replace flaher unit it should also be in the fuse box or close buy it is a little silver box about 1inchx1/2inch where is the flasher unit in the fuse box?
Could be the bulbs or the fuses or the flashers or the signal switch assembly
The signals and the emergency flashers have separate circuits, separate fuses, separate flasher relays. Start with checking the fuses, the bulbs, the signal flasher relay and wiring and if it still doesn't work it may be the signal switch is bad.
One of the reasons why you may not have turn signals or flashers on the left side of your 1998 Ford Explorer if all the bulbs and sockets are good is you may have a blown fuse. Try replacing the light fuses or visiting an auto parts store to test the fuse to see if it is bad.
Check under the hood near the battery, there should be a black rectangular box with a lid that flips open. This is the power distrobution box. Your relays will be in there.
it is the relay, change it, it is the hazard button, the one with the red triangle.
turn signals and emerg flashers work off a flasher can. go to any auto store and buy a new one they are cheap and easy to replace
I would check the switch inside the steering column.
black box under hood leftside firewall
Try replacing the hazard flasher. If that does not work, double-check to see that you have the proper bulbs and fuses installed for the brake lamp circuit.
Probably the turn signal flasher
Try checking the turn signal flasher. Not to be confused with the hazard flasher.
Two separate flasher relays, one for the signals and one for the hazards. They are both located behind the plastic lower dash panel aprox under the radio. The lower panel must be removed to gain access to the flashers. Be sure to check the fuses and bulbs also.