
Symptom:
REAR KEYBOARD FAULT (ACTIVE)
POSSIBLE CAUSES
BCM
IGNITION SWITCH (RUN) CIRCUIT OPEN
KDB CLOCK CIRCUIT SHORTED TO VOLTAGE
KDB DATA CIRCUIT SHORTED TO GROUND
KDB DATA CIRCUIT SHORTED TO VOLTAGE
KDB CLOCK CIRCUIT SHORTED TO GROUND
KDB DATA CIRCUIT OPEN
ATC - KDB DATA CIRCUIT FAULT
KDB CLOCK CIRCUIT OPEN
ATC - KDB CLOCK CIRCUIT FAULT
REAR ATC SWITCH GROUND CIRCUIT OPEN
REAR AUTOMATIC TEMPERATURE CONTROL SWITCH
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Measure the resistance of the Rear ATC Switch Ground circuit.
Is the resistance below 5.0 ohms?All
Ye s®Go To 2
No®Repair the Rear ATC Switch Ground circuit for an open.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
2 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Turn the ignition on.
Measure the voltage of the Ignition Switch (Run) circuit.
Is the voltage above 10.0 volts?All
Ye s®Go To 3
No®Go To 14
3 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Turn the ignition on.
Measure the voltage of the KDB Data circuit.
Is the voltage above 10.0 volts?All
Ye s®Go To 4
No®Go To 11
280
AUTOMATIC TEMPERATURE CONTROL

TEST ACTION APPLICABILITY
4 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Disconnect the ATC C2 harness connector.
Turn the ignition on.
Measure the voltage of the KDB Data circuit.
Is the voltage above 1.0 volt?All
Ye s®Repair the KDB Data circuit for a short to voltage.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 5
5 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Use Scope input cable CH7058, Cable to Probe adapter CH7062, and the red and
black test probes.
Connect the scope input cable to the channel one connector on the DRB. Attach the
red and black leads and the cable to probe adapter to the scope input cable.
Select Lab Scope.
Select Live.
Select 12 volt square wave.
Press F2 for Scope.
Press F2 and use the arrows to set the voltage range to 20 volts, the Offset to 4.0, and
the Probe to x10. Press F2 again and set the divisions to 40ms/Div, then press F2
again when complete.
Connect the Black lead to the chassis ground. Connect the Red lead to the KDB Clock
circuit in the Rear Automatic Temperature Control Switch harness connector.
Turn the ignition on.
Observe the voltage display on the DRB Lab Scope.
NOTE: The lab scope pattern should look similar to the example given in the
support material and cycle from approximately 0 volts to 8.0 volts.
Did the lab scope pattern and voltage react as noted above?All
Ye s®Go To 6
No®Go To 7
6 If there are no possible causes remaining, view repair. All
Repair
Replace the Rear Automatic Temperature Control Switch.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
7 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Disconnect the ATC C2 harness connector.
Turn the ignition on.
Measure the voltage of the KDB Clock circuit.
Is the voltage above 1.0 volt?All
Ye s®Repair the KDB Clock circuit for a short to voltage.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 8
281
AUTOMATIC TEMPERATURE CONTROL
REAR KEYBOARD FAULT (ACTIVE) ÐContinued

TEST ACTION APPLICABILITY
8 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Disconnect the ATC C2 harness connector.
Measure the resistance between ground and the KDB Clock circuit.
Is the resistance above 100k ohms?All
Ye s®Go To 9
No®Repair the KDB Clock circuit for a short to ground.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
9 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Disconnect the ATC C2 harness connector.
Measure the resistance of the KDB Clock circuit.
Is the resistance below 5.0 ohms?All
Ye s®Go To 10
No®Repair the KDB Clock circuit for an open.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
10 If there are no possible causes remaining, view repair. All
Repair
Replace the ATC.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
11 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Disconnect the ATC C2 harness connector.
Measure the resistance between ground and the KDB Data circuit.
Is the resistance above 100k ohms?All
Ye s®Go To 12
No®Repair the KDB Data circuit for a short to ground.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
12 Turn the ignition off.
Disconnect the Rear Automatic Temperature Control Switch harness connector.
Disconnect the ATC C2 harness connector.
Measure the resistance of the KDB Data circuit.
Is the resistance below 5.0 ohms?All
Ye s®Go To 13
No®Repair the KDB Data circuit for an open.
With the DRBIIIt, reset the ATC after repair/replacement is
complete.
Perform BODY VERIFICATION TEST - VER 1.
282
AUTOMATIC TEMPERATURE CONTROL
REAR KEYBOARD FAULT (ACTIVE) 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.
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

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

Symptom:
B1813 HEATER IN LOCKOUT MODE
When Monitored and Set Condition:
B1813 HEATER IN LOCKOUT MODE
When Monitored: During DCHA activation.
Set Condition: This DTC will set if six continuous attempts to start heater operation fail
due to one or more faults in the DCHA system.
POSSIBLE CAUSES
B1813 AND ADDITIONAL DTC(S) PRESENT
B1813 RESET, NO ADDITIONAL DTC(S) PRESENT
B1813 CLEARED, ADDITIONAL DTC(S) PRESENT
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.
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 2
313
CABIN HEATER

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:
*KEY IN IGNITION AND DRIVER'S DOOR OPEN CHIME NOT
OPERATING PROPERLY
POSSIBLE CAUSES
DRIVER DOOR AJAR STATUS
IGNITION SWITCH
BODY CONTROL MODULE
TEST ACTION APPLICABILITY
1 Open the driver door.
With the DRB, in Input/Outputs, read the9DR DOOR AJAR SW9state.
Does the DRB display9DR DOOR AJAR SW: CLOSED9?All
Ye s®Go To 2
No®Refer to symptom list for problems related to Door Ajar.
Perform BODY VERIFICATION TEST - VER 1.
2 With the DRBIIItin Inputs/Outputs, read the Key in Ign Sw state while inserting
the key in and out of the ignition switch.
Does the DRBIIItdisplay change from open to closed?All
Ye s®Replace and program the Body Control Module in accordance
with the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No®Check the Ignition Lock Cylinder for damage. If OK replace the
Ignition Switch.
Perform BODY VERIFICATION TEST - VER 1.
336
CHIME