I have a 2003 F250 7.3L diesel with 128000 mileages. Engine works well but I am experiencing a lot of electrical problems. 1 - frog light come off with high beams not low beams 2 - electric mirrors not working 3 - passenger airbag key switch and indicator light on dash not working. 4 - today, the OD switch - ''off Light'' started flashing. The tranny would shift into and out of OD, but light remained flashing.

Normally the fog lights are on when the low beams are on, then turn off when the high beams are switched on. you prolly will have to rewire your fog lights . The wires are getting short and the fuses are getting bit weak.Replace the fuses under the hood and in the fuse panel. Also check the fog light bulbs and the head light switch.Check voltages at the dimmer switch under the dash. Also for power mirrors check the fuse under the side of mirror panel/socket.Check the voltages at the panel wires.It should show exact 12 volts if the wires are good.If not then there is short in wires.Also check the grounds wire.The one which is black in color in the wire harness under the dash. A self-diagnosis function is built into the electrical control system. Warning is indicated by the overdrive OFF indicator light.Note: Warning and diagnostic codes can be read only when the overdrive switch is ON. If OFF, the overdrive OFF light is lit continuously and will not blink.
Check "O/D Off" Indicator Light:
1. Turn the ignition switch ON.
2. The "O/D Off" light will come on when the O/D switch is placed at OFF.
3. When the O/D switch is set to ON, the "O/D Off" light should go out. If the "O/D Off" light flashes when the O/D switch is set to ON, the electronic control system is faulty.


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