Test Procedure

WARNING: This page is about a different car, the 2012 Ford Pickup, 2012 Ford F550 Super Duty, 2012 Ford F450 Super Duty, and 2012 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

FA1 PRELIMINARY DIAGNOSIS

NOTE: Diagnose circuit faults prior to range or performance faults.

Is DTC P0070, P0071, P0072 or P0073 present?

Yes	No
GO to FA2.	GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .

FA2 CHECK FOR AN OPEN IN THE HARNESS

Ignition OFF.
AAT Sensor connector disconnected.
PCM-B connector disconnected.

Measure the resistance between:

(+) AAT Sensor Connector, Harness Side	(-) PCM-B Connector, Harness Side
AAT - Pin 1	AAT - Pin 3

Is the resistance 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 BETWEEN CIRCUITS IN THE HARNESS

Measure the resistance between:

(+) AAT Sensor Connector, Harness Side	(-)
AAT - Pin 1	Ground

Measure the resistance between:

(+) AAT Sensor Connector, Harness Side	(-) AAT Sensor Connector, Harness Side
AAT - Pin 1	SIGRTN - Pin 2

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 IN THE HARNESS

Ignition ON, engine OFF.

Measure the voltage between:

(+) AAT Sensor Connector, Harness Side	(-)
AAT - Pin 1	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.
AAT Sensor connector connected.
PCM-B 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 all accessible harness from the AAT sensor to the PCM and lightly tap on the sensor.
- Wiggle the AAT sensor connector.
- Look for sudden changes in the voltage when the harness and connector are wiggled or when the AAT sensor is tapped.

Is a concern present?

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

FA6 TEMPERATURE SENSOR CORRELATION

NOTE: Check temperature values while engine is at ambient temperature, cold soak the engine for a minimum of 8 hours if necessary.

Ignition ON, engine OFF.
Access the PCM and monitor the AAT (TEMP), CAC_T (TEMP), IAT11 (TEMP), ECT2 (TEMP) and EGRT11 (TEMP) PIDs.
The AAT temperature must be within the following ranges:
- Within 10°C (18°F) degrees of the CAC_T reading
- Within 15°C (27°F) degrees of the IAT11 reading
- Within 20°C (36°F) degrees of the ECT2 reading
- Within 16°C (28.8°F) degrees of the EGRT11 reading

Is the AAT PID within specification?

Yes	No
Unable to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the concern. REPAIR as necessary.	INSTALL a new AAT sensor. REFER to the appropriate Climate Control System article. Clear the PCM DTCs. REPEAT the self-test. If the concern or DTC is still present, GO to FA7.

FA7 CHECK FOR CORRECT PCM OPERATION

Disconnect all the PCM connectors.
Visually inspect for:
- pushed out pins
- corrosion
Connect all the PCM connectors and make sure they seat correctly.
Carry out the PCM self-test.
Verify the concern is still present.

Is the concern still present?

Yes	No
INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) .	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.