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When Monitored and Set Condition:
P0071-AMBIENT TEMP SENSOR PERFORMANCE
When Monitored: Engine off time is greater than 480 minutes. Ambient temperature is greater than 4°C (39°F).
Set Condition: After a calibrated amount of cool down time, the PCM compares the ECT Sensor, IAT Sensor and the Ambient Air Temperature Sensor values. If the Ambient Air Temperature Sensor value is not within 10°C (18°F) of the other two temperature sensors an error is detected.
POSSIBLE CAUSES
GOOD TRIP EQUAL TO ZERO
(K25) AAT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
AMBIENT AIR TEMPERATURE SENSOR VOLTAGE BELOW 1.0 VOLT
(K25) AAT SIGNAL CIRCUIT OPEN
(K4) SENSOR GROUND CIRCUIT OPEN
(K25) AAT SIGNAL CIRCUIT SHORTED TO GROUND
(K25) AAT SIGNAL CIRCUIT SHORTED TO (K4) SENSOR GROUND
PCM LOW
PCM HIGH
TEST 1 -ACTION APPLICABILITY
Ignition on, engine not running.
With the DRBIIIt, read DTCs and record the related Freeze Frame data.
Is the Good Trip Counter displayed and equal to zero?
Yes ! Go To 2
No ! Refer to the INTERMITTENT CONDITION symptom in the Driveability category.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
TEST 2 ACTION APPLICABILITY
NOTE: Visually inspect both the component and the PCM connectors. Look for damage, partially broken wires and backed out or corroded terminals Turn the ignition off. Disconnect the Ambient Air Temp Sensor harness connector. Ignition on, engine not running. Measure the voltage of the (K25) AAT Signal circuit in the Ambient Air Temperature Sensor harness connector.
Is the voltage above 5.2 volts?
Yes ! Repair the short to battery voltage in the (K25) AAT Signal
circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Go To 3
TEST 3 =-
Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor harness connector.
Ignition on, engine not running.
With the DRBIIIt, read the Ambient Air Temperature Sensor voltage.
Is the voltage above 4.9 volts?
Yes ! Go To 4
No ! Go To 7
TEST 4
Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor harness connector.
Using a jumper wire, jumper across the Ambient Air Temperature Sensor harness connector.
Ignition on, engine not running.
With the DRBIIIt, read the Ambient Air Temperature voltage.
Is the voltage below 1.0 volt?
Yes ! Replace the Ambient Air Temperature Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Go To 5
TEST 5
Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor harness connector.
Disconnect the PCM harness connector.
CAUTION: DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING
THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMINALS
RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL
MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
Measure the resistance of the (K25) AAT Signal circuit from the Ambient Air Temperature Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes ! Go To 6
No ! Repair the open in the (K25) AAT Signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
TEST 6
Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor harness connector.
Disconnect the PCM harness connector.
CAUTION: DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING
THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM TERMINALS
RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL
MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
Measure the resistance of the (K167) Sensor ground circuit from the Ambient Air Temperature Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes ! NOTE: Before continuing, check the PCM harness connector
terminals for corrosion, damage, or terminal push out. Repair as
necessary. Replace and program the Powertrain Contorl Module
in accordance with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Repair the open in the (K4) Sensor ground circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
TEST 7
Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor harness connector.
Disconnect the PCM harness connector.
Measure the resistance between ground and the (K25) AAT Signal circuit.
Is the resistance below 100 ohms?
Yes ! Repair the short to ground in the (K25) AAT Signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Go To 8
TEST 8
Turn the ignition off.
Disconnect the Ambient Air Temperature Sensor harness connector.
Disconnect the PCM harness connector.
Measure the resistance between the (K25) AAT Signal circuit and the (K4) Sensor ground circuit in the Ambient Air Temperature Sensor harness connector.
Is the resistance below 100 ohms?
Yes ! Repair the Sensor ground shorted to the (K25) AAT Signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! NOTE: Before continuing, check the PCM harness connector
terminals for corrosion, damage or terminal push out. Repair as
necessary. Replace and program the Powertrain Control Module
in accordance with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.