thats happens because of the current that they use. i have an 86 and it does the same thing.

 

I see. It never did it before just recently. I still have yet to get in there and look. Sorry no update. But now my drivers side door jamb switch makes the horn blare when you open the door. I do not know if it is related to the blinkers or not. Seems like something must have shorted out.

 

just joined today and this is my first post. lucky you :-) have you checked all the bulbs that flash when the signal is turned on? That used to be a dead give away years ago that there was a bulb out somewhere. regarding the new problem - does the interior light come on when you hit the horn? it's an odd question i know, but may give an insight to the cause. see what happens with the fast flashing first - once that is solved go on to the horn issue. does it also happen when the passenger door is opened?

 

I do not know if the interior light works or not. I have not had a bulb in since i first bought the truck. I was having quite a few electrical problems then. I have had the dash rewired and did not bother putting a bulb back in. I can tell you that it was only with the drivers door open. I have checked all the bulbs. One did burn out. I replaced it. It was still rapid but currently is at normal speed. The volts still twitch in sequence with the signal though.