1.) Remove the 3 screws from the bottom of the plastic cover for the steering shaft and ignition switch. These are very long screws and require a lot of turning to get them out.
2.) Disconnect the wiring connectors from the turn signal, taking care not to dislodge any of the wires in the plastic shell.
3.) Remove the two screws from the mount that secures the turn/multifunction switch to the steering column mount. These may be tamper proof torx screws, which will require a torx bit that you can get from the auto parts store.
To reinstall, reverse the order.
Tamper Proof Torx bit set:
Advanced auto Parts Part No. AC571/W1386
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Multifunction turn signal switch:
Before you think about replacing the multifunction switch with one from the junkyard, here's some things to be aware of...
The problem is more common in GT models because they had fog lights on the same power wiring as the headlights. Ford undersized the wire and that caused problems.
A word of caution about multifunction switches is in order here. The multifunction switch (high/low beam, wiper, turn signals) are different for different years. 87-98 will work in any 87-89 car. The 90-93 switches only work in 90-93 cars. You can't put an early model switch in a late model car, nor can you put a late model switch in an early car.
Supposedly you can move the pins around to make the switches work in model years that are different from the car the switch came out of. I cannot verify that and haven’t tried it.
Other possible problem sources for the turn signal & headlight malfunction are the ignition switch, multifunction switch and the plastic shell that holds the turn signal wiring connector pins.
The following diagram is for 87-89 model cars.
Turn signal switch wiring:
