Diagnostic Aids

Perform this test only when directed by QUICK TEST or other test. Values may vary up to 15 percent due to sensor and VREF variations.

This test is intended to diagnose the following components and circuits:

• MAF sensor.
• Harness circuits: MAF, VPWR and MAF REF.

1. 1) DTC P0100: Check MAF Signal TO PCM
   
   DTC P0100 indicates a malfunction in the MAF sensor circuit. Possible causes are as follows:
   • Faulty MAF sensor.
   • Open or short in harness.
   • Poor harness connection.
   • Air intake leak.
   • Faulty PCM.

   Turn ignition off. Check air intake system for leaks. Connect NGS scan tool to OBD-II DLC. Start engine and let idle (engine warm). Access MAF PID. If MAF PID reads 1-1.7 volts, go to step  30). If MAF PID reads one volt or less, go to next step. If MAF PID reads 1.7 volts or more, go to step  20).

   NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 1) to step 10). No test procedures have been omitted.
2. 10) Check VPWR At MAF
   
   Turn ignition off. Disconnect MAF sensor. Turn ignition on. Measure voltage between VPWR terminal at MAF sensor harness connector (Black/White wire) and ground. See Fig 1. Also see CIRCUIT PIN IDENTIFICATION  table. If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, repair VPWR circuit. See TEST B .
   Fig 1: MAF Sensor Circuit & Harness Connector Terminals

   Courtesy of FORD MOTOR CO.
3. 11) Check MAF Circuit Short To Ground
   
   Turn ignition off. Disconnect MAF sensor connector. Disconnect PCM. Measure resistance between terminal No. 52 (White/Blue wire) and terminal No. 53 (Blue/Orange wire), and PCM ground terminals No. 10 (Black wire), No. 19 (Black wire), No. 39 (Black/Red wire), No. 45 (Black/Red wire), No. 96 (Black wire) and No. 104 (Black wire). If resistance readings are greater than 10 k/ohms, go to next step. If any resistance reading is less than 10 k/ohms, repair circuit in question for short to ground. Restore electrical connections and repeat QUICK TEST .
4. 12) Check MAF Sensor Harness
   
   Turn ignition off. Disconnect MAF sensor connector. Disconnect PCM. Measure resistance between PCM connector terminal No. 53 (Blue/Orange wire) and MAF sensor harness connector. Also measure resistance between PCM connector terminal No. 52 (White/Blue wire) and MAF sensor harness connector. If both resistance readings are less than 5 ohms, go to next step. If either resistance reading is greater than 5 ohms, repair open circuit in question. Restore electrical connections and repeat QUICK TEST .
5. 13) Check PCM
   
   Ensure PCM is connected. Connect NGS scan tool to fuse panel DLC. Start engine and let idle. Access MAF PID at idle and at 2000 RPM. If voltage is less than one volt, replace PCM. If voltage is one volt or greater, replace MAF sensor. Restore electrical connections and repeat QUICK TEST.
   NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.
6. 20) Check MAF Circuit For Short To Power
   
   Turn ignition off. Disconnect PCM and MAF sensor connectors. Measure resistance between MAF (White/Blue wire), MAF REF (Blue/Orange wire) and VPWR (Black/White wires) circuits. See Fig 1. If all resistance measurements are greater than 10 k/ohms, replace MAF sensor. If any resistance measurement is less than 10 k/ohms, repair circuit in question for short to power. Restore electrical connections and repeat QUICK TEST .
   NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step  20) to step  30). No test procedures have been omitted.
7. 30) MAF Sensor Performance Test
   
   Turn ignition off. Connect NGS scan tool to fuse panel DLC. Access MAF PID. Start and run engine to specified speeds. Refer to the MAF SENSOR PERFORMANCE  table. If MAF PID values do not agree with values in table, replace MAF sensor. If MAF PID values agree with table, fault may be intermittent. See TEST Z  or TROUBLE SHOOTING - NO CODES - VILLAGER article.