wheel MERCEDES-BENZ SPRINTER 2006 Owner's Manual

TEST ACTION APPLICABILITY
5 With the DRBIIIt, record and erase all DTC's from all Airbag modules.
If equipped with Passenger Airbag On - Off switch, read the DTC's in all switch
positions.
If any ACTIVE codes are present they must be resolved before diagnosing any stored
codes.
WARNING: TO AVOID PERSONAL INJURY OR DEATH, TURN THE IGNI-
TION OFF, DISCONNECT THE BATTERY AND WAIT TWO MINUTES BE-
FORE PROCEEDING.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Look for chaffed, pierced, pinched, or partially broken wires and broken, bent, pushed
out, spread, corroded, or contaminated terminals.
The following additional checks may assist you in identifying a possible intermittent
problem.
Reconnect any disconnected components and harness connector.
WARNING: TO AVOID PERSONAL INJURY OR DEATH, TURN THE IGNI-
TION ON, THEN RECONNECT THE BATTERY.
With the DRBIIItmonitor active codes as you work through the following steps.
WARNING: TO AVOID PERSONAL INJURY OR DEATH, MAINTAIN A SAFE
DISTANCE FROM ALL AIRBAGS WHILE PERFORMING THE FOLLOWING
STEPS.
Wiggle the wiring harness and connectors of the related airbag circuit or component.
If codes are related to the Driver circuits, rotate the steering wheel from stop to stop.
You have just attempted to simulate the condition that initially set the trouble code
message.
Did the DTC become active?All
Ye s!Select appropriate symptom from Symptom List.
No!No problem found at this time. Erase all codes before returning
vehicle to customer.
64
AIRBAG
PASSENGER SQUIB 1 SHORT TO BATTERY ÐContinued

TEST ACTION APPLICABILITY
5 With the DRBIIIt, record and erase all DTC's from all Airbag modules.
If equipped with Passenger Airbag On - Off switch, read the DTC's in all switch
positions.
If any ACTIVE codes are present they must be resolved before diagnosing any stored
codes.
WARNING: TO AVOID PERSONAL INJURY OR DEATH, TURN THE IGNI-
TION OFF, DISCONNECT THE BATTERY AND WAIT TWO MINUTES BE-
FORE PROCEEDING.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Look for chaffed, pierced, pinched, or partially broken wires and broken, bent, pushed
out, spread, corroded, or contaminated terminals.
The following additional checks may assist you in identifying a possible intermittent
problem.
Reconnect any disconnected components and harness connector.
WARNING: TO AVOID PERSONAL INJURY OR DEATH, TURN THE IGNI-
TION ON, THEN RECONNECT THE BATTERY.
With the DRBIIItmonitor active codes as you work through the following steps.
WARNING: TO AVOID PERSONAL INJURY OR DEATH, MAINTAIN A SAFE
DISTANCE FROM ALL AIRBAGS WHILE PERFORMING THE FOLLOWING
STEPS.
Wiggle the wiring harness and connectors of the related airbag circuit or component.
If codes are related to the Driver circuits, rotate the steering wheel from stop to stop.
You have just attempted to simulate the condition that initially set the trouble code
message.
Did the DTC become active?All
Ye s!Select appropriate symptom from Symptom List.
No!No problem found at this time. Erase all codes before returning
vehicle to customer.
67
AIRBAG
PASSENGER SQUIB 1 SHORT TO GROUND ÐContinued

Verification Tests
ABS VERIFICATION TEST - VER 1 APPLICABILITY
1. Turn the ignition off.
2. Connect all previously disconnected components and connectors.
3. Ensure all accessories are turned off and the battery is fully charged.
4. Ensure that the Ignition is on, and with the DRBIII, erase all Diagnostic Trouble Codes from
ALL modules. Start the engine and allow it to run for 2 minutes and fully operate the system
that was malfunctioning.
5. Turn the ignition off and wait 5 seconds. Turn the ignition on and using the DRBIII, read
DTC's from ALL modules.
6. If any Diagnostic Trouble Codes are present, return to Symptom list and troubleshoot new
or recurring symptom.
7. NOTE: If the CAB/HCU was replaced, ensure the CAB has been initialized
8. NOTE: If the SKREEM or ECM was replaced, refer to the service information for
proper programming procedures.
9. NOTE: For Sensor Circuit/Signal and Pump Motor faults, the CAB must sense all 4
wheels at 12 km/h (8 mph) before it will extinguish the ABS Indicator.
10. If there are no DTC's present after turning ignition on, road test the vehicle for at least 5
minutes. Perform several antilock braking stops.
11. CAUTION: Ensure braking capability is available before road testing.
12. Again, with the DRBIIItread DTC's. If any DTC's are present, return to Symptom list.
13. If there are no Diagnostic Trouble Codes (DTC's) present, and the customer's concern can
no longer be duplicated, the repair is complete.
Are any DTC's present or is the original concern still present?All
Ye s!Repair is not complete, refer to appropriate symptom.
No!Repair is complete.
AIRBAG VERIFICATION TEST - VER 1 APPLICABILITY
1. Remove any special tools or jumper wires and reconnect all previously disconnected
components - except the Battery.
2. WARNING: TO AVOID PERSONAL INJURY OR DEATH, TURN THE IGNITION ON,
THEN RECONNECT THE BATTERY.
3. Connect the DRBIIItto the Data Link Connector - use the most current software available.
4. Use the DRBIIItand erase the stored codes in all airbag system modules.
5. Turn the ignition off, and wait 15 seconds, then turn the ignition on.
6. Wait one minute, and read active codes and if there are none present read the stored codes.
7. Note: If equipped with Airbag On - Off switch, read the DTC's in all switch positions.
8. Note: Read the DTC's in all airbag system related modules.
9. If the DRBIIItshows any active or stored codes, return to the Symptom list and follow path
specified for that trouble code. If no active or stored codes are present, the repair is complete.
Are any DTC's present or is the original condition still present?All
YES
Repair is not complete, refer to appropriate symptom list.
NO
Repair is complete.
244
VERIFICATION TESTS

CLOCKSPRING C2 - YELLOWCAV CIRCUIT FUNCTION
1 20VT DRIVER AIRBAG SQUIB 1 LINE 1
2 20DG DRIVER AIRBAG SQUIB 1 LINE 2
CONTROLLER ANTILOCK BRAKECAV CIRCUIT FUNCTION
1 12BR GROUND
2 12RD FUSED B(+)
3- -
4- -
5 14BR GROUND
6 14RD FUSED B(+)
7- -
8 20BK/DG SENSOR SIGNAL
9 20YL/WT SENSOR SIGNAL
10 20YL/RD SENSOR SIGNAL
11 18BL/BK K-ABS/SHIFTER ASSEMBLY
12 18BK LEFT FRONT WHEEL SPEED SENSOR (+)
13 - -
14 20WT LEFT REAR WHEEL SPEED SENSOR (+)
15 18BR RIGHT FRONT WHEEL SPEED SENSOR (-)
16 18BK RIGHT FRONT WHEEL SPEED SENSOR (+)
17 - -
18 - -
19 - -
20 20WT BRAKE SWITCH OUTPUT
21 20BR GROUND
22 - -
23 18BK/RD FUSED OPTIONAL EQUIPMENT RELAY OUTPUT
24 20DG/WT CAN C BUS (+)
25 20BR SENSOR GROUND
26 20WT/GY BRAKE PRESSURE SENSOR SIGNAL
27 18BK/BL TCS SWITCH (ASR) SENSE
28 18BR LEFT FRONT WHEEL SPEED SENSOR (-)
29 20BR LEFT REAR WHEEL SPEED SENSOR (-)
30 20BR RIGHT REAR WHEEL SPEED SENSOR (-)
31 20YL RIGHT REAR WHEEL SPEED SENSOR (+)
32 18BK/RD BRAKE LAMP SWITCH OUTPUT
33 - -
34 - -
35 - -
36 - -
37 - -
38 - -
39 20RD/BL POWER INPUT
40 20DG CAN C BUS (-)
41 20DG/YL SENSOR SIGNAL
42 20WT/RD 5 VOLT SUPPLY
C
O
N
N
E
C
T
O
R
P
I
N
O
U
T
S
262
CONNECTOR PINOUTS

TABLE OF CONTENTS - Continued
DRIVE TEST COMPLETED SUCCESSFULLY................................28
DRIVE TEST ERROR....................................................29
INCORRECT TONE WHEEL..............................................32
LATERAL ACCELERATION SENSOR CIRCUIT...............................36
LATERAL ACCELERATION SENSOR IMPLAUSIBLE..........................36
LATERAL ACCELERATION SENSOR INTERNAL FAULT.......................39
LEFT FRONT INLET SOLENOID...........................................40
LEFT FRONT OUTLET SOLENOID.........................................40
LEFT FRONT, RIGHT REAR INLET SOLENOID..............................40
LEFT FRONT, RIGHT REAR OUTLET SOLENOID............................40
LEFT REAR INLET SOLENOID............................................40
LEFT REAR OUTLET SOLENOID..........................................40
RIGHT FRONT INLET SOLENOID..........................................40
RIGHT FRONT OUTLET SOLENOID.......................................40
RIGHT FRONT, LEFT REAR INLET SOLENOID..............................40
RIGHT FRONT, LEFT REAR OUTLET SOLENOID............................40
RIGHT REAR INLET SOLENOID...........................................40
RIGHT REAR OUTLET SOLENOID.........................................40
LEFT FRONT WHEEL SPEED SENSOR CIRCUIT............................43
LEFT REAR WHEEL SPEED SENSOR CIRCUIT..............................43
RIGHT FRONT WHEEL SPEED SENSOR CIRCUIT...........................43
RIGHT REAR WHEEL SPEED SENSOR CIRCUIT............................43
LEFT FRONT WHEEL SPEED SENSOR SIGNAL.............................46
LEFT REAR WHEEL SPEED SENSOR SIGNAL..............................46
RIGHT FRONT WHEEL SPEED SENSOR SIGNAL............................46
RIGHT REAR WHEEL SPEED SENSOR SIGNAL.............................46
WHEEL SPEED SENSOR SIGNAL ERROR..................................46
NO COMMUNICATION WITH BUS.........................................49
NO COMMUNICATION WITH ECM.........................................52
NO COMMUNICATION WITH IC...........................................54
PARAMETERIZATION ERROR............................................56
PUMP MOTOR.........................................................57
RELAY OUTPUT VOLTAGE...............................................60
SOLENOID RELAY......................................................63
STEERING ANGLE SENSOR CALIBRATION ERROR..........................65
STEERING ANGLE SENSOR GREATER THAN 720 DEGREES.................66
STEERING ANGLE SENSOR IMPLAUSIBLE CAN SIGNAL.....................68
STEERING ANGLE SENSOR IMPLAUSIBLE VALUE..........................70
STEERING ANGLE SENSOR IMPLAUSIBLE WHEEL SPEED...................72
STEERING ANGLE SENSOR INTERNAL FAULT..............................74
SYSTEM OVERVOLTAGE................................................75
SYSTEM UNDERVOLTAGE...............................................77
VERIFICATION TESTS
VERIFICATION TESTS...................................................79
8.0 COMPONENT LOCATIONS...............................................81
8.1DLC ± INDICATORS................................................81
8.2CAB ± WSS.......................................................82
ii

TABLE OF CONTENTS - Continued
9.0 CONNECTOR PINOUTS.................................................83
BRAKE FLUID LEVEL SWITCH............................................83
BRAKE LAMP SWITCH C1 (EXCEPT ESP)..................................83
BRAKE LAMP SWITCH C2 (EXCEPT ESP) - BLACK..........................83
CONTROLLER ANTILOCK BRAKE.........................................84
INSTRUMENT CLUSTER C2 - WHITE......................................85
STEERING ANGLE SENSOR..............................................85
TCS SWITCH (ASR) - BLACK.............................................85
WHEEL SPEED SENSOR-LEFT FRONT....................................85
WHEEL SPEED SENSOR-LEFT REAR......................................86
WHEEL SPEED SENSOR-RIGHT FRONT...................................86
WHEEL SPEED SENSOR-RIGHT REAR....................................86
10.0 SCHEMATIC DIAGRAMS.................................................87
10.1BOSCH 5.7 ANTILOCK BRAKE SYSTEM ± ABS.........................87
iii

1.0 INTRODUCTION
The procedures contained in this manual include
all the specifications, instructions, and graphics
needed to diagnose the Sprinter Chassis system
problems: Bosch 5.7 ABS/ESP/TCS (ASR) Braking
System. The diagnostics in this manual are based
on the failure condition or symptom being present
at time of diagnosis.
Please follow the recommendations below when
choosing your diagnostic path.
1. First make sure the DRBIIItis communicating
with the vehicle system being diagnosed. If the
DRBIIItdisplays a ``No Response'' condition, you
must diagnose that first.
2. Read DTC's (diagnostic trouble codes) with the
DRBIIIt.
3. If no DTC's are present, identify the customer
complaint.
4. Once the DTC or customer complaint is iden-
tified locate the matching test in the Table of
Contents and begin to diagnose the system.
All component location views are in Section 8.0.
All connector pinouts are in Section 9.0. All sche-
matics are in Section 10.0.
When repairs are required, refer to the appropri-
ate service manual for the proper removal and
repair procedure.
Diagnostic procedures change every year. New
diagnostic systems may be added; carryover sys-
tems maybe enhanced. READ THIS MANUAL BE-
FORE TRYING TO DIAGNOSE A VEHICLE DI-
AGNOSTIC TROUBLE CODE. It is recommended
that you review the entire manual to become famil-
iar with all new and changed diagnostic procedures.
This manual reflects many suggested changes
from readers of past issues. After using this man-
ual, if you have any comments or recommendations,
please fill out the form at the back of the manual
and mail it back.
1.1 SYSTEM COVERAGE
This diagnostic procedure manual covers the An-
tilock Braking System (ABS), the Electronic Stabil-
ity Program (ESP) and the Traction Control System
(TCS) found on the Sprinter.
1.2 SIX-STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the Antilock Brake Systems is done
in six basic steps:
²Verification of complaint
²Verification of any related symptoms
²Symptom analysis
²Problem isolation
²Repair of isolated problem
²Verification of proper operation
2.0 INDENTIFICATION OF
SYSTEM
The Bosch 5.7 system can be identified by the 42
way Controller Antilock Brake (CAB), Hydraulic
Control Unit (HCU) and Pump Motor being an
integral electronic/hydraulic unit mounted below
the Master Cylinder with four Wheel Speed Sen-
sors, one at each wheel.
Vehicles with the Traction Control System (TCS/
ASR) can be identified by the presence of the
Traction Control System Switch (TCCS) located on
the center instrument panel.
Vehicles with Electronic Stability Program (ESP)
can be identified by the presence of the Steering
Angle Sensor and the Lateral Acceleration/Yaw
Sensor.
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
3.1 ESP
The ESP system consists of the electronic control/
hydraulic unit, steering angle sensor, lateral
acceleration/yaw sensor and wheel speed sensors.
When the vehicle is in a turn, the ESP looks at the
steering wheel angle sensor value and monitors the
wheel speed of the inner and outer wheels to ensure
the values are plausible. The steering angle sensor
also measures the speed at which the steering
wheel is turned.
The ESP control module is very similar to the
ABS/ASR module. The ESP is comprised of several
other systems, namely theHBA, ABS, TCS (ASR),
EBDandFZRsystems.
3.2 ABS
The Controller Antilock Brake (CAB) is used to
monitor wheel speeds and modulates (controls) hy-
draulic pressure in each brake channel. The modu-
lated hydraulic pressure is used to prevent wheel
lock up during braking and maintain vehicle stabil-
ity. The CAB also provides a vehicle speed signal
(VSS) to the Electronic Control Module (ECM).
During a non-ABS stop, the system functions as a
standard braking system. The CAB uses special
sortware that monitors the wheel speed(s) and
when certain criteria are met, the software will
1
GENERAL INFORMATION

enable the HCU to perform the brake fluid manage-
ment control as the combination/proportioning
valves.
The Bosch 5.7 system uses the CAB/HCU/Pump
Motor to make an integral electronic/hydraulic unit
which shares data with other electronic modules on
the vehicle via the CAN C Bus network. To access
DTCs from the CAB, the DRBIIItuses the K-ABS
line located in the Data Link Connector (DLC).
3.3 BRAKE ASSIST SYSTEM (HBA)
The Brake Assist System (HBA) analyzes how
hard and fast the driver wants to brake. It monitors
the brake pressure via a pressure sensor. The
passenger car brake assist system uses a vacuum
booster solenoid. The Sprinter uses the hydraulic
control unit to develop the brake pressure.
3.4 TCS (ASR)
The primary function of the Traction Control System
is to reduce wheel slip and maintain traction at the
driven wheels when the road surfaces are slippery. The
Traction Control System reduces wheel slip by applying
the brake that has lost traction. The system is designed
to operate at speeds below 50 km/h (30 mph). The
engine's torque can be reduced by the ECM via the CAN
C Bus, if necessary. The TCS can be deactivated with
switch on the dash. The Traction Control System uses
the ABS to indicate spinning tires to enable the traction
control function. The TCS software is in the CAB.
The TCS (ASR) performs the following functions:
1. Engine power derate
2. Engine deceleration regulation. If the vehicle is
on a patch of ice, the simple action of releasing
the throttle is enough to cause the rear wheels to
slip. To avoid this, the throttle input is regulated
so power drops slowly instead of abruptly. The
engine power is reduced (decelerated) as neces-
sary.
3.5 ELECTRONIC BRAKE DISTRIBUTION
(EBD)
The system was enhanced and eliminates the
need for the ALB system (load sensing valve). All
ESP equipped models will not have ALB. The EBV
system self-adapts to operating conditions. It de-
tects the vehicle's payload when the vehicle starts
and pulls away. Based on the acceleration rate
when the vehicle first pulls away from a standstill,
the system is able to calculate the actual payload.
This is a rough estimate which is used initially.
Later on, the system gathers more precise informa-
tion by monitoring the brake pressure and wheel
speed and negative slip when the driver applies thebrakes. The system will then produce a more accu-
rate calculation of payload depending on brake
retardation. The adaptation is erased when the
ignition is switched off. A new adaptation will occur
on the next driving cycle. By default, the system
acts upon the vehicle as if in an unloaded condition
(safe mode).
Once a new driving cycle begins with the vehicle
in a fully loaded condition (without having gathered
more precise information) the system will detect
ABS actuation in the front wheels and will allow
enough pressure to be applied to the rear axle, to an
extent where the wheels are just about to lock up
(maximum braking possible).
The system calculates the braking force at the
front and rear axles. If the driver applies the brakes
gently and then realizes he needs to apply the
brakes further, the EBV allows the proper pressure
to be applied to the front and rear brakes.
The EBV also contains a feature called ªcorner
brake systemº (CBS) which operates when the ve-
hicle is braked while cornering to avoid a possible
oversteering condition. The EBV monitors the
wheel speed of both rear wheels to detect when the
vehicle is cornering and allows precise brake pres-
sure application to the front and rear brakes. Also
when the brakes are applied during cornering, the
outer wheels get more of the vehicle's weight while
the inner wheels get less weight and could lose
traction (wheel lock up). The EBV system splits the
pressure between left and right sides in addition to
front and rear brakes.
3.6 VEHICLE CONTROLLING (FZR)
Vehicle controlling (FZR)requires additional
sensors to operate. The term ESP refers to the
software of the system. The term FZR refers to the
system controller. The TCS (ASR) system requires
wheel speed sensors to monitor wheel slip and CAN
bus communications to regulate engine power. In
addition to these inputs, the vehicle controlling
(FZR) requires a steering angle sensor, and a lateral
acceleration/yaw rate sensor.
The ESP system does not take the vehicle load
into account. Instead, the coefficient of friction is
calculated in a 20 millisecond period, where the
controller measures the rate at which the wheel
speed is decelerated, as brake pressure is applied to
the wheel.
3.7 SYSTEM COMPONENTS
²Controller Antilock Brake (CAB)
²Hydraulic Control Unit (HCU)
²Pump Motor
2
GENERAL INFORMATION

²Four Wheel Speed Sensors/Tone Wheel assem-
blies
²ABS warning indicator
²TCS (ASR) event indicator
²TCS (ASR) warning indicator
²Steering Angle Sensor
²Lateral Acceleration/Yaw Rate Sensor
²Brake Pressure Sensor
²ESP event indicator
²Brake Fluid Level switch
²Brake Switch (BS)
²Brake Lamp Switch (BLS)
²TCS Switch (TCSS)
²K - ABS
²CAN C Bus
²Fuses, grounds, and wiring
3.7.1 ABS AND TCS (ASR) INDICATORS
This system is equipped with an ABS warning
indicator, TCS (ASR) warning indicator, and TCS
(ASR) event indicator to alert the driver of a
malfunction/event it has detected. The CAB can
request the illumination of the ABS warning indi-
cator, TCS (ASR) warning indicator, and TCS (ASR)
event indicator via CAN C BUS. The CAB controls
the ABS warning indicator by:
²Light steady during an initial test at the begin-
ning of an ignition cycle to function as a bulb
check
²Light steady when a system malfunction exists
(DTC)
²Light steady - If you have not met the speed
required to reset/retest the ABS components
The Instrument Cluster (IC) controls the indica-
tors. The Instrument Cluster transmits a message
over the CAN C Bus relating to diagnostics and
current lamp status for the ABS and TCS (ASR)
indicators. The CAB can control the operation of
TCS warning and TCS event indicators by:
²Both light steady with engine off and both go out
with engine running
²TCS warning indicator lights steady when a TCS
malfunction exists
²TCS event indicator will flash when TCS is in an
active event
3.7.2 CONTROLLER ANTILOCK BRAKE
(CAB)
The CAB is mounted directly to the Hydraulic
Control Unit (HCU) that includes a microprocessor
and twelve solenoids that control valves that con-trol brake pressure during antilock braking or trac-
tion control events. The CAB also has circuits that
monitor the following:
²Double brake switch outputs are monitored to
determine whether or not to prepare for possible
ABS braking
²Wheel Speed Sensors are monitored to determine
when a wheel is tending to lock up. The CAB will
operate the valves in the HCU to control braking
pressure during ABS braking
²Detect ABS system related problems and take
diagnostic action
²Able to execute self-tests and output control com-
mands
When equipped with Electronic Stability (ESP),
the CAB also monitors the following:
²The ESP looks at the Steering Angle Sensor value
and monitors the speed of the inner and outer
wheels to ensure that the values are plausible.
The Steering Angle Sensor also monitors the
speed that the steering wheel is turned.
²The Lateral Acceleration/Yaw Rate Sensor is con-
tained in one unit. The sensor measures side to
side (lateral) motion and rotational motion (how
fast the vehicle is turning).
²The ESP uses data from the Brake Pressure
Sensor to analyze how hard and fast that the
driver wants to brake.
3.7.3 HYDRAULIC CONTROL UNIT (HCU)
The HCU on the Bosch 5.7 has an integral valve
body for controlling the front and rear brakes.
Within the HCU are inlet, outlet, and shuttle
valves, to release brake pressure as required to
avoid wheel lockup, keeping the wheels rolling, and
maintain optimum deceleration with stability. The
Pump Motor is attached to the HCU which works
with the ABS and TCS and is controlled by the
CAB. The primary function is to provide extra
amount of fluid when needed.
3.7.4 SWITCHES/SENSORS
BRAKE SWITCH (BS):This switch prepares the
CAB for a possible antilock event. The CAB uses an
output state voltage from the BS when the brake
pedal is either released/depressed. The Fused Igni-
tion Switch Output circuit supplies 12 volts to the
BS. A released brake pedal will close the BS circuit
and the BS Output circuit supplies 12 volts to the
CAB. When the driver depresses the brake pedal,
the BS Output circuit voltage drops to 0 volts and
the CAB senses the brake pedal state. This tells the
CAB what position the brake pedal is currently in to
make an ABS event possible. When using the
DRBIIItin Inputs/Outputs, the BS and BLS will
3
GENERAL INFORMATION

read opposite switch states.Note: The BS and
BLS are in the same switch housing.
BRAKE LAMP SWITCH (BLS):This switch pre-
pares the CAB for a possible antilock event. The
CAB uses an output state voltage from the BLS
when the brake pedal is either depressed/released.
The Fused Ignition Switch Output circuit supplies
12 volts to the BLS. A depressed brake pedal will
close the BLS circuit and the BLS Output circuit
supplies 12 volts at the CAB. When the driver
releases the brake pedal, the BLS Output circuit
voltage drops to 0 volts and the CAB senses the
brake pedal state. This tells the CAB what position
the brake pedal is currently in to make an ABS
event possible. When using the DRBIIItin Inputs/
Outputs, the BS and BLS will read opposite switch
states.Note: The BS and BLS are in the same
switch housing.
TRACTION CONTROL SYSTEM SWITCH
(TCSS):This switch signals the CAB to either turn
ON or OFF the TCS. The driver can toggle the
TCSS, which receives 12 volts from the D (+) Relay
Output circuit. Depending on the position of the
TCSS, open or closed, the CAB receives the TCSS
state voltage on the TCS Switch Sense circuit.
When 12 volts are applied to the TCS Switch Sense
circuit, the TCS is OFF. When no voltage is present,
the TCS is ON.
WHEEL SPEED SENSORS AND TONE
WHEELS:The Bosch 5.7 system uses one passive
WSS on each wheel. The sensor measures the wheel
speed by monitoring a rotating tone wheel. As the
teeth of the tone wheel move through the magnetic
field of the sensor an AC voltage and amperage is
generated. This signal frequency increases or de-
creases proportionally to the speed of the wheel.
The CAB monitors this signal to check for a sudden
change in single or multiple wheel decelerations. If
the deceleration of one or more wheels is not within
a predetermined amount, the CAB takes control for
antilock action through the HCU. Each WSS has a
magnetic inductive pick up coil (WSS) that is
mounted to a fixed component. There is an air gap
between the tone wheel and the speed sensor as-
sembly. Diagnostically, the coils of the Wheel Speed
Sensors have the same amount of resistance. When
measured across the CAB harness connector termi-
nals, the resistance should be between 1100 - 1800
ohms. Refer to service manual for WSS replacement
and air gap specifications.
Correct ABS operation is dependent on Tone
Wheel speed signal from the WSS. The vehicle
wheels and tires should all be the same size and
type to get accurate signals. In addition, all tires
should be at recommended tire pressures.3.7.5 SELF TESTS
The system software includes several self tests
that are performed every time the ignition is turned
on and the vehicle is driven. Some of the self tests
occur immediately, while others occur under normal
driving conditions while not in antilock operation.
The CAB checks continuously for a missing or
erratic WSS signals/circuits, tone wheels, solenoids,
pump motor or solenoid relay by performing several
tests such as: dynamic, static, ohmic, voltage drop,
and timed response. If any component exhibits a
fault during testing, the CAB will request to illumi-
nate the ABS and TCS warning indicators.
As an additional check of the ESP system, a road
test procedure is available on the DRBIIIt. This
test should be carried out when any ESP component
is replaced in order to ensure proper function. Since
the wheel speed sensors are required inputs to the
ESP, this test should also be performed if the wheel
speed sensors are replaced.
First, the brakes are applied with the vehicle
stationary. Then, the vehicle is driven at approxi-
mately 6 MPH. The driver has to make left and
right turns, with a minimum 90 degree steering
turning angle. If the indicator lamp goes out, every-
thing is in order. If the lamp remains illuminated,
the DRBIIItwill display the fault codes that are
causing the test to fail. The road test function is set
in the ESP control module, and can only be deacti-
vated once there are no more fault codes detected.
The Steering Angle Sensor must be initialized. A
procedure is carried out using the DRBIIItto
ensure that the module detects the exact position of
the sensor. The sensor must be calibrated any time
wheel alignment is changed, the steering column is
removed and re-installed, or the sensor is replaced.
3.8 USING THE DRBIIIT
Refer to the DRBIIItuser 's guide for instructions
and assistance with reading diagnostic trouble
codes, erasing diagnostic trouble codes and other
DRBIIItfunctions.
3.9 DRBIIITERROR MESSAGES
Under normal operation, the DRBIIItwill dis-
play one of only two error messages:
Ð User-Requested WARM Boot or User-Requested
COLD Boot.
If the DRBIIItshould display any other error
message, record the entire display and call the
STAR Center for information and assistance. This
is a sample of such an error message display:
4
GENERAL INFORMATION