sinister187

Been lurking around for a solution to my turn signal problem...

2003 F150 XLT. My turn signals (both right & left) when engaged cause the relay to make a continuous buzzing sound. While the relay is buzzing, the signals will not blink and the signal lights on the dash will not illuminate. I have replaced the relay and multifunction switch and the same problem exists. The hazards work perfectly. My next guess is to replace the multifunction switch harness but I want stop throwing money at guessing. haha.

Anyone encountered a problem like this and what was your solution? Any input is much appreciated. Thanks!

sinister187

Okay...So after some more investigation, I've found if the brake is applied and I slightly engage the turn signal (not all the way so it doesn't lock into position) I can get both turn signals to light up. Everything else, electronic wise, seems to be working properly.

I've read on other make/models where the ignition switch can be the culprit. Nobody has run into this problem eh?

ibd2328

iTrader: (2)

Take off your steering wheel shroud and use a DMM or light tester to check your MFS

sinister187

I replaced the MFS thinking that was the problem but it does the same thing with the new MFS as the old one.

ibd2328

iTrader: (2)

Have you changed flasher relays?

sinister187

There are 2 relays in the same housing unit, I replaced the larger one (blue). Could the smaller black relay also be an issue? Can anyone confirm?

Thx!!

sinister187

In case anyone is wondering about replacing their turn signal relay thought these pics might help. The relay housing is under the dash between radio and steering column. Easy way to find it is to turn your hazards on and follow the noise! Well, I guess that method only works if your relay is functional though





OEM relay is blue. The aftermarket one from AutoZone was black.