relay MERCEDES-BENZ SPRINTER 2006 Service Manual

TABLE OF CONTENTS - Continued
5.0 REQUIRED TOOLS AND EQUIPMENT.....................................13
6.0 GLOSSARY OF TERMS..................................................13
7.0 DIAGNOSTIC INFORMATION AND PROCEDURES...........................15
AIRBAG
AIRBAG WARNING INDICATOR - DRIVER HIGH.............................16
AIRBAG WARNING INDICATOR - DRIVER LOW..............................19
DRIVER SEAT BELT TENSIONER - INCORRECT FEEDBACK..................22
DRIVER SQUIB 1 - INCORRECT FEEDBACK................................22
INTERNAL 1...........................................................22
INTERNAL 2...........................................................22
INTERNAL 3...........................................................22
PASSENGER SEAT BELT TENSIONER - INCORRECT FEEDBACK..............22
PASSENGER SQUIB 1 - INCORRECT FEEDBACK............................22
STORED ENERGY FIRING 1..............................................22
STORED ENERGY FIRING 2..............................................22
DRIVER SEAT BELT TENSIONER CIRCUIT OPEN............................24
DRIVER SEAT BELT TENSIONER CIRCUIT SHORT..........................26
DRIVER SEAT BELT TENSIONER SHORT TO BATTERY.......................28
DRIVER SEAT BELT TENSIONER SHORT TO GROUND.......................31
DRIVER SQUIB 1 CIRCUIT OPEN.........................................33
DRIVER SQUIB 1 CIRCUIT SHORT........................................36
DRIVER SQUIB 1 SHORT TO BATTERY....................................39
DRIVER SQUIB 1 SHORT TO GROUND....................................42
LOSS OF IGNITION RUN - START.........................................45
PASSENGER SEAT BELT TENSIONER CIRCUIT OPEN.......................47
PASSENGER SEAT BELT TENSIONER CIRCUIT SHORT......................49
PASSENGER SEAT BELT TENSIONER SHORT TO BATTERY..................51
PASSENGER SEAT BELT TENSIONER SHORT TO GROUND..................54
PASSENGER SQUIB 1 CIRCUIT OPEN.....................................56
PASSENGER SQUIB 1 CIRCUIT SHORT....................................59
PASSENGER SQUIB 1 SHORT TO BATTERY................................62
PASSENGER SQUIB 1 SHORT TO GROUND................................65
*AIRBAG WARNING INDICATOR FLASHING.................................68
CABIN HEATER
A. HEATER PRE-TEST...................................................69
CIRC PUMP CONTROL OPEN............................................72
CIRC PUMP CONTROL SHORTED.........................................74
COMBUST FAN SHORTED...............................................76
COMBUST FAN SPEED INCORRECT......................................76
COMBUSTION FAN OPEN................................................76
CONTROL UNIT FAULTY.................................................77
DOSING PUMP OPEN...................................................78
DOSING PUMP SHORTED...............................................81
FAN STAGE 1 RELAY CONTROL OPEN....................................83
FAN STAGE 1 RELAY CONTROL SHORTED.................................85
FLAME DETECT PRIOR TO COMBUST.....................................87
FLAME OUT...........................................................88
NO START.............................................................88
FLAME SENSOR OPEN..................................................91
ii

TABLE OF CONTENTS - Continued
FLAME SENSOR SHORTED..............................................91
GLOW PIN OPEN.......................................................91
GLOW PIN SHORTED...................................................91
HEATER IN LOCKOUT MODE.............................................93
HEATER OVERHEATED..................................................93
SUCCESSIVE OVERHEATING............................................93
OVER VOLTAGE........................................................96
OVERHEATING SENSOR OPEN...........................................97
OVERHEATING SENSOR SHORTED.......................................97
TEMP SENSOR OPEN...................................................98
TEMP SENSOR SHORTED...............................................98
UNDER VOLTAGE......................................................99
COMMUNICATION
*NO RESPONSE FROM AIRBAG CONTROL MODULE.......................102
*NO RESPONSE FROM AUTOMATIC TEMPERATURE CONTROL..............104
*NO RESPONSE FROM CABIN HEATER MODULE..........................106
*NO RESPONSE FROM CENTRAL TIMER MODULE.........................108
*NO RESPONSE FROM CONTROLLER ANTILOCK BRAKE...................110
*NO RESPONSE FROM ENGINE CONTROL MODULE.......................112
*NO RESPONSE FROM HEATER BOOSTER MODULE.......................114
*NO RESPONSE FROM INSTRUMENT CLUSTER...........................116
*NO RESPONSE FROM RADIO..........................................118
*NO RESPONSE FROM SECURITY SYSTEM MODULE......................120
*NO RESPONSE FROM SENTRY KEY REMOTE ENTRY MODULE.............122
*NO RESPONSE FROM SHIFTER ASSEMBLY..............................124
*NO RESPONSE FROM TRANSMISSION CONTROL MODULE................126
HEATING & A/C
A/C COMPRESSOR CONTROL HIGH OR OPEN (ACTIVE)....................128
A/C COMPRESSOR CONTROL HIGH OR OPEN (STORED)...................130
A/C COMPRESSOR CONTROL SHORTED LOW (STORED)...................130
AIR OUTLET TEMP SENSOR HIGH OR OPEN (STORED)....................130
AIR OUTLET TEMP SENSOR SHORTED LOW (STORED)....................130
AUX FAN RELAY CONTROL HIGH OR OPEN (STORED).....................130
AUX FAN RELAY CONTROL SHORTED LOW (STORED).....................130
BLOWER STAGE 1 HIGH OR OPEN (STORED).............................130
BLOWER STAGE 1 SHORTED LOW (STORED).............................130
CABIN HEATER CONTROL HIGH OR OPEN (STORED)......................130
CABIN HEATER CONTROL SHORTED LOW (STORED)......................130
CIRC PUMP CONTROL HIGH OR OPEN (STORED).........................130
CIRC PUMP CONTROL SHORTED LOW (STORED).........................130
EVAP TEMP SENSOR HIGH OR OPEN (STORED)..........................130
EVAP TEMP SENSOR SHORTED LOW (STORED)..........................130
NO COMMUNICATION BUS (STORED)....................................130
NO COMMUNICATION WITH ECM (STORED)..............................130
NO COMMUNICATION WITH IC (STORED).................................130
RECIRC AIR SOLENOID CONTROL HIGH OR OPEN (STORED)...............130
RECIRC AIR SOLENOID CONTROL SHORTED LOW (STORED)...............130
REFRIG PRESS SENSOR HIGH OR OPEN (STORED).......................130
REFRIG PRESS SENSOR SHORTED LOW (STORED).......................130
WATER CYCLE VALVE CONTROL HIGH OR OPEN (STORED)................130
WATER CYCLE VALVE CONTROL SHORTED LOW (STORED)................130
iii

TABLE OF CONTENTS - Continued
A/C COMPRESSOR CONTROL SHORTED LOW (ACTIVE)....................132
AIR OUTLET TEMP SENSOR HIGH OR OPEN (ACTIVE).....................134
AIR OUTLET TEMP SENSOR SHORTED LOW (ACTIVE).....................136
ATC FUNCTION TEST COOL FAILURE....................................138
ATC FUNCTION TEST FAILURE..........................................138
ATC FUNCTION TEST HEAT FAILURE.....................................138
AUX FAN RELAY CONTROL HIGH OR OPEN (ACTIVE)......................140
AUX FAN RELAY CONTROL SHORTED LOW (ACTIVE)......................142
BLOWER STAGE 1 HIGH OR OPEN (ACTIVE)..............................144
BLOWER STAGE 1 SHORTED LOW (ACTIVE)..............................146
CABIN HEATER CONTROL HIGH OR OPEN (ACTIVE).......................148
CABIN HEATER CONTROL SHORTED LOW (ACTIVE).......................150
CIRC PUMP CONTROL HIGH OR OPEN (ACTIVE)..........................152
CIRC PUMP CONTROL SHORTED LOW (ACTIVE)..........................154
EVAP TEMP SENSOR HIGH OR OPEN (ACTIVE)...........................156
EVAP TEMP SENSOR SHORTED LOW (ACTIVE)...........................158
NO COMMUNICATION BUS (ACTIVE).....................................160
NO COMMUNICATION WITH ECM (ACTIVE)...............................163
NO COMMUNICATION WITH IC (ACTIVE)..................................165
RECIRC AIR SOLENOID CONTROL HIGH OR OPEN (ACTIVE)................167
RECIRC AIR SOLENOID CONTROL SHORTED LOW (ACTIVE)................169
REFRIG PRESS SENSOR HIGH OR OPEN (ACTIVE)........................171
REFRIG PRESS SENSOR SHORTED LOW (ACTIVE)........................173
WATER CYCLE VALVE CONTROL HIGH OR OPEN (ACTIVE).................175
WATER CYCLE VALVE CONTROL SHORTED LOW (ACTIVE).................177
INSTRUMENT CLUSTER
AMBIENT TEMP SENSOR OPEN/SHORT TO BATTERY......................179
AMBIENT TEMP SENSOR SHORT TO GROUND............................181
FUEL LEVEL SENSOR OPEN/SHORT TO BATTERY.........................182
FUEL LEVEL SENSOR SHORT TO GROUND...............................184
INSTRUMENT CLUSTER INTERNAL FAILURE B1043........................185
INSTRUMENT CLUSTER INTERNAL FAILURE B1053........................186
INSTRUMENT CLUSTER OVERVOLTAGE..................................187
NO CAN COMMUNICATION WITH ABS....................................188
NO CAN COMMUNICATION WITH ECM...................................190
NO CAN COMMUNICATION WITH TCM....................................192
PREGLOW INDICATOR LAMP FAILURE...................................194
SRS INDICATOR LAMP FAILURE.........................................195
POWER DOOR LOCKS/RKE
DRIVER DOOR AJAR INDICATOR DRIVER CIRCUIT SHORT TO GROUND......196
PASSENGER DOOR AJAR INDICATOR DRIVER CIRCUIT SHORT TO GROUND .198
REPLACE CONTROL MODULE..........................................200
RKE INTERFACE CIRCUIT SHORT TO GROUND - CTM......................201
RKE INTERFACE CIRCUIT SHORT TO GROUND - SKREEM..................203
RKE INTERFACE CIRCUIT SHORT TO VOLTAGE - CTM.....................205
RKE INTERFACE CIRCUIT SHORT TO VOLTAGE - SKREEM..................206
THE ACM HAS UNLOCKED THE DOORS..................................208
UNKNOWN TROUBLE CODE UNKNOWN DTC TYPE 2......................209
*RKE INOPERATIVE....................................................210
*RKE POOR RANGE...................................................211
iv

TABLE OF CONTENTS - Continued
VEHICLE THEFT/SECURITY
DRIVER CYLINDER LOCK SWITCH CIRCUIT SHORT TO GROUND............212
DRIVER CYLINDER UNLOCK SWITCH CIRCUIT SHORT TO GROUND.........214
FRONT DOOR JAMB SWITCH CIRCUIT SHORT TO GROUND................216
INTERNAL ERROR - SSM...............................................218
TOWING INCLINATION SENSOR BEYOND LIMITS..........................218
TOWING INCLINATION SENSOR VALUE IS INVALID.........................218
TOWING INCLINATION SENSOR VALUE IS MISSING........................218
INTRUSION SENSOR 1 CIRCUIT OPEN/SHORT TO GROUND................220
INTRUSION SENSOR 1 GROUND CIRCUIT OPEN..........................222
INTRUSION SENSOR 2 CIRCUIT OPEN/SHORT TO GROUND................223
INTRUSION SENSOR 2 GROUND CIRCUIT OPEN..........................225
INTRUSION SENSOR 3 CIRCUIT OPEN/SHORT TO GROUND................226
INTRUSION SENSOR 3 GROUND CIRCUIT OPEN..........................228
REAR OR SLIDING DOOR JAMB SWITCH CIRCUIT SHORT TO GROUND......229
RKE INTERFACE CIRCUIT FAILURE - SSM................................231
SECURITY SYSTEM INTERFACE FAILURE - SSM...........................233
SIREN CIRCUIT OPEN/SHORTED TO GROUND............................235
SIREN INTERNAL FAILURE.............................................237
SIREN SIGNAL CONTROL CIRCUIT SHORT TO GROUND....................238
WINDSHIELD WIPER & WASHER
CHECKING THE RAIN SENSOR/WIPER OPERATION........................239
VERIFICATION TESTS
VERIFICATION TESTS..................................................244
8.0 COMPONENT LOCATIONS..............................................249
8.1AIRBAG SYSTEM.................................................249
8.2AIRBAG CONTROL MODULE.......................................249
8.3DRIVER AIRBAG SQUIB...........................................249
8.4CLOCKSPRING..................................................250
8.5SEAT BELT TENSIONER...........................................250
8.6HEATING & A/C...................................................250
8.6.1AUTOMATIC TEMPERATURE CONTROL (ATC) SYSTEM
COMPONENTS...........................................250
8.6.2CABIN HEATER & HEATER BOOSTER SYSTEM COMPONENTS .251
8.6.3AUTO TEMP CONTROL, CABIN HEATER, & HEATER BOOSTER
FUSES & RELAYS........................................251
8.6.4EVAP TEMP SENSOR & AIR OUTLET TEMP SENSOR..........251
8.7INSTRUMENT CLUSTER...........................................252
8.7.1AMBIENT TEMPERATURE SENSOR.........................252
8.8POWER DOOR LOCKS/RKE........................................252
8.8.1CENTRAL TIMER MODULE.................................252
8.8.2SENTRY KEY REMOTE ENTRY MODULE.....................253
8.8.3DOOR LOCK MOTOR/AJAR SWITCH........................253
8.8.4CONTACT PLATES........................................253
8.8.5DOOR LOCK MOTOR/AJAR SWITCH CONNECTORS...........254
v

TABLE OF CONTENTS - Continued
FUSES (FUSE BLOCK NO. 2)............................................274
FUSES (FUSE BLOCK NO. 3)............................................276
FUSES (FUSE/RELAY BLOCK)...........................................278
HOOD AJAR SWITCH - BLACK...........................................278
HORN (VTSS).........................................................278
IGNITION LOCK SWITCH - BLACK........................................278
INSTRUMENT CLUSTER C1.............................................279
INSTRUMENT CLUSTER C2 - WHITE.....................................279
INTRUSION SENSOR NO. 1 - BLACK.....................................279
INTRUSION SENSOR NO. 2 - BLACK.....................................279
INTRUSION SENSOR NO. 3 - BLACK.....................................280
MASTER DOOR LOCK SWITCH..........................................280
PANIC ALARM SWITCH - BLACK.........................................280
FUSES (PDC).........................................................281
RADIO C1 - BLACK....................................................282
RADIO C2............................................................282
RECIRCULATED AIR SOLENOID VALVE...................................282
REFRIGERANT PRESSURE SENSOR.....................................282
A/C AUXILIARY FAN RELAY (RELAY BLOCK)...............................284
CIRCULATION PUMP RELAY-CABIN HEATER MODULE (RELAY BLOCK).......284
D+ RELAY NO. 2 (RELAY BLOCK)........................................284
FAN STAGE 1 RELAY (RELAY BLOCK)....................................284
OPTIONAL EQUIPMENT RELAY (RELAY BLOCK)...........................284
REMOTE KEYLESS ENTRY ANTENNA....................................284
SEAT BELT SWITCH...................................................284
SEAT BELT TENSIONER-DRIVER - YELLOW...............................285
SEAT BELT TENSIONER-PASSENGER - YELLOW...........................285
SECURITY SYSTEM MODULE C1 - BROWN...............................285
SECURITY SYSTEM MODULE C2 - LT. GREEN.............................286
SENTRY KEY REMOTE ENTRY MODULE (SKREEM)........................286
SHIFTER ASSEMBLY - BLACK...........................................286
SIREN - BLACK.......................................................286
STEERING ANGLE SENSOR............................................287
TOWING/INTRUSION SENSOR ON/OFF SWITCH...........................287
TRANSMISSION CONTROL MODULE C1 - BLACK..........................287
TRANSMISSION CONTROL MODULE C2 - BLACK..........................288
WATER CYCLE VALVE..................................................288
WINDOW DEFOGGER-LEFT REAR.......................................288
WINDOW DEFOGGER-RIGHT REAR......................................288
10.0 SCHEMATIC DIAGRAMS................................................289
10.1AIRBAG SYSTEM.................................................289
10.2COMMUNICATION................................................290
10.2.1COMMUNICATION K-LINES................................290
10.2.2CAN BUS NETWORK......................................291
10.3HEATING & A/C...................................................292
10.3.1AUTOMATIC TEMPERATURE CONTROL (ATC)................292
10.3.2CABIN HEATER MODULE (CHM)............................293
10.3.3HEATER BOOSTER MODULE (HBM).........................294
10.4INSTRUMENT CLUSTER...........................................295
vii

1.0 INTRODUCTION
The procedures contained in this manual include
all the specifications, instructions and graphics
needed to diagnose Sprinter body system problems.
The diagnostics in this manual are based on the
failure condition or symptom being present at the
time of diagnosis.
Please follow the recommendations below when
choosing your diagnostic path.
1. First make sure the DRBIIItis communicating
with the appropriate modules; i.e., if the
DRBIIItdisplays a ``No Response'' or a ``Bus6
Signals Open'' 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 identi-
fied, locate the matching test in the Table of
Contents and begin to diagnose the symptom.
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. All Charts and Graphs
are in Section 11.0.
An * placed before the symptom description indi-
cates a customer complaint without a DTC.
When repairs are required, refer to the appropri-
ate service information for the proper removal and
repair procedure.
Diagnostic procedures change every year. New
diagnostic systems may be added: carryover sys-
tems may be enhanced. READ THIS MANUAL
BEFORE TRYING TO DIAGNOSE A VEHICLE
DIAGNOSTIC TROUBLE CODE. It is recom-
mended that you review the entire manual to be-
come familiar with all the new and changed diag-
nostic procedures.
This book reflects many suggested changes from
readers of past issues. After using this book, if you
have any comments or suggestions, please fill out
the form in the back of this book and mail it back to
us.
1.1 SYSTEM COVERAGE
This diagnostic procedures manual covers all
Sprinter vehicles.
1.2 SIX-STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the body system 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 IDENTIFICATION OF
SYSTEM
The vehicle systems that are part of the ``body''
system are:
²Airbag
²Automatic Temperature Control
²Communication
²Instrument Cluster
²Power Door Locks/RKE
²Vehicle Theft Security System (VTSS)
²Wiper/Rain Sensor
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
The body system on the Sprinter consists of a
combination of modules that communicate with
each other using the CAN Bus (controller area
network). Through the CAN Bus, information about
the operation of vehicle components and circuits is
relayed quickly to the appropriate modules. Since
the CAN bus network is for intermodule communi-
cation only, the DRBIIItutilizes K-Lines to estab-
lish communications with each module. It is impor-
tant to note the CAN bus circuits are by no means
tied to the K-Lines. They are completely separate
from each other. For additional information on the
CAN bus and the K-Lines, refer to the Communi-
cation section of this general information.
3.1 AIRBAG SYSTEM
The Sprinter Airbag System contains the follow-
ing components:
²Airbag Control Module (ACM)
²Airbag Warning Indicator (SRS)
²Driver Airbags
²Clockspring
²Passenger Airbag
²Driver Seat Belt Tensioners
²Passenger Seat Belt Tensioners
The Airbag Control Module (ACM) has five major
functions: onboard diagnostics, determine the se-
verity of impacts, squib deployment and Accident
Response, K-Line communications. The ACM is
1
GENERAL INFORMATION

the A-pillar. The SKREEM receives radio messages
from the RKE transmitter (fob) and sends com-
mands via the RKE Interface circuit to the CTM. If
the vehicle is equipped with VTSS, the Security
System Module will be connected in series between
the SKREEM and the CTM.
Confirmation of the RKE Lock/Unlock state is
accomplished via the turn signals. When the vehicle
is locked via RKE the turn signals will flash three
times. When it is unlocked via RKE, the turn
signals will flash one time. If the vehicle has been
unlocked via RKE and no door is opened within 40
seconds, the entire vehicle will be locked again
automatically.
If a transmitter (fob) is operated more than 255
times in succession beyond the range of the receiver
(SKREEM), the RKE portion of the key will become
inoperative. In order to put it back in synchroniza-
tion it will be necessary to have ALL the other
transmitters that are used with this vehicle avail-
able and follow the following procedure:
1. Cycle the ignition on and off 2 times within 6
seconds (leave in off position).
2. Press the lock or unlock button of the disabled
transmitter within 3 seconds of turning the
ignition off.
3. Press any button (lock or unlock) 3 more times
within 6 seconds.
4. Wait 10 seconds.
5. Press any button of ALL other transmitters
belonging to this vehicle at least once within
the next 20 seconds.
For problems related to the Immobilizer function
of the SKREEM, see Service Information.
3.5.3 AUTO DOOR LOCKS
Whenever the engine is started, the CTM receives
a message to lock all doors except the drivers door.
This is accomplished through the D+ Relay. The D+
Relay is controlled by the Instrument Cluster which
receives a command from the ECM that the engine
is running. This relay supplies power to the CTM
(for auto locking), the daytime running lamps and
the rear window defogger.
3.5.4 ACCIDENT RESPONSE
The CTM is hardwired to the Airbag Control
Module through the Enhanced Accident Report
Driver circuit. Anytime the vehicle airbags are
deployed, the CTM will unlock all doors and a
9Crash9DTC will be stored in memory. The door
locks will be inoperative until that code is cleared. If
the vehicle is severly jarred, but not enough to
deploy the airbags, it is possible that the DTC could
be set and therefore the door locks would be inop-
erable. Whenever the door locks are not opera-tional, use the DRBIII and check DTC's . If the code
9ACM has unlocked the doors9appears, use the
DRBIII and erase it.
3.6 VEHICLE THEFT SECURITY SYSTEM
(VTSS)
The Security System Module (SSM) is located
under the driver's seat. The SSM communicates
with the DRBIII over the K-line. If equipped the
Vehicle Theft Security System will monitor the
following:
²door jamb switches
²hood ajar switch
²ignition switch
²interior of the vehicle for movement
²longitudinal and transverse movement of the
vehicle
²rear defogger grids for glass breakage
²trailer connector
To arm the system the hood and all of the doors
must be closed when the vehicle is locked with the
RKE transmitter or with the use of the key in the
driver door. If the key is used, it must be held in the
lock position for 2 seconds. When the system is first
activated, the hazard lamps will flash 3 times. Also
with the system armed, the Towing/Intrusion Sen-
sor On/Off Switch indicator will flash to indicate an
armed system. To disarm the system use the RKE
or the driver door lock cylinder. Unlocking and
opening one of the other doors with the system
armed will trip the vehicle theft security system.
Interior monitoring is done by the use of an
Intrusion Sensor located in the front headliner and
with one or two sensors in the ceiling of the cargo
area depending on how the vehicle is equipped.
Monitoring of the interior of the vehicle will begin
after the system has been armed for 30 seconds. The
on/off switch located on the instrument panel can be
used to turn off this feature with the ignition switch
in either the Locked/Off or ACC position. The vehi-
cle tow-monitoring feature can also be switched off
using this switch. Re-locking the vehicle a second
time will reactivate these features.
If a trailer is connected to the vehicle when the
system is armed, the SSM will sense a resistance
change on the turn signal circuits if the trailer
harness becomes disconnected and will trip the
alarm.
Tripping the vehicle theft security system will
cause the hazard lamps to flash and the siren to
sound at 30-second intervals. The siren is equipped
with it's own self-contained battery. In the event the
vehicle's battery power is disconnected the siren
will continue to sound on it's own.
10
GENERAL INFORMATION

Symptom:
CIRC PUMP CONTROL OPEN
POSSIBLE CAUSES
GROUND CIRCUIT OPEN
CIRCULATION PUMP RELAY HIGH SIDE CONTROL CIRCUIT OPEN
CIRCULATION PUMP RELAY
CABIN HEATER CONTROL UNIT
TEST ACTION APPLICABILITY
1WARNING: NEVER OPERATE THE HEATER IN AN ENCLOSED AREA
THAT DOES NOT HAVE EXHAUST VENTILATION FACILITIES. ALWAYS
VENT THE EXHAUST WHEN OPERATING THE HEATER. FAILURE TO
FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY
OR DEATH.
WARNING: ALLOW THE HEATER ASSEMBLY TO COOL BEFORE PER-
FORMING A COMPONENT INSPECTION/REPAIR/REPLACEMENT. FAIL-
URE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL
INJURY OR DEATH.
CAUTION: DO NOT PERFORM THIS TEST UNLESS DIRECTED HERE BY
THE HEATER PRE-TEST. ALWAYS PERFORM THE HEATER PRE-TEST
PRIOR TO PERFORMING ANY OTHER TEST FOR THE RESULT TO BE
VALID.
Turn the ignition off.
Remove the Circulation Pump Relay from the relay center.
Measure the resistance between ground and the Ground circuit (Circulation Pump
Relay connector terminal 85).
Is the resistance below 5.0 ohms?All
Ye s!Go To 2
No!Repair the Ground circuit for an open.
Perform HEATER VERIFICATION TEST - VER 1.
72
CABIN HEATER

TEST ACTION APPLICABILITY
2WARNING: NEVER OPERATE THE HEATER IN AN ENCLOSED AREA
THAT DOES NOT HAVE EXHAUST VENTILATION FACILITIES. ALWAYS
VENT THE EXHAUST WHEN OPERATING THE HEATER. FAILURE TO
FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY
OR DEATH.
WARNING: ALLOW THE HEATER ASSEMBLY TO COOL BEFORE PER-
FORMING A COMPONENT INSPECTION/REPAIR/REPLACEMENT. FAIL-
URE TO FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL
INJURY OR DEATH.
Turn the ignition off.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Cabin Heater harness connector.
Remove the Circulation Pump Relay from the relay center.
Measure the resistance of the Circulation Pump Relay High Side Control circuit
between the Cabin Heater harness connector and the relay center (Circulation Pump
Relay connector terminal 86).
Is the resistance below 5.0 ohms?All
Ye s!Go To 3
No!Repair the Circulation Pump Relay High Side Control circuit for
an open.
Perform HEATER VERIFICATION TEST - VER 1.
3WARNING: NEVER OPERATE THE HEATER IN AN ENCLOSED AREA
THAT DOES NOT HAVE EXHAUST VENTILATION FACILITIES. ALWAYS
VENT THE EXHAUST WHEN OPERATING THE HEATER. FAILURE TO
FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY
OR DEATH.
Turn the ignition off.
Reconnect the Cabin Heater harness connector.
Install a substitute relay in place of the Circulation Pump Relay.
Turn the ignition on.
Verify that the Cabin Heater is switched off.
Set the blend control to the max heat position and the mode control to the floor
position.
With the DRBIIIt, erase the Cabin Heater Module's DTCs.
Start the engine. Allow the engine to idle.
With the DRBIII, monitor for Cabin Heater Module DTCs while performing the
following step.
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.
Switch the Cabin Heater on. If necessary, allow the heater to run through at least one
cycle of operation (approximately 10 minutes), and then turn the heater off.
Turn the engine off.
Does the DRBIIItdisplay: CIRC PUMP CONTROL OPEN?All
Ye s!Replace the Cabin Heater Assembly in accordance with the
Service Information. Reinstall the original Circulation Pump
Relay.
Perform HEATER VERIFICATION TEST - VER 1.
No!Replace the original Circulation Pump Relay in accordance with
the Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
73
CABIN HEATER
CIRC PUMP CONTROL OPEN ÐContinued

Symptom:
CIRC PUMP CONTROL SHORTED
POSSIBLE CAUSES
CIRCULATION PUMP RELAY
CIRCULATION PUMP RELAY HIGH SIDE CONTROL CIRCUIT SHORTED TO GROUND
PUMP RELAY HIGH SIDE CONTROL CKT SHORTED TO PUMP RELAY GROUND CKT
CABIN HEATER CONTROL UNIT
TEST ACTION APPLICABILITY
1WARNING: NEVER OPERATE THE HEATER IN AN ENCLOSED AREA
THAT DOES NOT HAVE EXHAUST VENTILATION FACILITIES. ALWAYS
VENT THE EXHAUST WHEN OPERATING THE HEATER. FAILURE TO
FOLLOW THESE INSTRUCTIONS CAN RESULT IN PERSONAL INJURY
OR DEATH.
CAUTION: DO NOT PERFORM THIS TEST UNLESS DIRECTED HERE BY
THE HEATER PRE-TEST. ALWAYS PERFORM THE HEATER PRE-TEST
PRIOR TO PERFORMING ANY OTHER TEST FOR THE RESULT TO BE
VALID.
Turn the ignition off.
Install a substitute relay in place of the Circulation Pump Relay.
Turn the ignition on.
Verify that the Cabin Heater is switched off.
Set the blend control to the max heat position and the mode control to the floor
position.
With the DRBIIIt, erase the Cabin Heater Module's DTCs.
Start the engine. Allow the engine to idle.
With the DRBIII, monitor for Cabin Heater Module DTCs while performing the
following step.
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.
Switch the Cabin Heater on. If necessary, allow the heater to run through at least one
cycle of operation (approximately 10 minutes), and then switch the heater off.
Turn the engine off.
Does the DRBIIItdisplay: CIRC PUMP CONTROL SHORTED?All
Ye s!Go To 2
No!Replace the original Circulation Pump Relay in accordance with
the Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
74
CABIN HEATER