Test Procedure
- DA1 PRELIMINARY DIAGNOSIS
Are DTCs P009A, P0111, P0112, P0113, P0114, or P1112 present?
Yes No For DTCs P009A, P0111, P0112, P0113, P0114 or P1112, GO to DA2.
For all others, GO to DIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .For symptoms without DTCs, GO to DA2. - DA2 CHECK FOR AN OPEN IN THE HARNESS NOTE: Only measure the circuits that apply to the vehicle being diagnosed. Refer to the appropriate Wiring Diagram for the MAF/IAT sensor to determine which circuits to measure.
- Ignition OFF.
- IAT Sensor connector disconnected.
- PCM connector disconnected.
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) IAT Sensor Connector, Harness Side (-) SIGRTN Ground - Measure the resistance between:RESISTANCE REFERENCE CHART
(+) IAT Sensor Connector, Harness Side (-) PCM Connector, Harness Side IAT IAT SIGRTN SIGRTN SIGRTN MAF RTN
Are the resistances less than 5 ohms?
Yes No GO to DA3. REPAIR the open circuit. Clear the PCM DTCs. REPEAT the self-test. - DA3 CHECK FOR A SHORT BETWEEN CIRCUITS IN THE HARNESS
- Measure the resistance between:RESISTANCE REFERENCE CHART
(+) IAT Sensor Connector, Harness Side (-) IAT Ground - Measure the resistance between:RESISTANCE REFERENCE CHART
(+) IAT Sensor Connector, Harness Side (-) IAT Sensor Connector, Harness Side IAT VPWR IAT MAF RTN IAT SIGRTN IAT MAF
Are the resistances greater than 10K ohms?
Yes No GO to DA4. REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. - Measure the resistance between:
- DA4 CHECK FOR A SHORT TO VOLTAGE IN THE HARNESS
- Ignition ON, engine OFF.
- Measure the voltage between:VOLTAGE REFERENCE CHART
(+) IAT Sensor Connector, Harness Side (-) IAT Ground
Is any voltage present?
Yes No REPAIR the short circuit. Clear the PCM DTCs. REPEAT the self-test. GO to DA5. - DA5 INTERMITTENT CHECK
- Ignition OFF.
- PCM connector connected.
- IAT Sensor connector connected.
- Ignition ON, engine OFF.
- Access the PCM and monitor the IAT (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 IAT sensor and wiggle the harness connector to simulate road shock.
Does the IAT PID reading change?
Yes No REPAIR as necessary or INSTALL a new IAT sensor. REFER to the appropraite Electronic Engine Controls . RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
REPEAT the self-test.GO to DA6. - DA6 INTAKE AIR TEMPERATURE (IAT) SENSOR AMBIENT AIR TEMPERATURE (AAT) SENSOR CORRELATION NOTE: Check temperature values while engine is at ambient temperature, cold soak the engine for a minimum of 8 hours while not in direct sun light, if necessary.
- Ignition ON, engine OFF.
- Access the PCM and monitor the IAT (TEMP) PID.
- For Fiesta,
- Access the PCM and monitor the OUTDR_TMP (TEMP) PID.
- For all others,
- Access the PCM and monitor the AAT (TEMP) PID.
Are the temperature readings within 18°C (32.4°F) of each other?
Yes No GO to DA7. INSTALL a new IAT sensor. REFER to the appropriate Electronic Engine Controls articles . RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
REPEAT the self-test. - DA7 CHECK THE IAT CIRCUIT VOLTAGE CYCLING INTEGRITY
- Ignition OFF.
- IAT Sensor connector disconnected.
- Ignition ON, engine OFF.
- Access the PCM and monitor the IAT (VOLT) PID.
- Record the IAT PID value.
- Connect a 5 amp fused jumper wire between the following:CONNECTOR PINS REFERENCE CHART
Point A IAT Sensor Connector, Harness Side Point B IAT Sensor Connector, Harness Side IAT SIGRTN - Record the IAT PID value.
Does the IAT PID change from greater than 3.0 volts to less than 0.20 volt when the jumper is connected?
Yes No INSTALL a new IAT sensor. REFER to the appropriate Electronic Engine Controls article . RESET the keep alive memory (KAM). REFER to RESETTING THE KEEP ALIVE MEMORY (KAM) .
REPEAT the self-test.GO to DA8. - DA8 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) , PROGRAMMING THE VID BLOCK FOR A REPLACEMENT PCM . The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.