Brake Warning Indicator Switch: The brake
warning indicator switch is a fluid level sending
switch. The CAB sends out a 12 volt signal to the
switch. The switch has a 1,000 ohm resistor inside
of it. This resistor is used for diagnostic purposes.
Normal voltage is about 2.3 volts. If the switch is
disconnected the resistor will be pulled out of the
circuit and the CAB will sense voltage at about 5
volts. If the fluid level becomes too low or the circuit
is shorted to ground, the voltage will be about 0
volts. Any fault condition will illuminate the red
brake warning indicator and the specific fault can
be read on the DRBIII
t
.
3.2
ADJUSTABLE PEDALS SYSTEM
DESCRIPTION
GENERAL
The Adjustable Pedals System (APS) is designed to
enable the fore and aft repositioning of the brake and
accelerator pedals. This results in improved ergo-
nomics in relation to the steering wheel for taller and
shorter drivers. Being able to adjust the pedal posi-
tions also allows the driver to set steering wheel tilt
and seat position to the most comfortable position.
The position of the brake and accelerator pedals can
be adjusted without compromising safety or comfort
in actuating the pedals. Repositioning the pedals
does not change the effort required for actuation.
Change of pedal position is accomplished by
means of a motor driven screw. Operating the
adjustable pedal switch activates the pedal drive
motor. The pedal drive motor turns a screw that
changes the position of the brake and accelerator
pedals. The pedal can be moved rearward (closer to
the driver) or forward (away from driver). The
brake pedal is moved on its activating lever to a
position where the driver feels most comfortable.
The accelerator pedal is moved at the same time
and the same distance as the brake pedal. The
accelerator pedal adjustment screw is turned by a
flexible shaft slaved off the brake adjustment screw.
Neither the pedal drive motor nor drive mecha-
nism are subject to the mechanical stress of brake
or accelerator application.
SYSTEM FEATURES
•
Range of Adjustment
The pedals may be adjusted up to 3 in. (75 mm)
•
Pedal Adjustment Speed
0.5 in./sec (12.5 mm/sec)
•
Pedal Adjustment Inhibitors
Pedal adjustment is inhibited when the vehicle is
in reverse or when cruise control is activated.
•
Memory
An optional memory feature is available. This
allows storing of one or two preferred pedal
positions in the Adjustable Pedal Module (APM).
A preferred position can be stored and recalled
using the door-mounted switches.
The door-mounted switches activate the Driver
Door Module (DDM). The DDM instructs the
APM via the PCI bus to store the current pedal
position.
A stored pedal position can be recalled (but not
stored) using the Remote Keyless Entry (RKE).
•
Adjustable Pedal Feedback Message
The
Electronic
Vehicle
Information
Center
(EVIC) will display a message when the APS is
disabled. ie: “Adjustable Pedal Disabled — Cruise
Control Engaged” or “Adjustable Pedal Disabled
— Vehicle in Reverse”.
•
Damage Prevention
Foot pressure or debris can stall pedal adjust-
ment. In order to avoid damage to system compo-
nents during pedal adjustment, the APM will
monitor pedal position sensor voltage. If the APM
does not detect expected voltage change within
1.5 seconds, it will cut power to the adjustable
pedal motor.
3.3
DIAGNOSTIC TROUBLE CODES
The vehicle electronic system modules may re-
port any of several diagnostic trouble codes (DTC)s.
The possible DTCs for the ABS and Adjustable
Pedals System are listed in the table of contents.
Diagnostic trouble codes are retained in memory
until erased using the DRB, or automatically erased
after 255 key cycles or 3,500 miles.
3.3.1
ABS INITIALIZATION
System initialization starts when the key is
turned to ‘‘run’’. At this point, the CAB performs a
complete self-check of all electrical components in
the antilock brake systems.
At 20 km/h (12 mph) a dynamic test may be
performed. If the brake lamp switch is activated the
test will be run at 40 km/h (24 mph) regardless of
the brake lamp switch state. This will momentarily
run the pump/motor. If during the dynamic test, the
driver has his/her foot on the brake pedal, he/she
may feel the test through brake pedal pulsations.
This is a normal condition.
If any component causes a diagnostic trouble code
during system initialization or dynamic check, the
CAB will illuminate the ABS warning lamp.
3.3.2
DIAGNOSTIC MODE
For a Mark 20 system to enter a diagnostic mode,
vehicle speed must be below 10 km/h (6 mph) and
no ABS condition present. If vehicle speed is not
below 10 km/h (6 mph), a ‘‘No Response’’ message
4
GENERAL INFORMATION
