I would guess a bad multifunction switch would be to blame.

 

So easy/hard to replace? And how?

 

Real easy. I replaced mine due to the wipers not working... The only way my wipers would work was if I hit the turn signal.

You have to loosen the casing around it, then it should come off with 3 screws and the plug. Took no time at all.

Best bet is to get one with low miles at a wrecking yard. Mine came out of a 2005 Sable that was off the road since 2007. Showed up at the yard last year.

You can also take yours apart to clean. Connections get gummed up. 1996-2003 is able to be disassembled. Then just clean contacts with a q-tip and rubbing alcohol. Do a quick search.. there should be a thread on cleaning these out of that era of bulls.

I simply replaced as mine was not serviceable.

 

What years will fit mine? 99 Ford taurus se ohv?

 

I have had the problem with my '99 and just cleaning it did the trick.

http://www.taurusclub.com/wiki/index.php/M...Switch_Cleaning

 

I would stick with a 98/99. A 2000 may work but I need someone to confirm that. Lots was changed in 2001 with circuitry.

 

Check the forum topic finder and/or wiki for r&r instrs.

 

If you replace the switch with aftermarket should be ok. In the meantime you can pull the 30 amp fuse on the inside to stop that happening. (My current solution. Just have to put it back when it rains, and that's rare.)