
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.
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.
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 CABIN HEATER VERIFICATION TEST - VER 1.
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.
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.
Turn the ignition on.
CAUTION: Do not actuate the Dosing Pump more than two times. Doing so
will put excess fuel in the DCHA Heater Module and cause smoke to emit
from the DCHA exhaust pipe when heater activation occurs.
With the DRBIIItin Actuators, select Dosing Pump. Listen for the pump to run. A
clicking noise should be heard coming from the pump.
Press Page Back and select No to stop the Dosing Pump actuation.
Does the Dosing Pump run when actuated?All
Ye s®Go To 3
No®Replace the Dosing Pump in accordance with the Service Infor-
mation.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
301
CABIN HEATER
B1800 NO START ÐContinued

TEST ACTION APPLICABILITY
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.
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.
Turn the ignition off.
Inspect the DCHA fuel line exterior for restrictions, leakage, and damage.
Verify that the DCHA 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 fuel line. Refer to Fuel Line, Cleaning in the Service
Information.
Is the DCHA fuel line Ok?All
Ye s®Go To 4
No®Repair the DCHA fuel line as necessary in accordance with the
Service Information.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
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.
Turn the ignition off.
Disconnect the Dosing Pump rubber insulators from the splash shield.
Disconnect the fuel line from the fuel outlet side of the Dosing Pump.
Using a suitable length of fuel line, connect one end to the fuel outlet side of the
Dosing Pump and place the other end in a suitable container.
Turn the ignition on.
CAUTION: For the result of this test to be valid, actuate the Dosing Pump
Prime twice if the DCHA fuel supply line was drained and then not primed
prior to performing this test.
NOTE: Allow the Dosing Pump Prime to run the full 45 seconds.
With the DRBIIItin System Tests, select Dosing Pump Prime.
When the Dosing Pump Prime is complete, measure the amount of fuel in the
container.
Does the Dosing Pump output approx 14 ml (0.5 oz) of fuel in a single Dosing Pump
Prime activation?All
Ye s®Go To 5
No®Replace the Dosing Pump in accordance with the Service Infor-
mation.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
302
CABIN HEATER
B1800 NO START ÐContinued

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.
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 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.
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
Yes, B1813 & Other DTC(s) Present
Return to the symptom list and choose the additional DTC(s) first,
then diagnose B1813.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
Yes, B1813 Reset with No Other DTC(s)
Allow DCHA to cool. Inspect DCHA intake & exhaust pipes for
restrictions & obstructions. Repair as necessary. After repair,
repeat Test 2 of this procedure. If intake & exhaust pipes are Ok,
replace DCHA Heater Module in accordance with Service Info.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
Yes, B1813 Cleared, Other DTC(s) Present
Return to the symptom list and choose the DTC(s).
Perform CABIN HEATER VERIFICATION TEST - VER 1.
No®Allow DCHA to cool. Inspect fuel line & coolant hoses for restric-
tions, obstructions, loose clamps, leakage, etc. Repair as neces-
sary. Check connectors. Clean & repair as necessary. Refer to
Service Manual for additional symptom diagnosis, if necessary.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
314
CABIN HEATER
B1813 HEATER IN LOCKOUT MODE ÐContinued

Symptom:
*CABIN HEATER INOPERABLE FROM A/C - HEATER MODULE
POSSIBLE CAUSES
DCHA ACTIVATION CRITERIA NOT MET
ATTEMPT TO COMMUNICATE WITH THE FCM AND THE HVAC MODULE
FCM OR HAVC DTCS PRESENT
VERIFY DCHA IS INOPERABLE FROM A/C - HEATER MODULE
A/C - HEATER CONTROL MODULE 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.
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.
Verify that all of the following criteria was met during the attempt to activate the
DCHA from the A/C - Heater Control Module.
The engine was running.
The engine coolant temperature was below 66ÉC (151ÉF).
The vehicle's fuel tank had more than 1/8 of a tank of fuel.
The A/C - Heater Control Module's Power switch was on.
The Blend Control was set above 95% reheat.
Was all criteria met during the attempt to activate the DCHA from the A/C - Heater
Control Module?All
Ye s®Go To 2
No®Attempt to activate the DCHA when all of the operating criteria
are met.
Perform CABIN HEATER VERIFICATION TEST - VER 1.
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, attempt to communicate with the FCM and the HVAC Module.
Was the DRBIIItable to communicate with the FCM and the HVAC Module?All
Ye s®Go To 3
No®Refer to Communication for the related symptom(s)
Perform CABIN HEATER VERIFICATION TEST - VER 1.
332
CABIN HEATER

NO BCM MESSAGE RECEIVED (STORED) - MANUAL A/C
When Monitored: With the igntion on.
Set Condition: If the A/C - Heater Control Module does not receive the dimming function
message from the BCM for more than 5 seconds, then the A/C - Heater Control Module
LEDs will default to full brightness and the DTC will set.
NO PCM MESSAGE RECEIVED (STORED) - MANUAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the A/C - Heater Control Module does not see any
messages from the PCM for more than 5 seconds.
PCM COMMUNICATION FAILURE (STORED) - MANUAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the A/C - Heater Control Module does not receive the
Fuel message from the PCM for more than 5 seconds.
POWER FAULT (STORED) - MANUAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the Power switch stays closed for 10 minutes.
REAR BLEND OVERCURRENT (STORED) - MANUAL A/C
When Monitored: When actuator movement is requested.
Set Condition: All (Blend, Mode, Recirc, and Zone) Overcurrent DTCs will set if the A/C
- Heater Control Module detects an excessive current draw on the Common Door Drive
circuit(s).
REAR BLEND POT CIRCUIT OPEN (STORED) - MANUAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the Rear Blower Rear Control Switch, Rear Blend
Potentiometer/circuit is open.
REAR BLEND POT CIRCUIT SHORT (STORED) - MANUAL A/C
When Monitored: When the ignition is on.
Set Condition: This DTC will set if the Rear Blower Rear Control Switch, Rear Blend
Potentiometer/5 Volt Supply/Rear Temperature Feedback Signal circuit is shorted low or
high.
REAR DEFOG FAILURE (STORED) - MANUAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the Rear Window Defogger switch stays closed for 10
minutes.
516
HEATING & A/C
A/C FAULT (STORED) - MANUAL A/C ÐContinued

Symptom List:
NO PCM MESSAGE RECEIVED (ACTIVE) - MANUAL A/C
PCM COMMUNICATION FAILURE (ACTIVE) - MANUAL A/C
VEHICLE ODOMETER FAILURE (ACTIVE) - MANUAL A/C
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be NO PCM MESSAGE RECEIVED
(ACTIVE) - MANUAL A/C.
When Monitored and Set Condition:
NO PCM MESSAGE RECEIVED (ACTIVE) - MANUAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the A/C - Heater Control Module does not see any
messages from the PCM for more than 5 seconds.
PCM COMMUNICATION FAILURE (ACTIVE) - MANUAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the A/C - Heater Control Module does not receive the
Fuel message from the PCM for more than 5 seconds.
VEHICLE ODOMETER FAILURE (ACTIVE) - MANUAL A/C
When Monitored: With the ignition on.
Set Condition: This DTC will set if the A/C - Heater Control Module does not receive the
Vehicle Odometer message from the PCM for more than 5 seconds.
POSSIBLE CAUSES
MESSAGE NOT RECEIVED
ATTEMPT TO COMMUNICATE WITH THE PCM/ECM
PCI BUS CIRCUIT OPEN
POWERTRAIN/ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, enter HVAC, System Tests then PCM Monitor.
Does the DRBIIItdisplay: PCM is active on BUS?All
Ye s®Replace the A/C - Heater Control Module in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 2
547
HEATING & A/C

Symptom:
FUEL GAUGE CHECKSUM FAILURE
POSSIBLE CAUSES
EMIC - INTERNAL ERROR
TEST ACTION APPLICABILITY
1 If there are no possible causes remaining, view repair. All
Repair
Replace the EMIC.
Perform BODY VERIFICATION TEST - VER 1.
571
INSTRUMENT CLUSTER

Symptom:
FUEL LEVEL SENDING UNIT INPUT OPEN
When Monitored and Set Condition:
FUEL LEVEL SENDING UNIT INPUT OPEN
When Monitored: With the ignition on.
Set Condition: Fuel Level Input to the BCM is greater than 9.8 volts for greater than 62.5
milliseconds.
POSSIBLE CAUSES
INTERMITTENT CONDITION
FUEL LEVEL SENSOR SIGNAL SHORTED TO B+
GROUND CIRCUIT OPEN
FUEL LEVEL SENDING UNIT OPERATION
FUEL LEVEL SENSOR SIGNAL CIRCUIT OPEN
BCM
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, erase DTCs.
Cycle the ignition off and on, leaving ignition key on for at least 15 seconds.
With the DRBIIItin Body Computer, read DTCs.
Does the DTC reset?All
Ye s®Go To 2
No®Go To 7
2 Turn the ignition off.
Disconnect the Fuel Tank Module harness connector.
Turn the ignition on.
NOTE: The BCM sends out a low current 12 volt signal on the Fuel Level
Sensor Signal circuit. This low current should not illuminate a 12 volt test
light.
Using a 12-volt test light connected to ground, probe the Fuel Level Sensor Signal
circuit in the Fuel Tank Module harness connector.
Does the test light illuminate?All
Ye s®Repair the Fuel Level Sensor Signal circuit shorted to battery
voltage.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 3
572
INSTRUMENT CLUSTER