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Discussion Starter #1
Any ideas are greatly appreciated.
I have a set of GT500 sequential taillights in my 68. I don't know the brand name but I purchased them from themustangshop in WA.

The sequential circuit board plugs into the flasher plug and is also grounded to the metal dash.

Since I purchased them, they have never worked right. Everything works great when the key is off, accessory and even in run (turn signal only with acc and on position). But, once the car is running, the taillights won't work, brake lights or turn signals. Sometimes there will be a little blip of light but that's it.

The kit's led panels was a plug and play with my factory 1157 receptical. That is grounded twice, once through the wire loom and one externally to the tail panel.

I have traced down and tested the turn signal and brake wiring from the dash all the way back with a test light and volt meter. I have 11.3 v when the car is not running and 14.30 v when it is running all the way to the plug at the taillights.

I disconnected the alt thinking 14+ is too much for the LED's. No luck.

Here's one thing that is strange. I unplugged the LED panels at the factory plug and popped a 1157 in and the damn thing works perfect with the car running. I can't understand why the LEDs won't work with the engine running. Is it possible I need a condensor? Could it be electronic noise that's killing them?
 

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Discussion Starter #2
One other thing I forgot to mention. The first thing I did when trying to fix this is I replaced the ignition switch.
 

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it works in run without engine on

but wont'd with engine running??

you sure?
 

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Discussion Starter #4
Yes Sir, they work with the key "on" but once the engine is running they won't work. Whats ever stranger, the 1157 bulb will work with the engine running. That is why I replaced the ignition switch with a new unit. I figured it was in the switch.
 

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little confusing

RUN, CRANK

are these LED or 1157 incad???
 

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give me a bit on this
 

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you have a link to install manual and site you bought it from?
 

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Discussion Starter #12
I purchased them 8+ years ago from TMS in WA state. If you go to their web site they don't list any parts for sale. I don't know a brand name. I emailed them last week and they said this was the first time they've ever heard of such a problem. I did a google search and I can't even find pictures of the LEDs like mine.
 

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post some close ups of the boards and the plug terminal

without knowing how the controller was programmed or if you need an electronic flasher

you may need to buy a new kit with proper support
 

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Discussion Starter #14
I would like to try a noise suppressor first before I remove the tail panel. Just a last ditch effort on my part. Taking my tail panel off will be a pain in the arse. I will keep you updated. I appreciate your help and have a feeling I'll still be asking for it.
 

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may help

maybe electronic flasher
 

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Discussion Starter #16
Well, today is a great day! I figured it out. It wasn't electrical noise, it was too much voltage. I purchased two load resistors from NAPA today and that fixed my problem. These are Pilot Automotive part # IL-LDRS-A. They are used to slow the high speed LEDs in a vehicle. They reduced the voltage enough to allow my LEDS to function perfect.

Thank you indy2000 for hanging with me.

Hopefully this will help someone sometime.
 

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that is great news!!

have fun with that beast!!
 
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