1998 Taurus turn, hazard lights and power mirrors don't work

Doesn't have one , the BCM - body control module is in charge of flashing the turn signals & hazard lights.

Turn Signal/Hazard Lamps
When the turn signal switch is placed in either the left or right position, a ground signal is completed from the turn signal switch to the BCM. When the hazard flasher switch is activated, a ground signal is completed from the turn signal/hazard switch to the BCM. The BCM then sends an ON-OFF voltage signal through the fuses to the appropriate turn signal and side repeater (export only) lamps or to all of the turn signal fuses for hazard operation. The driver door switch and passenger door switch also receive voltage from the BCM turn signal supply voltage circuits for the mirror turn signals. The door switches have no function or control of the mirror turn signals other than a pass through connection for the circuits. The audio chime is also activated when the turn signals are ON. The instrument panel cluster (IPC) receives the signals to activate the turn signal indicators over the GMLAN serial data system. When the hazard switch is pressed, all turn signal lamps will flash including both IPC turn indicators.
On certain export vehicles, the auxiliary body control module (XBCM) controls and supplies voltage for all of the trailer lighting functions.
Hooking up a professional grade scan tool an checking for DTC'S - diagnostic trouble codes in the BCM is the first step in finding the problem .

You might possibly have a bad flasher module.

I can almost 100% guaranty the turn signal switch is the problem. Power for the brake lights starts at the brake switch. power then splits from there and the third brake light gets power directly from the brake switch. Since the turn signal and the brake lights are on the same bulb power for the brake lights is routed through the turn signal switch. the switch depending on what position it is in will allow brake power or turn signal power to there respective left or right brake/turn bulbs.

If you hold your foot on the brake pedal and wiggle the turn signal and or play with the hazard switch the brake lights will almost always intermittently start to work. this will confirm a bad turn signal switch which is pretty common on GM vehicle with this style setup.

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More likely that the turn signal switch assembly is bad.Have someone watch the tailights(or use a large mirror) to see if the bright tailight filaments come on with the brake pedal held down while you wiggle the hazard light switch.

The hazard switch gets power from the horn fuse which is hot all the time, and from the turn signal fuse which is hot when the key switch is on. The turn signal switch gets power from the hazard switch and both use the same flasher.
So if the turn signals work but the hazard switch does not power the lights, and both fuses have power, I would say the problem is inside the hazard switch.

SOUNDS TO ME LIKE WHATS CALLED BY FORD AS THE MUTIFUNCTION SWITCH THAT HAS GONE BAD. IT WILL NOT SHOW ON ANY SCAN TOOL, SO FORGET THAT ACTION, I HAVE SEEN THIS OCCUR WITH MANY FORDS OVER MY 30+ YEARS OF WORKING ON JUST FORD PRODUCTS!!!

Check the fuse/relay panel for a blown fuse/relay. Also look at the turn signal flasher and the four way flasher located in fuse/relay panel for problem. If the fuses are good replace the flashers to correct the problem. Hope this will help you.

sounds like you have a number of problems.
a. hazard lights and no head lamp dimming and no turn indicator, most likely the multi function switch has failed. but check the bulbs first.
b. head lamp bulb is burnt
c.side mirror switch is disconected or has failed

hazard switch try in out alot fast may fix or spay with co cleaner in side switch

the switches in the steering wheel