I replaced regular lights with LED's on my 1995 Ford F250 7.3 turbo. The blinkers would take 10 to 15 seconds to start blink and would blink really slow. The other issues include: radio would cut out (intermittently); transmission (automatic) would shift up after getting to desired gear; cruise control stopped working; lost 7MPH (from 72 to 65/64) at 2000RPM's; and my programmer stopped working. I went to the auto parts store and they told me to install a ceramic resistor ($15.00 for 2) and that would take care of the problem. I installed the blocks on both rear blinkers. After that they all (front and back) worked fine. The reason I wanted to bring this up to help others as I have seen this question posted on other sites. It may be purely coincidental that all the other problems happen at the same time but they also went away when I installed the resistors. Hope this helps others......

 

it was due to lack of draw from the LED lights .... they also sell a blinker relay that is for led lights ...

 

You wouldn't think that switching to LED's would cause such a problem, damn! Thanks for the tip.

 

ever replace the light bulbs in your house with LED, flip the switch but have to wait for the lights to come on? same concept, since every light in my house is like this haha

 

its due to the lack of AMPRAGE flow to the LED light .. they will run on like .2A and a filement type runs on like 1.8-2.5A depending on the size and such

 

Just add more LED's to increase the draw. It worked on an 85 F-250 I had. It didn't have all the other computer problems you had since it was older. The extra draw did make the signals work properly again.