The left turn signal flashes rapidly in my 86 na. The right one works fine. I have checked for a burned light, different bulbs, and the fuses. Everything is fine. Does anyone know what could cause this?

 

smaller bulb, or its burned out and if it looks like its not still replace it.

 

this can happen when the bulb is loose. and just barely touching the contact points in its socket. took me a while to figure it out when it happened to me, but that was my experience. take the bulb out, and clean the socket too. that may help.

 

Bad bulb, too much resistance in a bulb socket, or a bad flasher board in the CPU (in order of most likely).

 

all bulbs work and even tried to swap between left and the right ones and still same problem.

 

HOw to check for too much resistance and how do I fix?

 

you have too much power surging on ur left side, i had the same problem cept i wasn't trying to slow mines down, i was speeding it up to match.

 

Just replace the bulb.

 

Check the grounds on the sockets with a multimeter. I have had that problem with a socket ground and the lamp would feed back through the park lamp circut causing some weard hard to find problems. Also if all else checks ok try checking the cpu flasher section for open solder joints. Most of the time the bad flasher can be fixed with just soldering the connections on the cpu board flasher section. Located drivers side kick pannel near fusebox.

 

Ahh, yeah, okay... please explain how a ground can back feed on a positive trigger circuit that has no relays.

 

What i am saying here is if the socket ground is lifted by bad connections etc.. the same grounds are shared with other lamps on the rear and in most cases it will ground through the filiment of another lamp. This is more common on two filiment lamps. I have seen some weard things from broken or dirty ground connections. We have spent many hours troubleshooting just to find out some ground was not what it should be. I just like to cover all the simple basics and most of the time you will find the problem to be there. Also check all the plugs where the harness plugs into the sockets etc.. they sometimes fail over time.