Hazard signal and horn do not work on my 91 Toyota Celica Gt.

You have a body control module problem, more then likely . The BCM turns the turn signal on an off. Have a scan tool hooked up (a profesional grade scan tool ) One that can read codes in the BCM.

Turn Signal Lamps
The STOP/TURN/HAZARD fuse in the instrument panel (I/P) fuse block supplies battery positive voltage to the body control module (BCM) for the turn signal lamps. When the turn switch is placed in the LEFT TURN or RIGHT TURN position, ground is applied from G202 through the turn switch, to the turn signal switch signal circuit and to the BCM. The BCM then applies battery positive voltage to front and rear turn signal lamps supply voltage circuits. The left front turn signal lamp is grounded at G100, right front at G101, left rear at G301 and the right rear is at G302.


DTC B3948 Left Front Turn Signal Circuit

try fuses, first, for 10cents.
first know how it works.
then diagnose it.
saves $$$$

1998 last year of ZJ jeeps.
FSM book, open to chapter 8w.
go to page on ext. lamps turn/haz
page 52 (ive posted the free book 100s of times, no more)

haz ok, truns dead on 4 corners
does the cluster flash when turns dead? on corners 4.??>?>?>
the 2 fuses are F13 and F6 in the JB (cab box = JB)

the cluster has 2 lamps, left and right.
if cluster is dead, that is a bad switch

this is how it works.
can be a bad connection at (see small arrow red/)/?

When the turn signals quit working pull up , down , front to back an back to front on the turn signal switch handle . Do they work when doing this ? Pontiac had bad switch . The power for the turn signals goes through the flasher / hazard module . Could be the switch or the module.
The HAZARD LPS fuse in the left hand instrument panel (LH IP) junction block supplies battery positive voltage to the flasher module, which is part of the hazard switch assembly. The TURN LPS fuse in the LH IP junction block supplies ignition positive voltage to the flasher module. The turn signal lamps may only be activated with the ignition switch in the ON position. When the turn signal switch is placed in either the left or right position, current flow is from the flasher module's output to the turn signal switch assembly. The flasher module then sends an on-off voltage signal to either the left or right turn signals and their instrument panel cluster (IPC) indicator. When the hazard switch is pressed, all the turn signal lamps will flash including both IPC turn signal indicators.

haz ok. , both left and right bLINK FAIL?
that means the lamps are ok and wires to them,
on most cars, the blinkers have their own fuse.
like all electric fails, check fuses first.
always.
why buy parts guessing, $150 combo switch for a 10cent fuse?
first diagnose it , then buy parts. and save money.
heck try a repair shop, they will diagnose it cheap.
ill now look up your cars blink wiring.

the dome fuse runs the interior lamps.

horn, runs hazards. (tricky no.)>?
there is a Small fuse. Name small, (yes odd )
the back fuse must be good too, as it feeds the turn/haz relay
yes there is a relay here.
recap
horn, small, back FUSES, and FLASH relay must be good.
seem the flasher is bad.
see here at ?

page 1 of 2.(part)

from necessity to place a horn where the noise has the least restriction to the outside most horns are located behind the front grill /panel around the radiator area

most likely a faulty relay is all... fix that and you'll be fine, they tend to speed up to let you know that they're on their way out.

Check the FLASHER unit; the turn signal flasher is mounted in a clip on the right side of the steering column support bracket. The hazard flasher is located in the component center, under the instrument panel, on the right side. Replace the flasher by unplugging the old one and plugging in the new one.

Hazard flasher -->> The Flasher is located: Front seating area, passenger side, under dash, below glove compartment, mounted in fuse panel

Turn signal -->> The Flasher is located: Front seating area, driver side, under dash, mounted on passenger side of steering column

Good luck (remember comment and rated this).

you may check to see if your hazard light switch is disconnected or loose; if the hazard switch is not plugged in, both your hazards and turn signals will not operate

If the right side signals are working properly and you can hear the signal flasher clicking when the right side signals are selected, the flasher is not the problem. Its more likely you have a short to ground in the left side wiring somewhere.

Have you checked the fuses?  1 fuse panel in the driver side area of the car, and there may be 1 under the hood as well (usually near the battery).