Why don't my Turn signals work?
Asked by Bert Feb 04, 2018 at 10:29 AM about the 2003 Ford F-150 XL Extended Cab LB
Question type: Maintenance & Repair
My turn signals have not been working, although my hazards are working. I
replaced the multifunction switch, the flasher relay and the ignition switch, as
well as checking all the associated relays and fuses.
6 Answers
I know in past I could bypass the multifunction switch, just for testing, and use jumper wire on the proper wire colors. I could make them turn signals dance. When you had the multifunction switch out, you should have tried that test, where applicable? bbbind.com should have wiring diagrams for your turn signal, so you can see wire colors. You might be able to get at wire harness, under the dash, where it goes into steering column, find the proper color wire for turn signal, left or right, activated, key on. Use a test lite on the wire, the test lite will usually flash. If nothing the problem is before the test point. Just a thought.
I would, as oilyspill said, use a test light on the input, then after leaving the multifunction switch. I would assume that the same fuse for the brake lights also protects the turn signals, since they both use the same filament. A wiring diagram here would be a plus, as you can trace it right down. Also check the grounds on and around your rear brake lamp(s). I have had nightmares with loose/bad grounds causing some really weird problems.
If the diagram is correct, as you can see, the flasher relay has two voltage circuits, bottom, in the diagram, one is for turn, the other is for flasher. The blue wire is turn. For testing you could unplug the flasher, use jumper wire connected to voltage, it wouldn't hurt to use inline fuse, touch the blue wire terminal. Operate the turn switch right or left, shouldn't need the key. The lamps in the correct direction should lite up. They won't flash because the flasher isn't hooked up. If the lamps at least lite up, that tells you something.
You have two fuse boxs one under dash one under hood check both,if brake liters (both) work your turn switch is ok