Service Manual User Manual

Electrical System
10-61
Model 3606 • Origin 10/99
a. Parking Brake Switch Removal
1. Disconnect the negative (-) battery cable at the
negative battery terminal (Fig. 10– 62).
2. Carefully pry the parking brake switch and wiring out
of the mounting hole in the switch bezel (Fig. 10– 63).
3. Label and disconnect the wiring from the parking
brake switch. Remove the switch from the vehicle.
b. Parking Brake Switch Disassembly
DO NOT disassemble the parking brake switch. Replace
a defective or faulty switch with a new one.
c. Parking Brake Switch
Inspection and Replacement
Inspect the switch terminals for continuity and shorting in
both the engaged and disengaged positions. Replace a
defective or faulty switch with a new one.
d. Parking Brake Switch Installation and Testing
1. Route the wiring from the dash through the bezel,
then connect the wiring to the parking brake switch
as labeled during switch removal.
2. Properly position the "P" on the switch, then press or
"snap" the switch into place in the bezel.
3. Connect the negative (-) battery cable to its battery
terminal (Fig. 10– 65).
4. Clear the area around the vehicle of personnel and
any obstructions to vehicle travel.
5. Start the engine, engage the park lock switch, place
the travel select lever in FORWARD (F) or REVERSE
(R) and second gear and apply full throttle. The
vehicle should remain motionless in both FORWARD
and REVERSE positions.
Figure 10– 65. Connect the negative (-) battery cable
at the negative (-) battery terminal.
6. To test for proper parking brake switch
disengagement, firmly depress the service brake
pedal, disengage the park lock switch, place the
travel select lever in either forward or reverse and in
first gear, and slowly press the throttle pedal while
releasing the service brake pedal. The park brake
should release and the vehicle should travel freely.
Note: The park brake indicator on the operators display
panel must illuminate when the park brake switch is
engaged, and not illuminate when the park brake switch
is disengaged.
10.8.9 Service Brake Switch
The service brake switch (Fig. 10– 66) is located above
the service brake pedal, inserted through a mount hole in
the cab crossmember weldment and connected to a wir-
ing harness lead. A nut threads onto the service brake
switch to secure it to the crossmember.
Figure 10– 66.
The service brake switch is located
above the service brake pedal
.
The service brake switch is a spring-loaded switch that
senses movement along the service brake pedal arm.
When the brake pedal is pressed and the brake pedal
arm begins to move through its arc, the spring within the
switch allows internal contacts to close an electrical con-
nection. The service brake switch circuit is also spliced
into the park brake and Stabil-TRAK circuits.
Service Brake Switch Replacement
If the service brake switch (Fig. 10– 66) is suspect,
remove the switch. Remove the jam nut, then dislodge
the switch from the crossmember and unplug the har-
ness connector. Remove the switch from the vehicle and
test the switch for continuity and shorting. Replace a
defective or faulty switch with a new one.
When installing a switch, make sure that the brake pedal
does not actuate the brakes, and that the rubber cap on
the switch is securely threaded onto the mounting stem.
Adjust the jam nut so that the switch plunger is pushed
up into the switch is at least 1/4” (6,35 mm).
OS1040
Auxiliary
Function
Manifold
Park Brake
Solenoids
Negative (-)
Terminal
MS1810
Service
Brake
Switch
Plunger
Depressed at
least 1/4”
(6,35 mm)