Page 560 of 4284

TEST ACTION APPLICABILITY
9 Turn the ignition off.
Reconnect the Rear A/C Heater Unit harness connector.
Disconnect the Rear Mode Door Actuator harness connector.
Turn the ignition on.
With the DRB, erase the HVAC DTCs.
Cycle the ignition switch from off to on and monitor the HVAC DTCs. Note: make
sure the active DTCs are erased at this time.
Slowly turn the mode door knob through each of it's different positions. Perform this
step a few times.
Turn the mode door knob to the Panel, Bi-level, or Floor position.
Press and release the recirculation button. Perform this step a few times.
Slowly slide the front temperature control levers (if equipped with dual or three zone,
slide all front levers) from hot to cold and back to hot. Perform this step a few times.
Slowly turn the rear blend/mode door knob from hot to cold and back to hot. Perform
this step a few times.
With the DRB, read the active HVAC DTCs.
Did the overcurrent DTCs reset?All
Ye s®Repair the Rear A/C Heater Unit wiring harness for a short to
ground or shorted together door driver circuits between the Rear
A/C Heater Unit and the rear mode and blend doors.
Perform BODY VERIFICATION TEST - VER 1.
No®Replace the Rear Mode Door Actuator in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
531
HEATING & A/C
BLEND OVERCURRENT (ACTIVE) - MANUAL A/C ÐContinued
Page 571 of 4284

Symptom List:
FRONT AND REAR BLOWER OUTPUT 1 OPEN
FRONT AND REAR BLOWER OUTPUT 2 OPEN
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be FRONT AND REAR BLOWER
OUTPUT 1 OPEN.
When Monitored and Set Condition:
FRONT AND REAR BLOWER OUTPUT 1 OPEN
When Monitored: Continuously.
Set Condition: If the FCM detects no voltage present on the Front/Rear Blower Motor
Relay Control circuit.
FRONT AND REAR BLOWER OUTPUT 2 OPEN
When Monitored: Continuously.
Set Condition: If the FCM detects no voltage present on the Front/Rear Blower Motor
Relay Control circuit.
POSSIBLE CAUSES
CHECK DTCS
B+ CIRCUIT OPEN
FRONT AND REAR BLOWER RELAYS OPEN
FRONT/REAR BLOWER MOTOR RELAY CONTROL CIRCUIT SHORTED TO GROUND
FRONT/REAR BLOWER MOTOR RELAY CONTROL CIRCUIT OPEN
FRONT CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
NOTE: If neither DTC will reset or is active, refer to the wiring diagrams
located in the service information to help isolate a possible intermittent
condition.
With the DRB, read the FCM DTC's.
Are both the Front/Rear Blower Output 1 Open and the Front/Rear Blower Output
2 Open DTC's set?All
Ye s®Go To 2
No®Replace the Front Control Module (FCM) in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
542
HEATING & A/C
Page 572 of 4284

TEST ACTION APPLICABILITY
2 Remove either the Front Blower Motor Relay or the Rear Blower Motor Relay, if
equipped, from the IPM.
Using a 12-volt test light connected to ground, probe cavity 86 of the blower relay
connector.
Is the test light illuminated?All
Ye s®Go To 3
No®Check the B+ feed to the Intelligent Power Module (IPM) for an
open. If OK, replace the IPM in accordance with the Service
Information.
Perform BODY VERIFICATION TEST - VER 1.
3 Turn the ignition off.
Install a substitute relay in place of the existing Front Blower Motor Relay and the
existing Rear Blower Motor Relay, if equipped.
With the DRB, erase DTCs.
Turn the ignition off, wait 30 seconds, then turn the ignition on.
With the DRB, read DTCs.
Did these DTCs reset?All
Ye s®Go To 4
No®Replace the Front Blower Motor Relay and the Rear Blower
Motor Relay, if equipped.
Perform BODY VERIFICATION TEST - VER 1.
4 Turn the ignition off.
Remove the Front Control Module from the IPM.
Remove the Front Blower Motor Relay and the Rear Blower Motor Relay, if equipped,
from the IPM.
Measure the resistance between ground and the Front/Rear Blower Motor Relay
Control circuit (FCM connector cavity 30).
Is the resistance below 5.0 ohms?All
Ye s®Replace the Intelligent Power Module (IPM) in accordance with
the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 5
5 Turn the ignition off.
Remove the Front Control Module from the IPM.
Remove the Front Blower Motor Relay from the IPM.
Measure the resistance of the Front/Rear Blower Motor Relay Control circuit
between the FCM connector cavity 30 and the Front Blower Motor Relay connector
cavity 85.
Is the resistance below 5.0 ohms?All
Ye s®Replace the Front Control Module (FCM) in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No®Replace the Intelligent Power Module (IPM) in accordance with
the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
543
HEATING & A/C
FRONT AND REAR BLOWER OUTPUT 1 OPEN ÐContinued
Page 573 of 4284

Symptom List:
FRONT AND REAR BLOWER OUTPUT 1 SHORT TO BATT
FRONT AND REAR BLOWER OUTPUT 2 SHORT TO BATT
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be FRONT AND REAR BLOWER
OUTPUT 1 SHORT TO BATT.
When Monitored and Set Condition:
FRONT AND REAR BLOWER OUTPUT 1 SHORT TO BATT
When Monitored: With the ignition on.
Set Condition: The FCM detects excessive current when attempting to close the Front/
Rear Blower Motor Relays.
FRONT AND REAR BLOWER OUTPUT 2 SHORT TO BATT
When Monitored: With the ignition on.
Set Condition: The FCM detects excessive current when attempting to close the Front/
Rear Blower Motor Relays.
POSSIBLE CAUSES
CHECK DTCS
FRONT BLOWER MOTOR RELAY SHORTED
REAR BLOWER MOTOR RELAY SHORTED
FRONT/REAR BLOWER MOTOR RELAY CONTROL CIRCUIT SHORTED TO BATTERY
FRONT CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
NOTE: If neither DTC will reset or is active, refer to the wiring diagrams
located in the service information to help isolate a possible intermittent
condition.
With the DRB, read the FCM DTC's.
Are both of these DTCs set?All
Ye s®Go To 2
No®Replace the Front Control Module (FCM) in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
544
HEATING & A/C
Page 574 of 4284

TEST ACTION APPLICABILITY
2 Turn the ignition off.
Install a substitute relay in place of the existing Front Blower Motor Relay.
With the DRB, erase DTCs.
Turn the ignition on.
With the DRB, read DTCs.
Did these DTCs reset?All
Yes, equipped with rear blower motor
Go To 3
Yes, not equipped with rear blower motor
Go To 4
No®Replace the original Front Blower Motor Relay.
Perform BODY VERIFICATION TEST - VER 1.
3 Turn the ignition off.
Install a substitute relay in place of the existing Rear Blower Motor Relay.
With the DRB, erase DTCs.
Turn the ignition on.
With the DRB, read DTCs.
Did these DTCs reset?All
Ye s®Go To 4
No®Replace the original Rear Blower Motor Relay.
Perform BODY VERIFICATION TEST - VER 1.
4 Turn the ignition off.
Remove the Front Control Module from the IPM.
Remove the Front Blower Motor Relay and the Rear Blower Motor Relay, if equipped,
from the IPM.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the Front Blower Motor Relay
connector cavity 85.
Is the test light illuminated?All
Ye s®Replace the Intelligent Power Module (IPM) in accordance with
the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No®Replace the Front Control Module (FCM) in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
545
HEATING & A/C
FRONT AND REAR BLOWER OUTPUT 1 SHORT TO BATT ÐContinued
Page 589 of 4284
TEST ACTION APPLICABILITY
4 Turn the ignition on.
With the DRBIIIt, erase HVAC DTCs.
Cycle the ignition switch and wait approximately 1 minute.
With the DRBIIIt, read HVAC DTC's.
Did this DTC reset?All
Ye s®Replace the A/C - Heater Control Module in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No®Test Complete.
560
HEATING & A/C
TX FAILURE (ACTIVE) - MANUAL A/C ÐContinued
Page 594 of 4284

Symptom:
EL PANEL SHORT
POSSIBLE CAUSES
CHECK EXTERIOR ILLUMINATION
CHECK OPERATION OF ALL GAUGES
VERIFY CONCERN
PANEL LAMP DRIVER CIRCUIT SHORT TO GROUND
PANEL LAMP DRIVER OPEN CIRCUIT
OPEN GROUND CIRCUIT
BCM PANEL LAMP DRIVER CIRCUIT INTERNAL FAILURE
INSTRUMENT CLUSTER PANEL LAMPS DRIVER INTERNAL FAILURE
TEST ACTION APPLICABILITY
1 Ignition on, engine not running.
Turn the Headlamp Switch to the ON position.
Monitor the Instrument Cluster gauges for illumination.
Are any Instrument Cluster gauges illuminated?All
Ye s®Go To 3
No®Go To 2
2 Ignition on, engine not running.
Turn the Headlamp Switch to the ON position.
Monitor the Instrument Cluster gauges for illumination.
Are all of the Instrument Cluster gauges illuminated?All
Ye s®Go To 3
No®Replace the Instrument Cluster.
Perform BODY VERIFICATION TEST - VER 1.
3 Ignition on, engine not running.
Turn the headlamp switch to the ON position.
Monitor the Headlamps for illumination.
Are the Headlamps illuminated?All
Ye s®Go To 4
No®Refer to EXTERIOR ILLUMINATION for the related symp-
tom(s).
Perform BODY VERIFICATION TEST - VER 1.
4 Ignition on, engine not running.
With the DRBIIIt, erase DTCs.
Cycle the ignition switch from OFF to ON.
Wait 1 to 2 minutes for the system to cycle.
With the DRBIIIt, read DTCs.
Did the DTC reset?All
Ye s®Go To 5
No®Perform the Instrument Cluster Self-Test and verify the concern.
Perform BODY VERIFICATION TEST - VER 1.
565
INSTRUMENT CLUSTER
Page 601 of 4284

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