Height Sensing Proportioning Valve-General Information; Brake Light Switch-Replacement - Jeep cherokee 1989 Owner's Manual

9-18
6 Position the pedal in the bracket and slide the pivot pin to the
right, making sure it passes through the pedal bushings, Install the nut
and tighten it to the specified torque.
7 Connect the booster pushrod to the brake pedal, inserting a new
bolt from the right side on models with a manual transmission and
from the left side on automatic transmission models (see illustration
15.3). Install new nuts and tighten them to the specified torques.
8 Connect the negative battery cable and test the brakes for proper
operation.
16 Height sensing proportioning valve
Note: Only the Comanche models are equipped with this valve.
The height sensing proportioning valve regulates hydraulic pres-
sure to the rear brakes in accordance with the amount of weight pre-
sent in the bed of the truck. When the bed is empty, pressure to the
rear brakes will be decreased to avoid locking up the wheels. When
the bed contains a load, the valve senses the lower ride height and al-
lows more hydraulic pressure to the rear brakes.
Due to the special tools, test equipment and skills required to di-
agnose and service the height sensing proportioning valve, it is not
recommended that the home mechanic attempt the procedures. If ser-
vicing the system becomes necessary, take the vehicle to a dealer ser-
vice department or other qualified repair shop.
Warning: Any suspension modifications that alter the distance be-
tween the rear axle and the frame (such as the installation of air shocks,
heavy duty springs or lift kits) will furnish the height sensing proportion-
ing valve with a false reading. This could lead to inadequate braking
characteristics, possibly resulting in an accident.
-
17
Brake light switch replacement
Refer to illustration 17.2
2 From under the dash, unplug the brake light switch electrical con-
nector and remove the pushrod bolt (pre-1991 models) or the retaining
clip (1991 and later models). Remove the brake light switch, noting the
positions of the bushings, spacers and sleeves (see accompanying il-
lustration and illustration 15.3).
3 Lubricate the switch bushings, spacers and sleeves with a light
coat of multi-purpose grease and position the switch against the brake
pedal, Install the pushrod bolt and nuts or retaining clip. On pre-1991
models, be sure to tighten the nuts to the torque listed in this Chap-
ter's Specifications.
4 Plug in the electrical connector and reconnect the battery.
The Motor Manual Guy
Chapter 9 Brakes
general information
5
later models, it is adjustable.
6
the brake pedal forward by hand and watch the switch plunger. It
should be fully extended at the point at which pedal freeplay is taken
up and brake application begins. A clearance of about 1/8-inch should
exist between the plunger and the pedal at this point.
7
operating, no adjustment is necessary. If the plunger doesn't fully ex-
tend and the clearance between the pedal and switch barrel is insuffi-
cient, adjust the switch.
8
as far as possible. The switch plunger barrel will "ratchet" to the rear in
its retaining clip to the correct position. Measure the plunger-to-pedal
clearance to make sure it's correct and verify that the brake lights are
still operating correctly. Warning: Make SURE the brake pedal returns
to its fully released position after adjustment. The switch can interfere
with full pedal return if it's too far forward, resulting in dragging brakes
caused by partial brake application.
DASH
PANEL
BRAKE PEDAL
(MAN. TRANS.)
17.2 Brake pedal and brake light switch mounting details
On pre-1991 models, the switch is not adjustable. On 1991 and
To check the switch adjustment on 1991 and later models, move
If the plunger-to-pedal clearance is correct and the brake lights are
To adjust the switch, grasp the brake pedal and pull it to the rear
SUPPORT
SWITCH
BRAKE PEDAL
(AUTO. TRANS.)
I