Test Procedure
- FB1 PRELIMINARY DIAGNOSIS NOTE: Diagnose any circuit DTCs before range or performance DTCs.
Is DTC P0071, P0072, P0073 or P0074 present?
Yes No GO to FB2. RETURN to SYMPTOM CHARTS for further direction. - FB2 CHECK FOR AN OPEN
- Ignition OFF.
- PCM connector disconnected.
- For C-MAX,
- Right Exterior Rear View Mirror Assembly connector disconnected.
- Measure the resistance between:
(+) Right Exterior Rear View Mirror Assembly Connector, Harness Side (-) PCM Connector, Harness Side AAT - Pin 9 AAT - Pin B33 SIGRTN - Pin 10 SIGRTN - Pin B45 - For all others,
- AAT Sensor connector disconnected.
- Measure the resistance between:
(+) AAT Sensor Connector, Harness Side (-) PCM Connector, Harness Side AAT - Pin 1 AAT - Pin B33 SIGRTN - Pin 2 SIGRTN - Pin B45
Are the resistances less than 5 ohms?
Yes No GO to FB3. REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - FB3 CHECK FOR A SHORT TO GROUND
- For C-MAX,
- Measure the resistance between:
(+) Right Exterior Rear View Mirror Assembly Connector, Harness Side (-) AAT - Pin 9 Ground - For all others,
- Measure the resistance between:
(+) AAT Sensor Connector, Harness Side (-) AAT - Pin 1 Ground
Is the resistance greater than 10K ohms?
Yes No GO to FB4. REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. - FB4 CHECK FOR A SHORT TO VOLTAGE
- Ignition ON, engine OFF.
- For C-MAX,
- Measure the voltage between:
(+) Right Exterior Rear View Mirror Assembly Connector, Harness Side (-) AAT - Pin 9 Ground - For all others,
- 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 FB5. - FB5 INTERMITTENT CHECK
- Ignition OFF.
- PCM connector connected.
- For C-MAX,
- Right Exterior Rear View Mirror Assembly 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, wiggle, shake, and bend small sections of the wiring harness working from the sensor to the PCM.
- Lightly tap on the AAT sensor and wiggle the harness connector to simulate road shock.
Is a concern present?
Yes No REPAIR as necessary.
Clear the PCM DTCs. REPEAT the self-test.GO to FB6. - FB6 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 resistance specifications.
- Ignition OFF.
- For C-MAX,
- Right Exterior Rear View Mirror Assembly connector disconnected.
- Measure the resistance between:
(+) Right Exterior Rear View Mirror Assembly Connector, Component Side (-) Right Exterior Rear View Mirror Assembly Connector, Harness Side AAT - Pin 9 SIGRTN - Pin 10 - For all others,
- AAT Sensor connector disconnected.
- Measure the resistance between:
(+) AAT Sensor Connector, Component Side (-) AAT Sensor Connector, Component Side AAT - Pin 1 SIGRTN - Pin 2
Is the resistance 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. For C-MAX, INSTALL a new Right Exterior Rear View Mirror Assembly. REFER to the Service Information, Rear View Mirrors.
For all others, INSTALL a new AAT sensor. REFER to the Service Information, Climate Control.
Clear the PCM DTCs. REPEAT the self-test.