Need help 67 hazard flashers not working

THS70 · Jan 21, 2026

Hi, currently my hazards do not work. Originally it wasn't getting power to the hazards wire ( red/white wire) I ran direct power from the #5 fuse to it and now the hazard lights stay fully green and do not flash when I push the button in. I did install a new Hazard flasher relay and even swap it out with my turn signal flasher relay and it still didn't work. All my other lights, turn signals and horn work.
Any help greatly appreciated. Its the last thing I need so my son can safely drive it. Thanks

THS70 · Jan 21, 2026

Sorry not sure why it wasn't posted correctly

GOvert · Jan 21, 2026

Now I'm not looking at a wiring diagram so don't hold me to this as fact or not. The same summer as my stroke, 6 years ago, I was working on a 1970 Mustang with hazard and signal switch issues. I kind of remembering an aha moment when, with a wiring diagram, discovered that the turn signal circuit, the emergency flashers circuit and the brake lights circuit were all separate and were fed 3 different ways. I know this doesn't really help much. Maybe someone else here on the forum could direct you to a wiring diagram. A "colorized" version would make it a lot easier to read. Something is feeding the circuit without it going through its designated flasher.

THS70 · Jan 21, 2026

GOvert said:
Now I'm not looking at a wiring diagram so don't hold me to this as fact or not. The same summer as my stroke, 6 years ago, I was working on a 1970 Mustang with hazard and signal switch issues. I kind of remembering an aha moment when, with a wiring diagram, discovered that the turn signal circuit, the emergency flashers circuit and the brake lights circuit were all separate and were fed 3 different ways. I know this doesn't really help much. Maybe someone else here on the forum could direct you to a wiring diagram. A "colorized" version would make it a lot easier to read. Something is feeding the circuit without it going through its designated flasher.

Thank you I appreciate the response and input. Hopefully somone has information on it.

Mcmahst · Jan 21, 2026

The likely culprit is the turn signal switch (TSS). I’ve attached my 68 colorized wiring diagram, not exactly a 67, but I believe both years used the same hazard wiring. Fuse 4 is the power to the overall system, but the TSS routes the power. It’s not a usual problem, just an annoying one. Look over the diagram. Good luck

THS70 · Jan 21, 2026

Mcmahst said:
The likely culprit is the turn signal switch (TSS). I’ve attached my 68 colorized wiring diagram, not exactly a 67, but I believe both years used the same hazard wiring. Fuse 4 is the power to the overall system, but the TSS routes the power. It’s not a usual problem, just an annoying one. Look over the diagram. Good luck

Thank you, I forgot to mention that it does have a new turn signal switch as well. I'm really stuck and it sucks lol. Appreciate the response

GOvert · Jan 22, 2026

@THS70 Here are the results from a 1967 Mustang wiring diagram search.
1967 Mustang wiring diagrams

THS70 · Jan 22, 2026

Forgot to mention that I did install all rear new LED light bulbs. Turn signals still work but the hazards do not flash. Stay continuous green

Realmongo · Jan 22, 2026

THS70 said:
Forgot to mention that I did install all rear new LED light bulbs. Turn signals still work but the hazards do not flash. Stay continuous green

I wonder if that would cause you to have to install a heavy duty flasher.

Mcmahst · Jan 22, 2026

Did you install a Flasher design to work with LED bulbs? Some people have reported that they swap out their bulbs for LEDs and their turn signals work, but for some reason, the hazards don’t work any longer. So first, you might try putting the old bulbs back in as a test to ensure the system is working. Then, if that proves true, you can get a flasher specifically designed for LED circuits. They make it because LEDs don’t have enough current draw to enable the by-metal strip in the flashing unit from working.Good luck.

THS70 · Jan 24, 2026

GOvert said:
@THS70 Here are the results from a 1967 Mustang wiring diagram search.
1967 Mustang wiring diagrams

Thank you

GOvert · Jan 24, 2026

@Mcmahst Would that be a solid-state flasher needed for LED lights? If it were me, I would find a kit that makes '67-'68 LED taillamps flash sequential similar to the old Cougars. I've been behind one of these two-year Mustangs and it gets your attention. I finally had time to pick apart the link that I posted. A guy has them for free.
PDF of '67 Mustang wiring colorized tip: put on your readers!

Mcmahst · Jan 24, 2026

Yea, here is a flasher for LED lights, but nothing fancy, just a plug and play replacement:

LED Flasher - 2 Terminal For 1964-73 Mustang | eBay

Get all the advantages of solid-state electronics and LED bulbs in a classic Mustang Tail Light. Mustang Is A Registered Trademark Of The Ford Motor Company

www.ebay.com

It’s an EBay item, but plenty of other folks sell them. Good luck.

Noobz347 · Jan 24, 2026

Realmongo said:
I wonder if that would cause you to have to install a heavy duty flasher.

That actually makes it worse. LEDs don't pull anything for current.

I honestly do not understand this fascination with LEDs in every socket or [any] in older cars. They just don't look right to me and create more issues than they resolve.

Realmongo · Jan 29, 2026

Noobz347 said:
That actually makes it worse. LEDs don't pull anything for current.

I honestly do not understand this fascination with LEDs in every socket or [any] in older cars. They just don't look right to me and create more issues than they resolve.

I figured it needed some form of flasher other than the standard one.

Noobz347 · Jan 29, 2026

I "think" there are flash modules just for LEDs these days.

Something like this should help:

EP27 LED Turn Signal Flasher

Features Compatible with LED bulbs Prevents hyperflash errors Simple swap for original module Direct fitment and proper sizing Flasher Hyperblink Fix. Why do you need this module? When your factory turn signal bulbs go out, your vehicle's flasher senses that less power is being used, and it...

www.diodedynamics.com

But I have never tried one or done an LED conversion. I heard about these from another member.

Need help 67 hazard flashers not working

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