From the service manual:
ADJUSTMENT - PARKING BRAKE
NOTE: Tension adjustment is only necessary when
the tensioner, or a cable has been replaced or disconnected
for service. When adjustment is necessary,
perform adjustment only as described in the
following procedure. This is necessary to avoid
faulty park brake operation.
(1) Raise vehicle.
(2) Fully back off cable tensioner adjusting nut at
equalizer to create slack in cables.
(3) Remove rear wheel/tire assemblies. Remove
brake calipers and rotors.
(4) Verify park brakes are in good condition and
(5) Verify park brake cables operate freely and are
not binding, or seized.
(6) Check park brake shoe adjustment.
(7) Reinstall rotors and make sure rotors turn
(8) Reinstall brake calipers. Tighten guide pin
bolts to 41 n·m (30 ft.lbs.).
(9) Reinstall wheel/tire assemblies after brake
shoe adjustment is complete.
(10) Lower vehicle enough for access to park brake
foot pedal. Fully apply park brakes.
NOTE: Leave park brakes applied until adjustment
(11) Raise vehicle again.
(12) Mark tensioner rod 6.35 mm (1/4 in.) from
edge of tensioner bracket (Fig. 100).
(13) Tighten adjusting nut at equalizer until mark
on tensioner rod moves into alignment with tensioner
CAUTION: Do not loosen, or tighten the tensioner
adjusting nut for any reason after completing
(14) Lower vehicle until rear wheels are 15-20 cm
(6-8 in.) off shop floor.
(15) Release park brake foot pedal and verify that
rear wheels rotate freely without drag. Verify pedal
returns to fully released position.
(16) Lower the vehicle.
You probably have worn parking brake shoes or a stretched or broken cable. Normally the brake system doesnt need regular adjustment unless something is broken or replaced.