Test Procedure

WARNING: This page does not describe the selected car, but rather 34 other vehicles, including the 2019 Lincoln Navigator, 2019 Lincoln Nautilus, 2019 Lincoln MKZ, 2019 Lincoln MKT, and 2019 Lincoln MKC. However, it is still accessible from the selected car via links, so may be relevant.

FA1 CHECK FOR DTCS

Are DTCs P0071, P0072, P0073 or P0074 present?

Yes	No
GO to FA2.	RETURN to SYMPTOM CHARTS for further direction.

FA2 CHECK FOR AN OPEN

Ignition OFF.
For Fiesta,
AAT Sensor connector disconnected.
IPC connector disconnected.

Measure the resistance between:

(+) AAT Sensor Connector, Harness Side	(-) IPC Connector, Harness Side
AAT	AAT - Pin 20
SIGRTN	SIGRTN - Pin 19

For all others,
AAT Sensor connector disconnected.
PCM connector disconnected.
Measure the resistance between:

(+) AAT Sensor Connector, Harness Side	(-) PCM Connector, Harness Side
AAT	AAT
SIGRTN	SIGRTN

Are the resistances less than 5 ohms?

Yes	No
GO to FA3.	REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test.

FA3 CHECK FOR A SHORT

Measure the resistance between:

(+) AAT Sensor Connector, Harness Side	(-)
AAT	Ground

Measure the resistance between:

(+) AAT Sensor Connector, Harness Side	(-) AAT Sensor Connector, Harness Side
AAT	SIGRTN

Is the resistance greater than 10K ohms?

Yes	No
GO to FA4.	REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test.

FA4 CHECK FOR A SHORT TO VOLTAGE

Ignition ON, engine OFF.
Measure the voltage between:

(+) AAT Sensor Connector, Harness Side	(-)
AAT	Ground
SIGRTN	Ground

Is any voltage present?

Yes	No
REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test.	GO to FA5.

FA5 INTERMITTENT CHECK

Ignition OFF.
For Fiesta,
IPC connector connected.
For all others,
PCM connector connected.
For all others,
AAT Sensor connector connected.
Ignition ON, engine OFF.
Access the PCM and monitor the AAT_V (VOLT) PID.
While observing the PID, carry out the following:
- Wiggle the harness from the sensor to the module.
- Wiggle the connectors and make sure they seat correctly.
- Look for sudden changes in the PID value when the harness and connector are wiggled.

Is a concern present?

Yes	No
REPAIR as necessary. Clear the PCM DTCs. REPEAT the self-test.	GO to FA6.

FA6 CHECK THE RESISTANCE OF THE AAT SENSOR

NOTE: Verify the external temperature of the sensor is at ambient temperature. Refer to the chart at the beginning of this test for the temperature and resistance values.

Ignition OFF.
AAT Sensor connector disconnected.
Measure the resistance between:

(+) AAT Sensor Connector, Component Side	(-) AAT Sensor Connector, Component Side
AAT	SIGRTN

Is the resistance within specification?

Yes	No
For Fiesta, GO to FA7. For all others, The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.	INSTALL a new AAT sensor. REFER to the appropriate Service Information. RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) . Clear the PCM DTCs. REPEAT the self-test.

FA7 CHECK FOR CORRECT INSTRUMENT PANEL CLUSTER (IPC) OPERATION

Disconnect all the IPC connectors.
Visually inspect for:
- pushed out pins
- corrosion
Connect all the IPC connectors and make sure they seat correctly.
Operate the system and verify the concern is still present.

Is the concern still present?

Yes	No
INSTALL a new IPC. REFER to the Instrumentation, Message Center, and Warning Chimes article.	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.