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Symptom:
RECIRC DOOR TRAVEL TOO LARGE (ACTIVE)
When Monitored and Set Condition:
RECIRC DOOR TRAVEL TOO LARGE (ACTIVE)
When Monitored: Ignition in RUN and IOD fuse installed.
Set Condition: This DTC is set when the ATC monitors the travel range during system
initialization and the measured range is greater than expected.
POSSIBLE CAUSES
CHECK THE ATC FOR DTCS
RECIRCULATION DOOR ACTUATOR
RECIRCULATION DOOR LINKAGE
AT C
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, read the active ATC DTCs.
Is the RECIRC DOOR NOT RESPONDING DTC set?All
Ye s®Return to the symptom list and choose the symptom.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 2
2 Turn the ignition off.
Remove the Recirculation Door Actuator.
By hand, attempt to rotate the Recirculation Door Actuator in both directions.
Did the Recirculation Door Actuator turn in either direction?All
Ye s®Replace the Recirculation Door Actuator.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 3
292
AUTOMATIC TEMPERATURE CONTROL
Page 322 of 4284
TEST ACTION APPLICABILITY
3 Remove the Recirculation Door Actuator. Rotate the recirculation door (door only).
Note: This should rotate approximately 45 degrees from stop to stop.
Inspect the recirculation door linkage for excessive wear or missing linkage.
Were any mechanical problems found?All
Ye s®Repair or replace the recirculation door/linkage as necessary.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
No®Replace the ATC.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
293
AUTOMATIC TEMPERATURE CONTROL
RECIRC DOOR TRAVEL TOO LARGE (ACTIVE) ÐContinued
Page 323 of 4284

Symptom:
RECIRC DOOR TRAVEL TOO SMALL (ACTIVE)
When Monitored and Set Condition:
RECIRC DOOR TRAVEL TOO SMALL (ACTIVE)
When Monitored: Ignition in RUN and IOD fuse installed.
Set Condition: This DTC is set when the ATC monitors the travel range during system
initialization and the measured range is less than expected.
POSSIBLE CAUSES
CHECK THE ATC FOR DTCS
AT C
OBSTRUCTED RECIRC DOOR
RECIRCULATION DOOR ACTUATOR
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, read the active ATC DTCs.
Is the RECIRC DOOR NOT RESPONDING DTC set?All
Ye s®Return to the symptom list and choose the symptom.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 2
2 Turn the ignition off.
Disconnect the Recirculation Door Actuator harness connector.
Connect a 12-volt Test Light between the Recirculation Door Driver (A) and (B)
circuits.
Turn the ignition on.
While monitoring the test light, press the recirculation control button from off to on.
Note: Observe test light for approximately 30 seconds.
Does the test light start to flash and stay flashing?All
Ye s®Go To 3
No®Replace the ATC.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
294
AUTOMATIC TEMPERATURE CONTROL
Page 324 of 4284
TEST ACTION APPLICABILITY
3 Remove the Recirculation Door Actuator. Rotate the recirculation door (door only).
Note: This should rotate approximately 45 degrees from stop to stop.
Does the recirculation door move smoothly in both directions?All
Ye s®Replace the Recirculation Door Actuator.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
No®Repair or replace the recirculation door as necessary.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
295
AUTOMATIC TEMPERATURE CONTROL
RECIRC DOOR TRAVEL TOO SMALL (ACTIVE) ÐContinued
Page 325 of 4284

Symptom List:
CABIN HEATER PRE-TEST
CABIN HEATER CONTROL CIRCUIT OPEN (STORED)
CABIN HEATER CONTROL CIRCUIT SHORT TO BATTERY
(STORED)
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be A. CABIN HEATER PRE-TEST.
When Monitored and Set Condition:
CABIN HEATER CONTROL CIRCUIT OPEN (STORED)
When Monitored: When the DCHA system is off.
Set Condition: The DCHA Low Side Driver inside the FCM expects to see a system
voltage of 13.8 volts through the DCHA relay coil when the DCHA system is off. This DTC
will set if the FCM sees a voltage below 3.5 volts on the Cabin Heater Assist Control circuit
during this time.
CABIN HEATER CONTROL CIRCUIT SHORT TO BATTERY (STORED)
When Monitored: During DCHA activation and operation.
Set Condition: This DTC will set if the FCM sees between 5.0 and 15.0 volts on the Cabin
Heater Assist Control circuit.
POSSIBLE CAUSES
NO RESPONSE FROM CABIN HEATER MODULE
DTC(S) PRESENT
CABIN HEATER INOPERABLE FROM A/C - HEATER MODULE
STORED DCHA DTC(S) TEST COMPLETE
TEST ACTION APPLICABILITY
1WARNING: DO NOT OPERATE THE DCHA IN AN ENCLOSED AREA SUCH
AS A GARAGE THAT DOES NOT HAVE EXHAUST VENTILATION FACILI-
TIES. ALWAYS VENT THE DCHA's EXHAUST WHEN OPERATING THE
DCHA. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN
PERSONAL INJURY OR DEATH.
Turn the ignition on.
With the DRBIIIt, attempt to communicate with the Cabin Heater Module.
Does the DRBIIItdisplay: No Response From Cabin Heater Module?All
Ye s®Refer to Communication for the related symptom.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
No®Go To 2
296
CABIN HEATER
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TEST ACTION APPLICABILITY
2WARNING: DO NOT OPERATE THE DCHA IN AN ENCLOSED AREA SUCH
AS A GARAGE THAT DOES NOT HAVE EXHAUST VENTILATION FACILI-
TIES. ALWAYS VENT THE DCHA's EXHAUST WHEN OPERATING THE
DCHA. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN
PERSONAL INJURY OR DEATH.
Turn the ignition on.
With the DRBIIIt, read Cabin Heater DTCs.
Is DTC B1813 Heater In Lockout Mode present?All
Ye s®Go To 3
No®Go To 4
3WARNING: DO NOT OPERATE THE DCHA IN AN ENCLOSED AREA SUCH
AS A GARAGE THAT DOES NOT HAVE EXHAUST VENTILATION FACILI-
TIES. ALWAYS VENT THE DCHA's EXHAUST WHEN OPERATING THE
DCHA. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN
PERSONAL INJURY OR DEATH.
Start the engine.
Allow the engine to idle.
Turn the A/C - Heater Control Module's Power switch on.
Turn the Blower switch to the high speed position.
Set the Blend Control to the max heat position.
Remove Cabin Heater Fuse #15 from the IPM for a minimum of five seconds, then
reinstall the fuse. The DCHA may attempt to start.
Turn the Blower switch off and turn the A/C - Heater Control Module's Power switch
off.
Turn the engine off.
View repairAll
Repair
Go To 4
297
CABIN HEATER
CABIN HEATER PRE-TEST ÐContinued
Page 327 of 4284

TEST ACTION APPLICABILITY
4WARNING: DO NOT OPERATE THE DCHA IN AN ENCLOSED AREA SUCH
AS A GARAGE THAT DOES NOT HAVE EXHAUST VENTILATION FACILI-
TIES. ALWAYS VENT THE DCHA's EXHAUST WHEN OPERATING THE
DCHA. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN
PERSONAL INJURY OR DEATH.
WARNING: ALLOW THE DCHA ASSEMBLY TO COOL BEFORE PERFORM-
ING A COMPONENT INSPECTION/REPAIR/REPLACEMENT. FAILURE TO
FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.
NOTE: The DCHA Control will store up to three DTCs in its memory.
NOTE: If the DCHA Control detects a new fault in the DCHA system, one
that is not already stored in its memory, the DCHA Control will clear the
oldest of the three stored DTCs, and it will store the new fault's DTC.
NOTE: If the DCHA control detects a reoccurrence of a stored fault, the
DCHA control will overwrite that fault's DTC with the most recent occur-
rence.
Turn the ignition on.
Set the Blend Control to the max cool position.
Turn the A/C - Heater Control Module's Power switch off.
With the DRBIIIt, record and erase Cabin Heater and FCM DTCs.
Start the engine.
Allow the engine to idle.
Turn the A/C - Heater Control Module's Power switch on.
Turn the Blower switch to the high speed position.
CAUTION: Do not activate the DCHA Field Mode Test with the engine off.
Failure to follow these instructions may result in internal damage to the
DCHA Heater Module.
NOTE: Do not disconnect the vehicle's battery or the DCHA's main power
supply while the DCHA is in operation or in run-down mode. Failure to
follow these instructions may result in excess emissions from the DCHA
during heater operation.
With the DRBIIItin Cabin Heater, Systems Tests, select Field Mode and press Enter.
Set the Blend Control to the max heat position. Upon completion of the Field Mode
Test, proceed as follows:
With the DRBIIIt, read Cabin Heater and Active FCM DTCs.
Turn the Blower switch off and turn the A/C - Heater Control Module's Power switch
off.
Turn the engine off.
Are any DTCs present?All
Ye s®Return to the symptom list and choose the DTC(s). Diagnose and
repair all FCM faults prior to diagnosing DCHA faults. If DTC
B1813 Heater In Lockout Mode reset with other DTC(s), reset the
heater before diagnosing the other DTC(s).
Perform CABIN HEATER VERIFICATION TEST - VER 1.
No®Go To 5
5 Is the symptom Cabin Heater inoperable from the A/C - Heater Module? All
Ye s®Refer to symptom *Cabin Heater Inoperable From A/C - Heater
Module in the Cabin Heater category.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
No®Let DCHA cool. Inspect fuel line, intake & exhaust, & coolant
hoses for restrictions, obstructions, loose clamps, leakage, etc.
Check connectors. Clean & repair as necessary. Refer to Service
Manual for additional symptom based diagnosis, if necessary.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
298
CABIN HEATER
CABIN HEATER PRE-TEST ÐContinued
Page 328 of 4284

Symptom:
B1000 CONTROL UNIT ERRONEOUS
When Monitored and Set Condition:
B1000 CONTROL UNIT ERRONEOUS
When Monitored: During DCHA activation.
Set Condition: This DTC will set if a fault occurs with the DCHA Control Unit's memory.
POSSIBLE CAUSES
DCHA CONTROL UNIT FAULT
TEST ACTION APPLICABILITY
1WARNING: DO NOT OPERATE THE DCHA IN AN ENCLOSED AREA SUCH
AS A GARAGE THAT DOES NOT HAVE EXHAUST VENTILATION FACILI-
TIES. ALWAYS VENT THE DCHA's EXHAUST WHEN OPERATING THE
DCHA. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN
PERSONAL INJURY OR DEATH.
WARNING: ALLOW THE DCHA ASSEMBLY TO COOL BEFORE PERFORM-
ING A COMPONENT INSPECTION/REPAIR/REPLACEMENT. FAILURE TO
FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.
CAUTION: DO NOT PERFORM THIS TEST UNLESS DIRECTED HERE BY
THE CABIN HEATER PRE-TEST. ALWAYS PERFORM THE CABIN HEATER
PRE-TEST PRIOR TO PERFORMING ANY OTHER CABIN HEATER TEST
FOR THE RESULT TO BE VALID.
Turn the ignition off.
View repairAll
Repair
Replace the DCHA Heater Module in accordance with the Service
Information.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
299
CABIN HEATER