Guys, I'm having a turn signal issue with my '02 F-250 that started this morning out of the blue. Seems that when the signal switch is set for a right hand turn and the brakes are applied, the signal will then become solid, not flash, and then blow the fuse. Evedently something with the brake light circuit is overloading the turn signal circuit and not canceling when the turn signal is activated.

Here are a couple of things I have tried to narrow down the culprit.

1) Left turn signal works fine regardless if the brake lights are operating.
2) Brake light circuit operates fine by itself.
3) Right turn signal works fine but there seems to be a back-feed of power causing the center third brake light as well as the left side rear brake light to flash in unison. If brake lights are then activated, the flash stops and becomes constant thus blowing the fuse.
4) Emergency Hazzard lights work perfect but the center third brake light again flashes as well which reverts back to some type of back-feed of power. Also, if brake lights come on, flashing turns to constant light and then blows the fuse again.

I guess my question is,. does this seem like the multifunction switch needs replacing or could this be a relay issue of some sort? I don' think its a ground issue simply because the left turn signal circuit as well as the center brake light circuit are both being breeched when the right turn signal is activated. Your thoughts?

Thanks

Jake
2002 F-250 Super Duty 5.4 V8

 

Maybe a Light Board issue or MF Switch as u suggested (my .02)
Try pulling just the Rear bulb & check problem, if still present put Rear back in & pull just the Front bulb's then re-test....May get the problem narrowed to the Front or Rear (possibly Socket's or Bulb Filament blown & laying across other) & if u cant make it go away either way my guess would be that MF Switch.
Good Luck

 

Thanks King for the info but I'm still having issues. All bulbs good. Replaced multifunction switch. Checked brake light switch, all relays under hood and the flasher module itself. Looks as if I am going to have to dig deeper. Must be some type of harness chaffing going on in order for the circuits to cross into one another as well as fuse blowing unless there is something that i'm missing elsewhere.

Jake

 

Found the issue with my lights. After tearing into everything and having no luck, I decided to crawl underneith and follow the harness from the rear bumper up to the front firewall area. I found that the entire harness somehow got pinched between the top of the frame rail and the underside of the cab body by the driversdie footwell. The harness was torn open and three wires were exposed and shorting out against one another as well as the frame rail. Once I pulled the harness out from underneith the body, all electrical functions went back to normal operation. I cleaned up and rapped everything then sleaved the entire harness in a peice of hose plus wrapped it tight with zip ties. All is good.

Jake