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Symptom:
*NO RESPONSE FROM TRANSMISSION CONTROL MODULE
POSSIBLE CAUSES
CHECK POWERS AND GROUNDS TO THE TRANSMISSION CONTROL MODULE
RADIO
K-TCM, RADIO CIRCUIT SHORTED TO GROUND
RADIO
K-TCM, RADIO CIRCUIT SHORTED TO VOLTAGE
K-TCM, RADIO CIRCUIT OPEN
TRANSMISSION CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Disconnect the Transmission Control Module harness connectors.
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 NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 2
2 Turn the ignition off.
Disconnect the TCM harness connectors.
Disconnect the DRBIIItfrom the DLC.
Measure the resistance between ground and the K-TCM, RADIO 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 Radio harness connector.
Measure the resistance between ground and the K-TCM, RADIO circuit.
Is the resistance below 5.0 ohms?All
Ye s!Repair the K-TCM, RADIO circuit for a short to ground.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Replace the Radio in accordance with the service information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
126
COMMUNICATION
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TEST ACTION APPLICABILITY
4 Turn the ignition off.
Disconnect the DRBIIItfrom the DLC.
Disconnect the TCM harness connectors.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the K-TCM, RADIO 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 Radio harness connectors.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the K-TCM, RADIO 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!Repair the K-TCM, RADIO circuit for a short to voltage.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Replace the Radio in accordance with the service information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
6 Turn the ignition off.
Disconnect the TCM harness connectors.
Disconnect the DRBIIItfrom the DLC.
Measure the resistance of the K-TCM, RADIO circuit between the TCM connector
and the DLC.
Is the resistance below 5.0 ohms?All
Ye s!Replace the Transmission Control Module in accordance with the
Service Information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Repair the K-TCM, RADIO circuit for an open.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
127
COMMUNICATION
*NO RESPONSE FROM TRANSMISSION CONTROL MODULE ÐContinued
Page 141 of 2305

Symptom:
A/C COMPRESSOR CONTROL HIGH OR OPEN (ACTIVE)
POSSIBLE CAUSES
A/C COMPRESSOR CLUTCH CONTROL CIRCUIT SHORTED TO VOLTAGE
A/C COMPRESSOR CLUTCH
A/C COMPRESSOR CLUTCH CONTROL CIRCUIT OPEN
AUTOMATIC TEMPERATURE CONTROL (ATC)
TEST ACTION APPLICABILITY
1 Turn the ignition off.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the A/C Compressor Clutch harness connector.
Turn the ignition on.
Press the Air Conditioning switch off.
Measure the voltage of the A/C Compressor Clutch Control circuit.
Is the voltage above 10.0 volts?All
Ye s!Go To 2
No!Go To 4
2 Turn the ignition off.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Disconnect the A/C Compressor Clutch harness connector.
Turn the ignition on.
Measure the voltage of the A/C Compressor Clutch Control circuit.
Is the voltage above 0.2 volts?All
Ye s!Repair the A/C Compressor Clutch Control circuit for a short to
voltage.
Perform BODY VERIFICATION TEST - VER 1.
No!Go To 3
3 Turn the ignition off.
NOTE: Check connectors - Clean/repair as necessary.
Reconnect the Automatic Temperature Control (ATC) C1 harness connector.
Reconnect the A/C Compressor Clutch harness connector.
Verify that the A/C Compressor Clutch Ground is clean and tight.
Turn the ignition on.
With the DRBIIIt, erase DTCs.
Turn the ignition off, wait 5 seconds, then turn the ignition on.
With the DRBIIIt, read Automatic Temperature Control DTCs.
Does the DRBIIItdisplay: A/C COMPRESSOR CONTROL HIGH OR OPEN?All
Ye s!Replace the A/C Compressor Clutch in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No!Test Complete.
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HEATING & A/C
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TEST ACTION APPLICABILITY
4 Turn the ignition off.
NOTE: Check connectors - Clean/repair as necessary.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Disconnect the A/C Compressor Clutch harness connector.
Measure the resistance of the A/C Compressor Clutch Control circuit between the
Automatic Temperature Control (ATC) C1 harness connector and the A/C Compres-
sor Clutch harness connector.
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 A/C Compressor Clutch Control circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
129
HEATING & A/C
A/C COMPRESSOR CONTROL HIGH OR OPEN (ACTIVE) ÐContinued
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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.
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HEATING & A/C
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NO COMMUNICATION WITH IC (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 Instrument Cluster.
POSSIBLE CAUSES
CHECK FOR ACTIVE AUTOMATIC TEMPERATURE CONTROL (ATC) DTCS
INTERMITTENT CONDITION
TEST ACTION APPLICABILITY
1NOTE: 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 any DTCs?All
Ye s!Return to the Heating & A/C Symptom List and choose the
symptom(s).
Perform BODY VERIFICATION TEST - VER 1.
No!Using the wiring diagram/schematic as a guide, inspect the
wiring and connectors related to the circuit(s) that caused the
original DTC(s) to set.
Perform BODY VERIFICATION TEST - VER 1.
131
HEATING & A/C
A/C COMPRESSOR CONTROL HIGH OR OPEN (STORED) ÐContinued
Page 145 of 2305

Symptom:
A/C COMPRESSOR CONTROL SHORTED LOW (ACTIVE)
POSSIBLE CAUSES
A/C COMPRESSOR CLUTCH
A/C COMPRESSOR CLUTCH CONTROL CIRCUIT SHORTED TO GROUND
A/C COMPRESSOR CLUTCH CONTROL CIRCUIT SHORTED TO GROUND CIRCUIT
A/C COMPRESSOR CLUTCH CONTROL CIRCUIT SHORTED TO SENSOR GROUND CIRCUIT
AUTOMATIC TEMPERATURE CONTROL (ATC)
TEST ACTION APPLICABILITY
1 Turn the ignition on.
Press the Air Conditioning switch off.
Turn the ignition off.
Disconnect the A/C Compressor Clutch harness connector.
Turn the ignition on.
With the DRBIIIt, record and erase Automatic Temperature Control DTCs.
Turn the ignition off, wait 5 seconds, then turn the ignition on.
With the DRBIIIt, read the Automatic Temperature Control DTCs.
Does the DRBIIItdisplay: A/C COMPRESSOR CONTROL HIGH OR OPEN?All
Ye s!Replace the A/C Compressor Clutch in accordance with the
Service Information.
Perform BODY VERIFICATION TEST - VER 1.
No!Go To 2
2 Turn the ignition off.
Disconnect the A/C Compressor Clutch harness connector.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Measure the resistance between ground and the A/C Compressor Clutch Control
circuit.
Is the resistance below 10k ohms?All
Ye s!Repair the A/C Compressor Clutch Control circuit for a short to
ground.
Perform BODY VERIFICATION TEST - VER 1.
No!Go To 3
3 Turn the ignition off.
Disconnect the A/C Compressor Clutch harness connector.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Measure the resistance between the A/C Compressor Clutch Control circuit and the
Ground circuit in the Automatic Temperature Control C1 harness connector.
Is the resistance below 10k ohms?All
Ye s!Repair the A/C Compressor Clutch Control circuit for a short to
the Ground circuit.
Perform BODY VERIFICATION TEST - VER 1.
No!Go To 4
132
HEATING & A/C
Page 146 of 2305
TEST ACTION APPLICABILITY
4 Turn the ignition off.
Disconnect the A/C Compressor Clutch harness connector.
Disconnect the Automatic Temperature Control (ATC) C1 harness connector.
Measure the resistance between the A/C Compressor Clutch Control circuit and the
Sensor Ground circuit in the Automatic Temperature Control C1 harness connector.
Is the resistance below 10k ohms?All
Ye s!Repair the A/C Compressor Clutch 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.
133
HEATING & A/C
A/C COMPRESSOR CONTROL SHORTED LOW (ACTIVE) ÐContinued