1968 Electrical

[whodat]

When the left blinker is on it cancels out the gas gauge and radio. It doesn’t do this for the right blinker. Could this be the Turn Signal switch?


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[speedy02]

Do you have the original style wiring harness or did you upgrade to an aftermarket harness?

 

[speedy02]

If it has the original style wiring I found this diagram on how the radio connects to the cluster.

 

[speedy02]

Wiring diagram for back of cluster.

 

[Ricky Knapik]

The turn signal switch is the root of all eval on our cars! Too much draw for 6 1157 bulbs. If you haven't changed to LED's yet, do it. After you track down your current problem of course.

 

[cmacias24]

I agree with Ricky. Change out the taillight light bulbs with LED before you do anything else and ensure you have proper grounds. The factory bulbs draw too much power, cause the light switch to overheat and you’ll experience dimming instrument panel lights when you apply the brakes, turn on the turn signal and when you drive long enough with the lights on, the lights will cut off for seconds at a time.
Once you do that, stat tracking down the grounds under your dash and ensure they’re tight and that every connector is tight as well.
From my experience, a bad turn signal switch symptom is one side of your lights not working. E.g. the right brake light or right signal.

Hope that helps!
-Cesar


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[Mosesatm]

Check the bulbs and sockets associated with the left turn signal: front bulb, hood bulb, dash bulb, rear bulbs. You may have a corroded bulb/socket shorting out to the body.

 

[Ruppstang]

I have a different column that has a working turn switch that I use to test with. It is a lot of work to change the switch to only find it was a different issue. I suspect it is a ground issue as the turn circuit has nothing to do with the radio.

 

[whodat]

Thanks for the information.
Tonight 2/7/2026 it didn’t do it. I thought that was weird

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[Nazstang]

Noticed you are talking about switching to LEDs. I don't have any issues with lighting at this time but have thought about changing over. Besides changing the bulbs, is there anything else electrical that needs to be addressed before swapping the bulbs?

I see them advertised on CJ and NPD, is one brand better than another? Thanks guys...

 

[Mosesatm]

"Besides changing the bulbs, is there anything else electrical that needs to be addressed before swapping the bulbs?"

You may need to change out your flashers.

 

[Nazstang]

"Besides changing the bulbs, is there anything else electrical that needs to be addressed before swapping the bulbs?"

You may need to change out your flashers.

Got it, thanks for the tip!

 

[cmacias24]

I didn’t have to change the flashers when I swapped out the taillight light bulbs. I read somewhere that you have to change the flasher when you swap all the bulbs in the circuit, but not when they’re mixed.
I purchased the following part number from Super Bright LEDs

1157 LED Bulb - Dual Function 27 SMD LED Tower - BAY15D Bulb

LED replacement bulbs can fit vehicle tail lights, brake lights, reverse lights, turn signals or side marker lights. This 1157 dual-contact, dual-function bulb emits a 360° viewing angle for better, allover light emission with reduced hot spots. The bulb features a tower-style design with a...

www.superbrightleds.com

1157-R27-T-2PK

I hope this is helpful.


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[admin]

What color did you order? The link provided automatically selects the "amber" color, but I'm guessing you went with one of the whites, either "cool" or "natural"?

 

[Mosesatm]

These are the ones I used. https://secure.cougarpartscatalog.c...73-mercury-cougar-1967-1973-ford-mustang.html

Does Scott still poste here?

 

[rvrtrash]

"Does Scott still post here?"
I talked to him about a year ago, but haven't seen him on here in quite a while.

 

[speedy02]

These are the ones I used. https://secure.cougarpartscatalog.c...73-mercury-cougar-1967-1973-ford-mustang.html

Does Scott still poste here?

I plan on upgrading the tail lights to these.


If your looking at interior or gauge lights use the link below. The times I order the 1157 LED from West Coast Cougar it came in a package from HiPo.

HiPo Parts Garage

hipoparts.com

 

[Ricky Knapik]

I plan on upgrading the tail lights to these.


If your looking at interior or gauge lights use the link below. The times I order the 1157 LED from West Coast Cougar it came in a package from HiPo.

HiPo Parts Garage

hipoparts.com

These are what I have. And they're bright! The factories are so dim I always worried about someone rearending me. Not any more!

 

[Nazstang]

Thank you EVERYONE for the response and advice, I definitely have a good starting point now. I'm for sure changing out the tail lights, if I decide to change out front turn signals I'll order the flasher relay. Traffic sucks anymore and I'm also afraid of getting rear ended!

Again, thank you, it's much appreciated!

 

[speedy02]

Thank you EVERYONE for the response and advice, I definitely have a good starting point now. I'm for sure changing out the tail lights, if I decide to change out front turn signals I'll order the flasher relay. Traffic sucks anymore and I'm also afraid of getting rear ended!

Again, thank you, it's much appreciated!

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