Signal Lights Not Working on a 2001 Ford F-250  

Question:

Expert Reply:

I do know that the 7-Way replacement connector # 118242 that we offer for the 2001 Ford F-250 light duty models will include the necessary relays and fuses for installation, so the flasher issue could very well be that you are missing a required fuse or relay. This would be something you could check with Ford.

Please note that the 118242 wiring harness is only a fit for the F-250 light duty models. If your vehicle is a Super Duty model and is equipped with a factory tow package, you would use plug-in 7-Way # 118243.

Did you hardwire the vehicle connector, or was it a plug-in installation? If you hardwired the connector to your vehicle, I would check the ground wire to make sure it is still firmly attached to a clean, metal surface.

If you used a plug-in application like part # 118242, I would use a circuit tester, part # PTW2993 if needed, to test the connectors into which the harness would plug, to see if there is actually power going to the factory connectors.

If you find that power is not going to your factory connectors, you would need to use a hardwire application like part # 18252. You would hardwire the 4-Way plug using the included circuit tester and quick splices. The wire colors would be as follows:

White: Ground wire, connected to a suitable grounding location.
Green: Right turn signal and brake, connected to the turn signal wire behind your right tail light assembly.
Yellow: Left turn signal and brake, connected to the turn signal wire behind the left tail light assembly.
Brown: Tail light wire, connected to the wire for running lights behind one of your tail light assemblies.

If you need a 7-Way plug, you would need to use an adapter such as part # 37185. The adapter would plug into the 4-Way plug you just installed, and you would need to connect the three additional wires. The additional wire functions would be:

White: Grond wire.
Blue: Electric brake wire, connected to the electric brake wire from a brake controller in the vehicle cab, if applicable.
Black: 12v power lead wire, connected to the vehicle positive battery terminal.
Purple: Reverse light wire, connected to the reverse light wire behind your tail light assembly. If your trailer does not have reverse lights, this wire could be tied up.

I have also included a link to some diagrams and information that should be helpful.

expert reply by: Sarah L

0

Jim

11/18/2025

Have a 2004 ford f250 super duty 4x4 Problem l am having is turn signal work then stop I bought a flasher relay looking under the dash where fuse box is saw a few relays in fuse panel looking for flasher relay my manual only specifies location number of the relays Flasher relay is it possible it could be in a another location

Jameson C.

11/18/2025

@Jim it should be above the OBD2 connector under the dash? Did you check there?