2006 MERCEDES-BENZ SPRINTER warning

Symptom:
A. HEATER PRE-TEST
POSSIBLE CAUSES
NO RESPONSE FROM CABIN HEATER MODULE OR HEATER BOOSTER MODULE
CABIN HEATER MODULE OR HEATER BOOSTER MODULE DTC(S) PRESENT
AUTOMATIC TEMPERATURE CONTROL DTC(S) PRESENT
HEATER SYSTEM COMPONENTS
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.
Turn the ignition off and either allow the engine coolant to cool down to at least 50ÉC
(122ÉF) or cold soak the engine.
CAUTION: When using a powered exhaust ventilation system, do not attach
the exhaust ventilation hose directly to the heater's exhaust pipe. Too much
suction can prevent heater operation.
When using a powered exhaust ventilation system, affix the ventilation hose to the
heater's exhaust pipe or to the vehicle in such a manor that the end of the ventilation
hose remains approximately three inches away from the end of the exhaust pipe.
When using a non-powered exhaust ventilation system, affix the ventilation hose
directly to the heater's exhaust pipe.
Turn the ignition on.
With the DRBIIIt, attempt to communicate with the Cabin Heater Module or Heater
Booster Module and the Automatic Temperature Control Module.
Does the DRBIIItdisplay: NO RESPONSE?All
Ye s!Refer to the Communication Category for the related symptom.
Perform HEATER VERIFICATION TEST - VER 1.
No!Go To 2
69
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.
NOTE: The heater's control unit will store up to five DTCs in its memory.
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.
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.
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, record and erase the Cabin Heater or Heater Booster Module's
DTCs.
Start the engine. Allow the engine to idle.
With the DRBIIIt, monitor for Cabin Heater Module 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 operable, allow the heater to run
through at least one cycle of operation (approximately 10 minutes), and then switch
the heater off.
Does the DRBIIItdisplay any DTCs?All
Ye s!If the Heater In Lockout Mode DTC is present, record and erase
DTCs before performing any diagnostic procedures. Return to the
symptom list and choose the symptom(s).
Perform HEATER VERIFICATION TEST - VER 1.
No!Go To 3
70
CABIN HEATER
A. HEATER PRE-TEST ÐContinued

TEST ACTION APPLICABILITY
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 on.
With the DRBIIIt, read Automatic Temperature Control DTCs.
Are any DTCs present?All
Ye s!Refer to Heating & A/C information for the related symptom(s).
Perform HEATER VERIFICATION TEST - VER 1.
No!Allow heater assembly to cool. Inspect the fuel line, air intake and
exhaust, and coolant hoses for restrictions, obstructions, loose
clamps, leakage, etc. Repair as necessary. Check the harness
connectors and grounds. Clean and repair as necessary.
Perform HEATER VERIFICATION TEST - VER 1.
71
CABIN HEATER
A. HEATER PRE-TEST ÐContinued

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

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 Circulation Pump Relay from the relay center.
Measure the resistance between ground and the Circulation Pump Relay High Side
Control circuit.
Is the resistance below 10K ohms?All
Ye s!Repair the Circulation Pump Relay High Side Control circuit for
a short to ground. Reinstall the original Circulation Pump 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 Circulation Pump Relay from the relay center.
Measure the resistance between the Circulation Pump Relay High Side Control
circuit and the Ground circuit (Circulation Pump Relay connector terminal 86 and
85).
Is the resistance below 10K ohms?All
Ye s!Repair the Circulation Pump 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.
75
CABIN HEATER
CIRC PUMP CONTROL SHORTED ÐContinued

Symptom List:
COMBUST FAN SHORTED
COMBUST FAN SPEED INCORRECT
COMBUSTION FAN OPEN
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be COMBUST FAN SHORTED.
POSSIBLE CAUSES
COMBUSTION AIR FAN
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.
76
CABIN HEATER