air condition MERCEDES-BENZ SPRINTER 2006 Owners Manual

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

BODY VERIFICATION TEST - VER 1 APPLICABILITY
1. Disconnect all jumper wires and reconnect all previously disconnected components and
connectors.
2. Ensure that all accessories are turned off and the battery is fully charged.
3. NOTE: Refer to the service information for proper programming procedures if the
ABM; ACM; ATC; CTM; ECM; IC; SKREEM; SLA; or SSM was replaced.
4. If the SKREEM was replaced, program all RKE transmitters used with this vehicle.
5. NOTE: Perform the next 8 steps of this procedure if either diagnosing the
Automatic Temperature Control (ATC) system or if repairs were made to the ATC
system. All of the following criteria must be met in order to successfully run the ATC
Function Test.
6. With DRBIIIt, record and erase ATC DTCs.
7. Place the shift lever in Park.
8. Start the engine. Allow the engine to reach normal operating temperature.
9. Set the blower to high speed.
10. Press the Air Conditioning switch On.
11. With the DRBIIIt, verify that the ambient temperature is above 59ÉF (15ÉC), the refrigerant
pressure is between 29 and 348 PSI (2 and 24 bar), the evaporator temperature is above 36.5ÉF
(2.5ÉC), and the coolant temperature is above 158ÉF (70ÉC).
12. With the DRBIIItin ATC, select System Tests and select ATC Function Test. When the ATC
Function Test is complete, proceed to the next step of this procedure.
13. With the DRBIIIt, read active ATC DTCs. If any DTC is active or if the original condition
is still present, proceed to the conclusion question and answer Yes.
14. With the DRBIIIt, record and erase all DTCs from ALL modules. Start and run the engine
for 2 minutes. Operate all functions of the system that caused the original concern.
15. Turn the ignition off and wait 5 seconds. Turn the ignition on and using the DRBIIIt, read
DTCs from ALL modules.
Are any DTC's present or is the original condition still present?All
Ye s!Repair is not complete, refer to the appropriate symptom.
No!Repair is complete.
245
VERIFICATION TESTS
Verification Tests ÐContinued

HEATER VERIFICATION TEST - VER 1 APPLICABILITY
1. WARNING: NEVER OPERATE THE HEATER IN AN ENCLOSED AREA THAT DOES
NOT HAVE EXHAUST VENTILATION FACILITIES. ALWAYS VENT THE HEATER's
EXHAUST WHEN OPERATING THE HEATER. FAILURE TO FOLLOW THESE IN-
STRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.
2. WARNING: ALLOW THE HEATER ASSEMBLY TO COOL BEFORE PERFORMING A
COMPONENT INSPECTION/REPAIR/REPLACEMENT. FAILURE TO FOLLOW
THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY OR DEATH.
3. NOTE: The heater's control unit will store up to five DTCs in its memory.
4. NOTE: If the heater's control unit detects a new fault in the system, one that is not
already stored in its memory, it will clear the oldest of the five stored DTCs, and it
will store the new fault's DTC.
5. NOTE: If the heater's control unit detects a reoccurrence of a stored fault, it will
overwrite that fault's DTC with the most recent occurrence.
6. Verify that the vehicle's battery is fully charged.
7. Verify that there is more than 1/8 of a tank of fuel in the vehicle's fuel tank. Add fuel, if
necessary.
8. Verify that all heater's coolant hoses and fuel lines are securely fastened to their respective
components.
9. Disconnect all jumper wires and reconnect all previously disconnected components and
connectors.
10. If a heater installation/cooling system service was performed, purge the coolant circuit of air
in accordance with the Service Information.
11. Turn the ignition on.
12. Verify that the Cabin Heater or Heater Booster is switched off.
13. Ensure that all accessories are turned off.
14. Set the blend control to the max heat position and the mode control to the floor position.
15. If a fuel system service requiring fuel to drain out of the heater's fuel line was performed,
prime the heater's Dosing Pump in accordance with the Service Information.
16. With the DRBIIIt, record and erase all DTCs from the Cabin Heater Module or Heater
Booster Module. Turn the ignition off, wait 5 seconds, then turn start the engine.
17. Allow the engine to idle.
18. NOTE: Do not disconnect the vehicle's battery or the heater's main power supply
while the heater is in operation or in run-down mode. Failure to follow these
instructions can result in excess emissions from the heater during heater operation.
19. Switch the Cabin Heater or Heater Booster on. Allow the heater to run through at least one
cycle of operation (approximately 10 minutes), and then turn the heater off.
20. With the DRBIIIt, read the Cabin Heater or Heater Booster Module's DTC.
21. Turn the engine off.
Are any DTC's present or is the original condition still present?All
Ye s!Repair is not complete, refer to the appropriate symptom.
No!Repair is complete.
246
VERIFICATION TESTS
Verification Tests ÐContinued

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

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

ver: 2.14
date: 26 Jul93
file: key_iff.cc
date: Jul 26 1993
line: 548
err: 0x1
User-Requested COLD Boot
Press MORE to switch between this display
and the application screen.
Press F4 when done noting information.
3.9.1 DRBIIITDOES NOT POWER UP
(BLANK SCREEN)
If the LED's do not light or no sound is emitted at
start up, check for loose cable connections or a bad
cable. Check the vehicle battery voltage (data link
16-way connector cavity 16). A minimum of 11 volts
is required to adequately power the DRBIIIt. Also
check for a good ground at DLC.
If all connections are proper between the
DRBIIItand the vehicle or other devices, and the
vehicle battery is fully charged, an inoperative
DRBIIItmay be the result or a faulty cable or
vehicle wiring.
3.9.2 DISPLAY IS NOT VISIBLE
Low temperatures will affect the visibility of the
display. Adjust the contrast to compensate for this
condition.
4.0 DISCLAIMERS, SAFETY,
WARNINGS
4.1 DISCLAIMERS
All information, illustrations, and specifications
contained in this manual are based on the latestinformation available at the time of publication.
The right is reserved to make changes at any time
without notice.
4.2 SAFETY
4.2.1 TECHNICIAN SAFETY INFORMATION
WARNING: ENGINES PRODUCE CARBON
MONOXIDE THAT IS ODORLESS, CAUSES
SLOWER REACTION TIME, AND CAN LEAD
TO SERIOUS INJURY. WHEN THE ENGINE IS
OPERATING, KEEP SERVICE AREAS WELL
VENTILATED OR ATTACH THE VEHICLE
EXHAUST SYSTEM TO THE SHOP EXHAUST
REMOVAL SYSTEM.
Set the parking brake and block the wheels before
testing or repairing the vehicle. It is especially
important to block the wheels on front-wheel drive
vehicles; the parking brake does not hold the front
drive wheels.
When servicing a vehicle, always wear eye pro-
tection, and remove any metal jewelry such as
watchbands or bracelets that might make an inad-
vertent electrical contact.
When diagnosing an antilock brake or adjustable
pedals system problem, it is important to follow
approved procedures where applicable. These pro-
cedures can be found in the service manual. Follow-
ing these procedures is very important to safety of
individuals performing diagnostic tests.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If it does not, false diagnostic codes
or error messages may occur.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the antilock brake and trac-
tion control are intended to be serviced in assembly
only. Attempting to remove or repair certain sub-
components may result in personal injury and/or
improper system operation. Only those components
with approved repair and installation procedures in
the service manual should be serviced.
5
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
4 Turn the ignition off.
Disconnect the Brake Pressure Sensor harness connector.
Disconnect the CAB harness connector.
Measure the resistance of the Brake Pressure Sensor signal circuit.
Measure the resistance of the Brake Pressure Sensor ground circuit.
Measure the resistance of the Brake Pressure Sensor 5 volt supply circuit.
Is the resistance above 5.0 ohms for any of the circuits?All
Ye s!Repair the Brake Pressure Sensor circuit(s) for an open
No!Go To 5
5 Turn the ignition off.
Disconnect the Brake Pressure Sensor harness connector.
Inspect the harness and connectors related to this circuit. If any problems are found,
repair as necessary.
If no problems are found, replace the Brake Pressure Sensor in accordance with the
Service Information.
With the DRBIIIt, clear DTCs.
Road test the vehicle and perform several braking maneuvers.
With the DRBIIIt, read DTCs.
Does this DTC reset?All
Ye s!Replace the CAB in accordance with the Service Information.
No!Test Complete.
6 The condition that set this DTC is not present at this time.
Monitor the DRBIIItwhile wiggle testing the related harness and connectors. Look
for any related parameters to change or for the DTC to reset.
Inspect the related harness and connectors.
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.
No!Test Complete.
16
BRAKES (CAB)
BRAKE PRESSURE SENSOR CIRCUIT ÐContinued

Symptom:
CAB CHECK SUM
When Monitored and Set Condition:
CAB CHECK SUM
When Monitored: Ignition On - Once
Set Condition: When the sum of all storage bytes are not equal to the original sum stored.
POSSIBLE CAUSES
INTERMITTENT CAB CHECK SUM DTC
DAMAGED CAB/CAB HARNESS CONNECTOR
FUSED OPTIONAL EQUIPMENT RELAY OUTPUT CIRCUIT OPEN
FUSED B(+) CIRCUIT OPEN
GROUND CIRCUIT OPEN
ANTI-LOCK BRAKE CONTROLLER
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, read DTCs.
With the DRBIIIt, erase DTCs.
Turn the ignition off.
Turn the ignition on.
With the DRBIIIt, read DTCs.
Does the DRBIIItdisplay CAB CHECK SUM?All
Ye s!Go To 2
No!Go To 6
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
21
BRAKES (CAB)