ABS MERCEDES-BENZ SPRINTER 2006 Owner's Manual

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

4.2.4 DRBIIITSAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRBIIITMULTIMETER IS DANGEROUS. IT
CAN EXPOSE YOU TO SERIOUS OR
POSSIBLE FATAL INJURY. CAREFULLY
READ AND UNDERSTAND THE CAUTIONS
AND THE SPECIFICATION LIMITS.
²Follow the vehicle manufacturer 's service speci-
fications at all times.
²Do not use the DRBIIItif it has been damaged.
²Do not use the test leads if the insulation is
damaged or if metal is exposed.
²To avoid electrical shock, do not touch the test
leads, tips, or the circuit being tested.
²Choose the proper range and function for the
measurement. Do not try voltage or current mea-
surements that may exceed the rated capacity.
²Do not exceed the limits shown in the table below:
FUNCTION INPUT LIMIT
Volts 0 - 500 peak volts AC
0 - 500 volts DC
Ohms (resistance)* 0 - 1.12 megaohms
Frequency Measured
Frequency Generated0-10kHz
Temperature -58 - +1100ÉF
-50 - +600ÉC
* Ohms cannot be measured if voltage is present.
Ohms can be measured only in a non-powered
circuit.
± Voltage between any terminal and ground
must not exceed 500v DC or 500v peak AC.
± Use caution when measuring voltage above
25v DC or 25v AC.
± Use the low current shunt to measure circuits
up to 10A. Use the high current clamp to
measure circuits exceeding 10A.
± When testing for the presence of voltage or
current, make sure the meter is functioning
correctly. Take a reading of a known voltage or
current before accepting a zero reading.
± When measuring current, connect the meter in
series with test load.
± When using the meter function, keep the
DRBIIItaway from spark plug or coil wires to
avoid measuring error from outside interfer-
ence.
4.3 WARNING
4.3.1 VEHICLE DAMAGE WARNINGS
Before disconnecting any control module, make
sure the ignition is ``off ''. Failure to do so could
damage the module.
When testing voltage or continuity at any control
module, use the terminal side (not the wire end) of
the connector. Do not probe a wire through the
insulation; this will damage it and eventually cause
it to fail because of corrosion.
Be careful when performing electrical tests so as
to prevent accidental shorting of terminals. Such
mistakes can damage fuses or components. Also, a
second code could be set, making diagnosis of the
original problem more difficult.
4.3.2 ROAD TESTING A COMPLAINT
VEHICLE
Some complaints will require a test drive as part
of the repair verification procedure. The purpose of
the test drive is to try to duplicate the diagnostic
code or symptom condition.
CAUTION: Before road testing a vehicle, be
sure that all components are reassembled.
During the test drive, do not try to read the
DRBIIITscreen while in motion. Do not hang
the DRBIIITfrom the rear view mirror or
operate it yourself. Have an assistant
available to operate the DRBIIIT.
4.4 DIAGNOSIS
1. Your diagnostic test procedure must begin with a
thorough visual inspection of the system in ques-
tion for damaged components or disconnected
connectors. For ABS, the brake lamps must be
operational prior to continuing.
2. Connect the DRBIIItto the data link connector
located under the dash. If the DRBIIItdoes not
power up, check the power and ground supplies
to the connector.
3. Select the system in question. Turn the ignition
on. If the DRBIIItdisplays ``No Responseº, refer
to Communication in the Body Diagnostic Pro-
cedures manual to diagnose the symptom.
4. Read and record all diagnostic trouble codes. If
any additional codes are present, proceed to the
appropriate test.
5. For ABS, if there are no diagnostic trouble codes
present, select ``Inputs/Outputs'' and read the
Brake Switch and Brake Lamp Switch inputs as
you press and release the brake pedal. If the
6
GENERAL INFORMATION

display does not match the state of the pedal,
perform the proper test. For a problem with the
ªABSº warning indicator, refer to the proper test.
6. If no other problems are found, it will be neces-
sary to road test the vehicle.THE DRBIIIt
MUST NOT BE CONNECTED TO THE
DATA LINK CONNECTOR WHEN ROAD
TESTING FOR PROPER ANTILOCK OP-
ERATION. THE SYSTEM IS DISABLED
WHILE IN DIAGNOSTIC MODE.Perform
several antilock stops from above 50 Km/h (30
mph) and then repeat steps 2, 3, and 4. If any
diagnostic trouble codes are present, proceed to
the appropriate test.
7. The following conditions should be considered
``NORMAL'' operation, and no repairs should be
attempted to correct them.
± Brake pedal feedback during an ABS stop
(clicking, vibrating)
± Clicking, groaning or buzzing at 12 Km/h (8
mph) (drive off self test)
± Groaning noise during an ABS stop
± Slight brake pedal drop and pop noise when
ignition is initially turned on
± Brake pedal ratcheting down at the end of an
ABS stop
8. If the complaint is ABS ``cycling'' at the end of a
stop at low speeds, it may be caused by a
marginal wheel speed sensor signal. The sensor
air gap, tone wheel condition, and/or brakes
hanging up are possible causes of this condition.
9. After a road test in which no problems were
found, refer to any Technical Service Bulletins
that may apply.
5.0 REQUIRED TOOLS AND
EQUIPMENT
DRBIIIt(diagnostic read-out box)
jumper wires
ohmmeter
voltmeter
test light
oscilloscope
6.0 GLOSSARY OF TERMS
ABSantilock brake system
ACalternating current
BCMbody control module
BSbrake switch
BLSbrake lamp switch
CABcontroller antilock brakeDCdirect current
DLCdata link connector
DRBIIItdiagnostic read-out box
DTCdiagnostic test code
EBDelectronic brake distribution
ECMelectronic control module
HCUhydraulic control unit
HZHertz
ICinstrument cluster
LFleft front
LRleft rear
PMpump motor
RFright front
RRright rear
SOLsolenoid
TCStraction control system
TCSStraction control system switch
VSSvehicle speed signal
WSSwheel speed sensor
7
GENERAL INFORMATION

TEST ACTION APPLICABILITY
2 Turn the ignition off.
Disconnect the CAB harness connector.
Inspect the CAB/CAB harness connector for damage.
Is there any broken, bent, pushed out, corroded or spread terminals?All
Ye s!Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 3
3 Turn the ignition off.
Disconnect the CAB harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, check the Fused Optional Equipment
Relay Output circuit at the CAB harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Go To 4
No!Repair the Fused Optional Equipment Relay Output circuit for an
open.
Perform ABS VERIFICATION TEST - VER 1.
4 Turn the ignition off.
Disconnect the CAB harness connector.
Using a 12-volt test light connected to ground, check both Fused B(+) circuits at the
CAB harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Go To 5
No!Repair the Fused B(+) circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
5 Turn the ignition off.
Disconnect the CAB harness connector.
Using a 12-volt test light connected to 12-volts, check the CAB harness connector
Ground circuits.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Replace the Controller Antilock Brake in accordance with the
Service Information.
Perform ABS VERIFICATION TEST - VER 1.
No!Repair the Ground circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
11
BRAKES (CAB)
ANTI-LOCK BRAKE MODULE INTERNAL ÐContinued

TEST ACTION APPLICABILITY
6 Turn the ignition off.
Visually inspect the related wiring harness.
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out, or corroded terminals.
Were any problems found?All
Ye s!Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No!Test Complete.
12
BRAKES (CAB)
ANTI-LOCK BRAKE MODULE INTERNAL ÐContinued

TEST ACTION APPLICABILITY
2NOTE: This DTC will set if the Brake Switch, the Brake Lamp Switch, or
both switches are inoperative. It will be necessary to verify the functional-
ity of each switch.
NOTE: If the Brake Switch and the Brake Lamp Switch are inoperative, it
will be necessary to diagnose BOTH circuits.
Turn the ignition off.
Turn the ignition on.
With the DRBIIItin Inputs/Outputs, monitor the Brake Switch state while pressing
and releasing the brake pedal.
Does the DRBIIItdisplay change from CLOSED to OPEN as the brake pedal is
pressed and released?All
Ye s!Go To 3
No!Go To 4
3 Turn the ignition off.
Visually inspect the related wiring harness.
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out, or corroded terminals.
Were any problems found?All
Ye s!Repair as necessary.
Perform ABS VERIFICATION TEST - VER 1.
No!Test Complete.
4 Turn the ignition off.
Disconnect the C1 Brake Switch harness connector.
Turn the ignition on.
With the DRBIIItin Inputs/Outputs, monitor the Brake Switch state.
Connect a jumper wire between the Fused Ignition Switch Output circuit and Brake
Switch Output circuit in the C1 Brake Switch harness connector.
Does the DRBIIItdisplay a change from OPEN to CLOSED?All
Ye s!Replace the Brake Switch in accordance with the Service Infor-
mation.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 6
5 Turn the ignition off.
Disconnect the C2 Brake Lamp Switch harness connector.
Turn the ignition on.
With the DRBIIItin Inputs/Outputs, monitor the Brake Lamp Switch state.
Connect a jumper wire between the Fused Ignition Switch Output circuit and Brake
Lamp Switch Output circuit in the C2 Brake Lamp Switch harness connector.
Does the DRBIIItdisplay a change from OPEN to CLOSED?All
Ye s!Replace the Brake Lamp Switch in accordance with the Service
Information.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 6
18
BRAKES (CAB)
BRAKE SWITCH CIRCUIT ÐContinued

TEST ACTION APPLICABILITY
6 Turn the ignition off.
Disconnect the appropriate brake switch harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, check the Fused Ignition Switch
Output circuit at the harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Is the test light illuminated and bright?All
Ye s!Go To 7
No!Repair the Fused Ignition Switch Output circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
7 Turn the ignition off.
Disconnect the CAB harness connector.
Disconnect the appropriate brake switch harness connector.
Turn the ignition on.
Measure the voltage of the output circuit at the brake switch harness connector.
NOTE: Measurement is taken at the Brake Switch Output circuit or the
Brake Lamp Output circuit as determined by the previously performed
switch test.
Is there any voltage present?All
Ye s!Repair the affected circuit for a short to voltage.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 8
8 Turn the ignition off.
Disconnect the CAB harness connector.
Disconnect the appropriate brake switch harness connector.
Measure the resistance between ground and switch output circuit at the switch
connector.
NOTE: Measurement is taken at the Brake Switch Output circuit or the
Brake Lamp Output circuit as determined by the previously performed
switch test.
Is the resistance below 5.0 ohms?All
Ye s!Repair the affected circuit for a short to ground.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 9
9 Turn the ignition off.
Disconnect the CAB harness connector.
Disconnect the appropriate brake switch harness connector.
Measure the resistance of the output circuit between the switch harness connector
and the CAB harness connector.
NOTE: Measurement is taken at the Brake Switch Output circuit or the
Brake Lamp Output circuit as determined by the previously performed
switch test.
Is the resistance above 5.0 ohms?All
Ye s!Repair the affected circuit for an open.
Perform ABS VERIFICATION TEST - VER 1.
No!Go To 10
19
BRAKES (CAB)
BRAKE SWITCH CIRCUIT ÐContinued

TEST ACTION APPLICABILITY
10 Turn the ignition off.
Disconnect the CAB harness connector.
Disconnect the C1 Brake Switch and C2 Brake Lamp Switch harness connectors.
Measure the resistance between the Brake Switch Output circuit and Brake Lamp
Switch Output circuit in the C1 and C2 connectors.
Is the resistance below 5.0 ohms?All
Ye s!Repair the Brake Switch Output circuit for a short to the Brake
Lamp Switch Output circuit.
Perform ABS VERIFICATION TEST - VER 1.
No!Replace the Controller Antilock Brake in accordance with the
Service Information.
Perform ABS VERIFICATION TEST - VER 1.
20
BRAKES (CAB)
BRAKE SWITCH CIRCUIT ÐContinued