service MERCEDES-BENZ SPRINTER 2006 Workshop Manual

Symptom:
CONTROL UNIT FAULTY
When Monitored and Set Condition:
CONTROL UNIT FAULTY
When Monitored: During heater activation and operation.
Set Condition: This DTC will set if the heater's control unit detects an internal failure in
its microprocessor/memory.
POSSIBLE CAUSES
CABIN HEATER OR HEATER BOOSTER 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.
View repairAll
Repair
Replace the Cabin Heater Assembly or Heater Booster Assembly
in accordance with the Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
77
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.
Reconnect the Cabin Heater or Heater Booster harness connector.
Disconnect the Dosing Pump harness connector.
Connect a 12-volt test light between the Dosing Pump Control circuit and the Ground
circuit in the Dosing Pump harness connector.
Turn the ignition on.
With the DRBIIItin System Tests, select Dosing Pump Output. The test Light
should illuminate brightly and flash continuously during actuation.
Does the test light operate as specified?All
Ye s!Replace the Dosing Pump in accordance with the Service Infor-
mation.
Perform HEATER VERIFICATION TEST - VER 1.
No!Go To 3
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.
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 or Heater Booster harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Dosing Pump harness connector.
Measure the resistance of the Dosing Pump Control circuit between the Dosing Pump
harness connector and the Cabin Heater or Heater Booster harness connector (as
applicable).
Is the resistance below 5.0 ohms?All
Ye s!Go To 4
No!Repair the Dosing Pump Control circuit for an open.
Perform HEATER VERIFICATION TEST - VER 1.
79
CABIN HEATER
DOSING PUMP OPEN ÐContinued

TEST ACTION APPLICABILITY
4WARNING: 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 or Heater Booster harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Dosing Pump harness connector.
Measure the resistance of the Ground circuit between the Dosing Pump harness
connector and the Cabin Heater or Heater Booster harness connector.
Is the resistance below 5.0 ohms?All
Ye s!Replace the Cabin Heater Assembly or Heater Booster Assembly
in accordance with the Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
No!Repair the Ground circuit for an open.
Perform HEATER VERIFICATION TEST - VER 1.
80
CABIN HEATER
DOSING PUMP OPEN ÐContinued

Symptom:
DOSING PUMP SHORTED
POSSIBLE CAUSES
DOSING PUMP SHORTED TO GROUND
DOSING PUMP CONTROL CIRCUIT SHORTED TO GROUND CIRCUIT
DOSING PUMP CONTROL CIRCUIT SHORTED TO GROUND
CABIN HEATER OR HEATER BOOSTER 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.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Dosing Pump harness connector.
Turn the ignition on.
Verify that the Cabin Heater or Heater Booster 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 or Heater Booster Module's DTCs.
Start the engine. Allow the engine to idle.
With the DRBIII, monitor for Cabin Heater or Heater Booster 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 or Heater Booster 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: DOSING PUMP HIGH OR OPEN?All
Ye s!Replace the Dosing Pump in accordance with the Service Infor-
mation.
Perform HEATER VERIFICATION TEST - VER 1.
No!Go To 2
81
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.
Disconnect the battery in accordance with the Service information.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Cabin Heater or Heater Booster harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Dosing Pump harness connector.
Measure the resistance between the Dosing Pump Control circuit and the Ground
circuit in the Dosing Pump harness connector.
Is the resistance below 10K ohms?All
Ye s!Repair the Dosing Pump Control circuit for a short to the Ground
circuit.
Perform HEATER VERIFICATION TEST - VER 1.
No!Go To 3
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.
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.
Disconnect the battery in accordance with the Service information.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Cabin Heater or Heater Booster harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Dosing Pump harness connector.
Measure the resistance between ground and the Dosing Pump Control circuit.
Is the resistance below 10K ohms?All
Ye s!Repair the Dosing Pump Control circuit for a short to ground.
Perform HEATER VERIFICATION TEST - VER 1.
No!Replace the Cabin Heater Assembly or Heater Booster Assembly
in accordance with the Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
82
CABIN HEATER
DOSING PUMP SHORTED ÐContinued

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 Fan Stage 1 Relay from the relay center.
Measure the resistance of the Fan Stage 1 Relay High Side Control circuit between
the Cabin Heater harness connector and the relay center (Fan Stage 1 Relay
connector terminal 86).
Is the resistance below 5.0 ohms?All
Ye s!Go To 3
No!Repair the Fan Stage 1 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 Fan Stage 1 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: FAN STAGE 1 RELAY CONTROL OPEN?All
Ye s!Replace the Cabin Heater Assembly in accordance with the
Service Information. Reinstall the original Fan Stage 1 Relay.
Perform HEATER VERIFICATION TEST - VER 1.
No!Replace the original Fan Stage 1 Relay in accordance with the
Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
84
CABIN HEATER
FAN STAGE 1 RELAY CONTROL OPEN ÐContinued

Symptom:
FAN STAGE 1 RELAY CONTROL SHORTED
POSSIBLE CAUSES
FAN STAGE 1 RELAY
FAN STAGE 1 RELAY HIGH SIDE CONTROL CIRCUIT SHORTED TO GROUND
FAN STAGE 1 RELAY HIGH SIDE CONTROL CIRCUIT SHORTED TO GROUND CIRCUIT
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 Fan Stage 1 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: FAN STAGE 1 RELAY CONTROL SHORTED?All
Ye s!Go To 2
No!Replace the original Fan Stage 1 Relay in accordance with the
Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
85
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 substitute Fan Stage 1 Relay from the relay center.
Measure the resistance between ground and the Fan Stage 1 Relay High Side Control
circuit.
Is the resistance below 10K ohms?All
Ye s!Repair the Fan Stage 1 Relay High Side Control circuit for a short
to ground. Reinstall the original Fan Stage 1 Relay.
Perform HEATER VERIFICATION TEST - VER 1.
No!Go To 3
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.
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 Fan Stage 1 Relay from the relay center.
Measure the resistance between the Fan Stage 1 Relay High Side Control circuit and
the Ground circuit (Fan Stage 1 Relay connector terminal 86 and 85).
Is the resistance below 10K ohms?All
Ye s!Repair the Fan Stage 1 Relay High Side Control circuit for a short
to the Ground circuit.
Perform HEATER VERIFICATION TEST - VER 1.
No!Replace the Cabin Heater Assembly in accordance with the
Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
86
CABIN HEATER
FAN STAGE 1 RELAY CONTROL SHORTED ÐContinued

Symptom:
FLAME DETECT PRIOR TO COMBUST
When Monitored and Set Condition:
FLAME DETECT PRIOR TO COMBUST
When Monitored: During heater start up.
Set Condition: This DTC will set if the Flame Sensor's resistance is not within the
expected parameters.
POSSIBLE CAUSES
HEATER'S AIR INTAKE/EXHAUST RESTRICTED
FLAME SENSOR
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.
Inspect the heater's air intake pipe and exhaust pipe for restrictions and obstruc-
tions.
Is the heater's air intake pipe and exhaust pipe Ok?All
Ye s!Replace the Cabin Heater Assembly or Heater Booster Assembly
in accordance with the Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
No!Repair the heater's air intake/exhaust as necessary in accordance
with the Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
87
CABIN HEATER

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: ALWAYS SWITCH THE HEATER OFF PRIOR TO REFUELING
THE VEHICLE. FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RE-
SULT 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.
Verify that there is more than an 1/8 of a tank of fuel in the vehicle's fuel tank.
Is there more than an 1/8 of a tank of fuel in the vehicle's fuel tank?All
Ye s!Go To 2
No!Add fuel to the vehicle's fuel tank to bring the fuel level above 1/8
of a tank.
Perform HEATER VERIFICATION TEST - VER 1.
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.
Inspect the heater's fuel line exterior for restrictions, leakage, and damage.
Verify that the heater's fuel line is installed correctly.
NOTE: Waxed fuel can obstruct the fuel line and reduce flow. Check for the
appropriate winter grade fuel and replace as necessary.
Check for obstructions in the heater's fuel line. Refer to Fuel Line, Cleaning in the
Service Information.
Is the heater's fuel line Ok?All
Ye s!Go To 3
No!Repair the heater's fuel line as necessary in accordance with the
Service Information.
Perform HEATER VERIFICATION TEST - VER 1.
89
CABIN HEATER
FLAME OUT ÐContinued