engine/images/Mustang-86-Lighting-Diagram.gif

You should invest into one of these:

1985 Mustang Capri Electrical & Vacuum Trouble-Shooting Manual (EVTM)

fordmanuals.com

I have this type of wiring diagrams for both of my cars and they have saved my butt several times:

Ford Mustang, Capri 1985 Wiring Diagrams Book | eBay

Vehicle ModelMustang, Capri. TypeWiring Diagrams.

ebay.us

DienstXIV · Jul 7, 2025

SOLVED!!!

Hey thanks everyone for the help. It turned out to be my 5 year old ignition switch that I bought at LMR with less than 10,000 miles on it. The body of it started to separated, I attached a video so you know what I mean. This time I went for an ignition switch from O'Reilly's with a lifetime warranty.

Cheers,
Alex

Turn signals work only with ignition on & Engine off.

DienstXIV

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AeroCoupe

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

85GTStangGuy

DienstXIV

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AeroCoupe

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

DienstXIV

Member

AeroCoupe

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

1985 Mustang Capri Electrical & Vacuum Trouble-Shooting Manual (EVTM)

Ford Mustang, Capri 1985 Wiring Diagrams Book | eBay

DienstXIV

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