2006 MERCEDES-BENZ SPRINTER heater

Symptom:
*NO RESPONSE FROM HEATER BOOSTER MODULE
POSSIBLE CAUSES
CHECK POWERS AND GROUNDS TO THE HEATER BOOSTER MODULE
MODULE - INTERNAL SHORT TO GROUND
K-IC, ATC, HBM, CHM CIRCUIT SHORTED TO GROUND
MODULE - INTERNAL SHORT TO VOLTAGE
K-IC, ATC, HBM, CHM CIRCUIT SHORTED TO VOLTAGE
K-IC, ATC, HBM, CHM CIRCUIT OPEN
HEATER BOOSTER MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Disconnect the Heater Booster Module harness connector.
Check each power and ground circuit to the module.
Were any problems found?All
Ye s!Refer to the wiring diagrams located in the service information to
help isolate an open or shorted condition. Repair as necessary.
Perform BODY VERIFICATION TEST - VER 1.
No!Go To 2
2 Turn the ignition off.
Disconnect the Heater Booster Module harness connector.
Disconnect the DRBIIItfrom the DLC.
Measure the resistance between ground and the K-IC, ATC, HBM, CHM circuit.
Is the resistance below 5.0 ohms?All
Ye s!Go To 3
No!Go To 4
3 Turn the ignition off.
Disconnect the Heater Booster Module harness connector.
Measure the resistance between ground and the K-IC, ATC, HBM, CHM circuit.
While monitoring the ohmmeter, disconnect each module (IC, ATC, CHM) one at a
time.
NOTE: The vehicle may not be equipped with all the above modules.
Is the resistance below 5.0 ohms with all the above modules disconnected?All
Ye s!Repair the K-IC, ATC, HBM, CHM circuit for a short to ground.
Perform BODY VERIFICATION TEST - VER 1.
No!Replace the Module, that when disconnected the short was
eliminated, in accordance with the service information.
Perform BODY VERIFICATION TEST - VER 1.
11 4
COMMUNICATION

TEST ACTION APPLICABILITY
4 Turn the ignition off.
Disconnect the DRBIIItfrom the DLC.
Disconnect the Heater Booster Module harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the K-IC, ATC, HBM, CHM
circuit.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Go To 5
No!Go To 6
5 Turn the ignition off.
Disconnect the Heater Booster Module harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the K-IC, ATC, HBM, CHM
circuit.
While monitoring the test light, disconnect each module (IC, ATC, CHM) one at a
time.
NOTE: The vehicle may not be equipped with all the above modules.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly with all the above modules disconnected?All
Ye s!Repair the K-IC, ATC, HBM, CHM circuit for a short to voltage.
Perform BODY VERIFICATION TEST - VER 1.
No!Replace the Module, that when disconnected the short was
eliminated, in accordance with the service information.
Perform BODY VERIFICATION TEST - VER 1.
6 Turn the ignition off.
Disconnect the Heater Booster Module harness connector.
Disconnect the DRBIIItfrom the DLC.
Measure the resistance of the K-IC, ATC, HBM, CHM circuit between the HBM
connector and the DLC.
Is the resistance below 5.0 ohms?All
Ye s!Replace the Heater Booster Module in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No!Repair the K-IC, ATC, HBM, CHM circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
11 5
COMMUNICATION
*NO RESPONSE FROM HEATER BOOSTER MODULE ÐContinued

Symptom List:
A/C COMPRESSOR CONTROL HIGH OR OPEN (STORED)
A/C COMPRESSOR CONTROL SHORTED LOW (STORED)
AIR OUTLET TEMP SENSOR HIGH OR OPEN (STORED)
AIR OUTLET TEMP SENSOR SHORTED LOW (STORED)
AUX FAN RELAY CONTROL HIGH OR OPEN (STORED)
AUX FAN RELAY CONTROL SHORTED LOW (STORED)
BLOWER STAGE 1 HIGH OR OPEN (STORED)
BLOWER STAGE 1 SHORTED LOW (STORED)
CABIN HEATER CONTROL HIGH OR OPEN (STORED)
CABIN HEATER CONTROL SHORTED LOW (STORED)
CIRC PUMP CONTROL HIGH OR OPEN (STORED)
CIRC PUMP CONTROL SHORTED LOW (STORED)
EVAP TEMP SENSOR HIGH OR OPEN (STORED)
EVAP TEMP SENSOR SHORTED LOW (STORED)
NO COMMUNICATION BUS (STORED)
NO COMMUNICATION WITH ECM (STORED)
NO COMMUNICATION WITH IC (STORED)
RECIRC AIR SOLENOID CONTROL HIGH OR OPEN (STORED)
RECIRC AIR SOLENOID CONTROL SHORTED LOW (STORED)
REFRIG PRESS SENSOR HIGH OR OPEN (STORED)
REFRIG PRESS SENSOR SHORTED LOW (STORED)
WATER CYCLE VALVE CONTROL HIGH OR OPEN (STORED)
WATER CYCLE VALVE CONTROL SHORTED LOW (STORED)
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be A/C COMPRESSOR CONTROL
HIGH OR OPEN (STORED).
When Monitored and Set Condition:
NO COMMUNICATION BUS (STORED)
When Monitored: With the ignition on.
Set Condition: This DTC will set if the Automatic Temperature Control (ATC) fails to
receive all module messages.
NO COMMUNICATION WITH ECM (STORED)
When Monitored: With the ignition on.
Set Condition: This DTC will set if the Automatic Temperature Control (ATC) fails to
receive all messages from the ECM.
130
HEATING & A/C

Symptom:
CABIN HEATER CONTROL HIGH OR OPEN (ACTIVE)
POSSIBLE CAUSES
CABIN HEATER OR HEATER BOOSTER CONTROL UNIT
CABIN HEATER CONTROL CIRCUIT SHORTED TO VOLTAGE
AUTOMATIC TEMPERATURE CONTROL (ATC)
CABIN HEATER CONTROL CIRCUIT OPEN
AUTOMATIC TEMPERATURE CONTROL (ATC)
TEST ACTION APPLICABILITY
1 Turn the ignition on.
Verify that the Cabin Heater or Heater Booster is switched off.
Turn the ignition off.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Cabin Heater or Heater Booster harness connector.
Connect a 12-volt test light between the Cabin Heater Control circuit and ground.
Turn the ignition on. The test light should operate as follows:
With the Cabin Heater or Heater Booster switched off, the test light should not
illuminate.
Press the Cabin Heater or Heater Booster switch on. The test light should illuminate
brightly.
Does the test light function as specified?All
Yes, Light Only Illuminates w/Switch On
Replace the Cabin Heater Assembly or the Heater Booster Assem-
bly in accordance with the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No, Light Illuminates w/Switch Off
Go To 2
No, Light Will Not Illuminate
Go To 3
2 Turn the ignition off.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Cabin Heater or Heater Booster harness connector.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Turn the ignition on.
Measure the voltage of the Cabin Heater Control circuit.
Is the voltage above 0.2 volts?All
Ye s!Repair the Cabin Heater Control circuit for a short to voltage.
Perform BODY VERIFICATION TEST - VER 1.
No!Replace the Automatic Temperature Control (ATC) in accordance
with the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
148
HEATING & A/C

TEST ACTION APPLICABILITY
3 Turn the ignition off.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Disconnect the Cabin Heater or Heater Booster harness connector.
Measure the resistance of the Cabin Heater Control circuit between the Automatic
Temperature Control (ATC) C1 harness connector and the Cabin Heater or Heater
Booster harness connector (as applicable).
Is the resistance below 5.0 ohms?All
Ye s!Replace the Automatic Temperature Control (ATC) in accordance
with the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No!Repair the Cabin Heater Control circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
149
HEATING & A/C
CABIN HEATER CONTROL HIGH OR OPEN (ACTIVE) ÐContinued

Symptom:
CABIN HEATER CONTROL SHORTED LOW (ACTIVE)
POSSIBLE CAUSES
CABIN HEATER OR HEATER BOOSTER CONTROL UNIT
CABIN HEATER CONTROL CIRCUIT SHORTED TO GROUND
CABIN HEATER CONTROL CIRCUIT SHORTED TO GROUND CIRCUIT
CABIN HEATER CONTROL CIRCUIT SHORTED TO SENSOR GROUND CIRCUIT
AUTOMATIC TEMPERATURE CONTROL (ATC)
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Disconnect the Cabin Heater or Heater Booster harness connector.
NOTE: All of the following criteria must be met in order to successfully run
the ATC Function Test.
Place the shift lever in Park.
Turn the ignition on.
With the DRBIIIt, record and erase ATC DTC's.
Start the engine. Allow the engine to reach normal operating temperature.
Set the blower to high speed.
Press the Air Conditioning switch On.
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).
With the DRBIIItin Automatic Temperature Control (ATC), select System Tests and
select ATC Function Test. When the ATC Function Test is complete, proceed as
follows:
With the DRBIIIt, read the active ATC DTCs.
Does the DRBIIItdisplay: CABIN HEATER CONTROL SHORTED LOW?All
Ye s!Go To 2
No!Replace the Cabin Heater Assembly or the Heater Booster assem-
bly in accordance with the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
2 Turn the ignition off.
Disconnect the Cabin Heater or Heater Booster harness connector.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Measure the resistance between ground and the Cabin Heater Control circuit.
Is the resistance below 30k ohms?All
Ye s!Repair the Cabin Heater Control circuit for a short to ground.
Perform BODY VERIFICATION TEST - VER 1.
No!Go To 3
150
HEATING & A/C

TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect the Cabin Heater or Heater Booster harness connector.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Measure the resistance between the Cabin Heater Control circuit and the Ground
circuit in the Automatic Temperature Control (ATC) C1 harness connector.
Is the resistance below 30k ohms?All
Ye s!Repair the Cabin Heater Control circuit for a short to the Ground
circuit.
Perform BODY VERIFICATION TEST - VER 1.
No!Go To 4
4 Turn the ignition off.
Disconnect the Cabin Heater or Heater Booster harness connector.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Measure the resistance between the Cabin Heater Control circuit and the Sensor
Ground circuit in the Automatic Temperature Control (ATC) C1 harness connector.
Is the resistance below 30k ohms?All
Ye s!Repair the Cabin Heater Control circuit for a short to the Sensor
Ground circuit.
Perform BODY VERIFICATION TEST - VER 1.
No!Replace the Automatic Temperature Control (ATC) in accordance
with the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
151
HEATING & A/C
CABIN HEATER CONTROL SHORTED LOW (ACTIVE) 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