LED taillight issues

[TruckIt75]

Hey everyone I have a ‘75 GMC Sierra Grande. I’ve had led lights all around on my truck for the last 4 years. I recently cracked the driver side USA1 led tail light and ordered a new pair. I only changed out the one busted lense but now have no turn signals in the tail lights if the lights are on. Front signals work as well as the dash indicators. With the lights off they function normal. With the lights on if you use a signal it just turns a brighter red. I cleaned up the ground in back, tried turning the bulb inserts around, fuses seem good. Just really drawing a blank here and I’m sure it’s a very simple fix.
Thanks in advance

 

[xm20k]

Did you swap both they may be a different style circuit and using one new assembly with an old assembly may be an issue.

 

[TruckIt75]

I didn’t think of that. I’ll give it a try this afternoon thank you

 

[TotalyHucked]

It won't explain why the old ones didn't need it and the new ones do, but you might try splicing in a 50ohm resister in each corner. I had to do that when I put LED tails/front parking lights in my truck.

 

[TruckIt75]

I guess I’ll give that a shot too.
I tried putting 2 new lights and it didn’t work. The socket works with a regular LED bulb in it.
Even the hazzards function properly it’s only lights on turn signals

 

[xm20k]

Turn signals are you running an electronic flasher? On mine everything worked 4 ways would even flash because 6 bulbs had enough load, but the turn signals would not. I put one of the electronic flashers in and the turn signals worked.

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[TruckIt75]

So I have the 2 hooked up on the fuse block. One for the hazzards and one for the brake lights or however it goes. I did that when I first upgraded the lights.

 

[NLD79K10]

Have you tried changing the dip switch settings on the circuit boards inside of the tail light units? Sometimes LED taillights like this can be finicky about input signals and unwilling to work in some modes.

 

[xm20k]

Have you tried changing the dip switch settings on the circuit boards inside of the tail light units? Sometimes LED taillights like this can be finicky about input signals and unwilling to work in some modes.

Good shout if they are like mine they have a setting for a sweeping mode vs solid on off