Mercedes-Benz Sprinter / Dodge Sprinter. Service manual — part 20
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
1
WARNING: 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 repair
All
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
Symptom:
DOSING PUMP OPEN
When Monitored and Set Condition:
DOSING PUMP OPEN
When Monitored:
With the ignition on.
Set Condition:
This DTC will set if the heater’s control unit detects abnormally high
voltage on the Dosing Pump control circuit.
POSSIBLE CAUSES
DOSING PUMP CONTROL CIRCUIT SHORTED HIGH
DOSING PUMP
DOSING PUMP CONTROL CIRCUIT OPEN
GROUND CIRCUIT OPEN
CABIN HEATER OR HEATER BOOSTER CONTROL UNIT
TEST
ACTION
APPLICABILITY
1
WARNING: 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 Cabin Heater or Heater Booster harness connector.
Turn the ignition on.
Measure the voltage between the Dosing Pump Control circuit and ground.
Is the voltage above 0.2 volts?
All
Yes
→ Repair the Dosing Pump Control circuit for a short to voltage.
Perform HEATER VERIFICATION TEST - VER 1.
No
→ Go To 2
78
CABIN HEATER
TEST
ACTION
APPLICABILITY
2
WARNING: 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 DRBIII
t in 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
Yes
→ Replace the Dosing Pump in accordance with the Service Infor-
mation.
Perform HEATER VERIFICATION TEST - VER 1.
No
→ Go To 3
3
WARNING: 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
Yes
→ 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 —
Continued
TEST
ACTION
APPLICABILITY
4
WARNING: 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
Yes
→ 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 —
Continued
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