I am not a voltage person or into wiring to understand every car and its functions and dynamics of all of it. I can only say that each car has its own issues that has to be trial and error to be remedied. Dont put off some of the simple things unless you have tried it...as in just turning 180 for polarity or cleaning a contact or bending a wire for contact.
disclaimer, my story, dont have to read:
I bought LEDs for my 84 Regal and I was running into issues with them operating properly as well. With the lights off, all the lights worked fine. It wasn't until I drove at nighttime and tried to use my turn signal and it just stayed lit....but it was ONLY the drivers side. I installed the resistors thinking that would help, even though I didn't get any hyperflash. They made no difference whatsoever. I got kind of pissed knowing the website said I needed them but I dont. What a waste of money. Anyhow, I read a bunch online trying to find a solution, which in an "old" car wasn't easy to find due to the lack of people doing it. I ended up buying an electronic flasher at the local auto parts and it helped a little but didnt fix my problem. I was kind of stumped and was about to give up. I hit the internet again and kept looking for other solutions. I even went as far as turning the bulbs 180 just in case the polarity made a difference. NOPE. I ended up buying a different flasher with a ground and low and behold all my signals and lights work. Granted, drivers side is still a little slower than it should but I'll take it.
My understanding is that no single older car, G Body is in that category too, has a single remedy when it comes to the newer LED lighting in the vehicles. So, DON'T give up if its what you really want to have in your vehicle. It might be frustrating but, troubleshoot everything one by one with the cheapest thing first (FREE) to replacing, or adding things (flashers, resistors, new wiring) until you find a solution and then share with others.
Not saying this is or will help but, this is what I used for mine.:
http://rover.ebay.com/rover/1/711-5...0001&campid=5335822911&icep_item=401773311870