Diagnostic Procedure

WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.

P0071-AMBIENT TEMP SENSOR PERFORMANCE DIAGNOSTIC TEST REFERENCE

TEST	ACTION	APPLICABILITY
1	Ignition on, engine not running. With the DRBIII®, 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 . Perform POWERTRAIN VERIFICATION TEST VER - 5 .	All
2	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 C1 and C2 PCM harness connectors.Disconnect the Ambient Temp Sensor harness connector.Ignition on, engine not running.Using a 12-volt test light connected to ground probe the (G31) AAT Signal circuit at the Ambient Temp Sensor harness connector.Does the test light illuminate brightly?Yes --> Repair the short to voltage in the (G31) AAT Signal circuit.Perform POWERTRAIN VERIFICATION TEST VER - 5 .No --> Go To 3	All
3	Turn the ignition off. Connect the C1 and C2 PCM harness connectors. Ignition on, engine not running. With the DRBIII®, read the Ambient Temperature Sensor voltage. Is the voltage above 4.6 volts? Yes --> Go To 4 No --> Go To 7	All
4	Connect a jumper wire across the (G31) AAT Signal circuit and the (K900) Sensor ground circuit terminals of the Sensor harness connector. With the DRBIII®, read the AAT Sensor voltage. Is the voltage below 1.0 volt? Yes --> Replace the Ambient Temperature Sensor. Perform POWERTRAIN VERIFICATION TEST VER - 5 . No --> Go To 5 NOTE: Remove the jumper wire before continuing.	All
5	Turn the ignition off. Disconnect the C1 and C2 PCM harness connectors. 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 (G31) AAT Signal circuit from the AAT 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 (G31) AAT Signal circuit. Perform POWERTRAIN VERIFICATION TEST VER - 5 .	All
6	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 (K900) Sensor ground circuit from the AAT Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?Yes --> Go To 9No --> Repair the open in the (K900) Sensor ground circuit.Perform POWERTRAIN VERIFICATION TEST VER - 5 .	All
7	Turn the ignition off. Disconnect the C1 and C2 PCM harness connectors. Measure the resistance between ground and the (G31) AAT Signal circuit at the AAT Sensor harness connector. Is the resistance below 100 ohms? Yes --> Repair the short to ground in the (G31) AAT Signal circuit. Perform POWERTRAIN VERIFICATION TEST VER - 5 . No --> Go To 8	All
8	Measure the resistance between the (G31) AAT Signal circuit and the (K900) Sensor ground circuit at the AAT Sensor harness connector. Is the resistance below 100 ohms? Yes --> Repair the short between the (K900) Sensor ground circuit and the (G31) AAT Signal circuit. Perform POWERTRAIN VERIFICATION TEST VER - 5 . No --> Go To 9	All
9	NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.If there are no possible causes remaining, view repair.RepairReplace and program the Powertrain Control Module per Service Information.Perform POWERTRAIN VERIFICATION TEST VER - 5 .	All