I have a 97 - F150 that had a turn signal problem. Blinkers worked OK for lane change but when fully engaged they were intermittent and when malfunctioning the rear blinkers blinked fast and no blinking in front. Took the MFS apart and cleaned it. The first time I put it back together the high beams stayed on. Took it back apart and saw the error of my ways or I so thought. But now, no low beams and interior lights stay on (they go out after the 40 minute timer times out); blinkers and emergency flashers and high beams are OK. As a precaution, I disconnected battery when removing MFS and did not reconnect the battery until I re-connected the MFS. Checked fuses anyway and they are OK. Most certainly seems to be something I did wrong with MFS but I have no idea what. I did have trouble putting it back together but I feel that I did get it right. Suggestions?

 

just before anyone else does it. Have you checked the blinker fluid level?

 

Sounds like it is damaged, and now needs to be replaced.

You have nothing to loose, maybe take it back apart again, and see if something is wrong, but I would just replace it at this point.