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Home >> Mazda >> 1999 >> B2500 SX, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Engine Controls - Self-Diagnostics - EEC-V - 6.8L (99S E Series & 99S F350 To F550)) >> System Tests >> Test Dc: Mass Airflow (MAF) Sensor >> Diagnostic Aids

Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 26 other vehicles, including the 1999 Mercury Tracer, 1999 Mercury Sable, 1999 Mercury Mystique, 1999 Mercury Mountaineer, and 1999 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

Perform this test when directed by QUICK TEST. This test is intended to diagnose the following:

To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem:

  1. 1) KOER DTC P1101: Check MAF Sensor Continuous Memory DTCs

    DTC P1101, retrieved during KOER ON-DEMAND SELF-TEST, indicates MAF signal was not 0.34-1.96 volts during self-test. Drive vehicle for 6-10 minutes and repeat KOEO ON-DEMAND SELF-TEST  and CONTINUOUS MEMORY SELF-TEST . If any Continuous Memory DTCs are present with KOER P1101, proceed as follows:
    • Continuous Memory DTC P0102, go to next step.
    • Continuous Memory DTC P0103, go to step  20).
    • All other Continuous Memory DTCs, service DTCs as necessary.

    If no Continuous Memory DTCs are present with KOER P1101, turn ignition off and go to step  3).

  2. 2) DTC P0102: Low MAF Sensor Signal To PCM

    Check for broken or loose air outlet tube clamps at throttle body and air cleaner assembly. Check for holes and cracks in air outlet tube. Check for worn gaskets between MAF sensor and air cleaner. Repair as necessary. If no problems are detected, start engine and allow it to idle. Check for DTCs. If KOER DTC P0505 is present, go to  TEST KE, step 2). On A/T models, if engine stalls or cannot maintain idle speed, go to step  7). If KOER DTC P0505 is not present and engine idles okay, raise engine speed to 1500 RPM for 5 seconds, then return to idle. Using scan tool, select MAF V PID from PID/DATA monitor menu. If MAF V PID voltage is less than .23 volt, turn ignition off and go to step  4). If MAF V PID voltage is .23 volt or more, go to next step.
    3. NOTE: DTC P1101 may be caused by low battery or by use of a garage exhaust ventilation system. Ensure vehicle is vented to outside atmosphere before repeating QUICK TEST .

  3. 3) KOEO/KOER DTC P1101: MAF Output Voltage
    Ensure MAF sensor is connected properly. If MAF sensor is not connected properly, repair as necessary and retest. Start engine and allow it to idle. Using scan tool, select MAF V PID from PID/DATA monitor menu. If MAF V PID voltage is .46-2.44 volts, no problem is indicated at this time. Turn ignition off and go to TEST Z . If MAF V PID voltage is not .46-2.44 volts, turn ignition off and go to next step.

  4. 4) Check VPWR Voltage To MAF Sensor

    Disconnect MAF sensor. Turn ignition on. Measure voltage between ground and VPWR terminal at MAF sensor wiring harness connector. If voltage is more than 10.5 volts, go to next step. If voltage is not more than 10.5 volts, locate and repair open in VPWR circuit.

  5. 5) Check PWR GND Circuit

    Measure voltage between positive battery terminal and PWR GND terminal at MAF sensor wiring harness connector. If voltage is more than 10 volts, turn ignition off and go to next step. If voltage is not more than 10 volts, locate and repair open in PWR GND circuit.

  6. 6) Check Resistance Of VPWR Circuit

    Turn ignition off. Leave MAF sensor disconnected. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between VPWR terminal at MAF sensor wiring harness connector and PCM connector pin No. 71. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in VPWR circuit. Reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES.

  7. 7) Check MAF Circuit For Short To Ground Or MAF RTN Circuit

    Disconnect scan tool Data Link Connector (DLC). Measure resistance between PCM connector pin No. 88 (MAF SIG) and pins No. 36 (MAF RTN), 51, 77 and 103 (PWR GND). If all resistance readings are more than 10,000 ohms, go to next step. If any resistance is 10,000 ohms or less, repair short to ground and reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES.

  8. 8) Check MAF RTN Circuit For Short To PWR GND Circuit

    Measure resistance between PCM connector pin No. 36 (MAF RTN) and pins No. 51, 77 and 103 (PWR GND). If all resistance readings are more than 10,000 ohms, reconnect scan tool and go to next step. If any resistance is 10,000 ohms or less, repair short to ground.

  9. 9) Check MAF Circuit Voltage Cycling Integrity

    Reconnect PCM connector. Turn ignition on. Using scan tool, select MAF V PID from PID/DATA monitor menu. Note reading. Connect a jumper wire between MAF RTN and PWR GND terminals at MAF sensor wiring harness connector. Connect another jumper wire between VPWR and MAF terminals at MAF sensor wiring harness connector. Compare voltage readings. If voltage changes from .23 volt to more than 4.5 volts, replace MAF sensor. Reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES. If voltage does not change from .23 volt to more than 4.5 volts, proceed as follows:
    • If DTC P1101 is present without DTC P0102, go to step  11).
    • If DTC is present, go to next step.

  10. 10) Check Resistance Of MAF Signal Circuit

    Disconnect PCM connector. Measure resistance between MAF terminal at MAF sensor wiring harness connector and PCM connector pin No. 88 (MAF). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in MAF circuit and reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES.

  11. 11) Check PWR GND Circuit Resistance

    Ensure ignition is off. Ensure PCM is disconnected. Disconnect scan tool Data Link Connector (DLC). Measure resistance between PWR GND terminal at MAF sensor wiring harness connector and negative battery terminal. If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or more, repair open in PWR GND circuit and reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES.

  12. 12) Check MAF RTN Circuit Resistance

    Measure resistance between MAF RTN terminal at MAF sensor wiring harness connector and PCM connector pin No. 36 (MAF RTN). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in MAF RTN circuit and reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 16). No test procedures have been omitted.

  13. 16) DTC P1100: Check MAF Circuit For Intermittent Voltage To PCM

    Start engine and allow it to idle. If idle is not stable, go to TROUBLE SHOOTING - NO CODES - EEC-V article and diagnose by symptom. Raise engine speed to 1500 RPM for 5 seconds, then return to idle. Using scan tool, select MAF V PID from PID/DATA monitor menu. While observing PID, tap on MAF sensor to simulate road shock. Wiggle sensor connector. If any change in PID voltage occurs, inspect MAF sensor connector. Repair connector as necessary. If connector is okay, replace MAF sensor. Reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES. If no change in PID voltage reading occurs, go to next step.

  14. 17) DTC P1101: Check MAF Circuit For Intermittent Open Or Short

    Turn ignition on. Using scan tool, select MAF V PID from PID/DATA monitor menu. While observing PID, wiggle small sections of wiring harness starting at MAF sensor working toward PCM. If any change in PID voltage occurs, repair wiring harness as necessary. Reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES. If no change in PID voltage reading occurs, no problem is indicated at this time. Turn ignition off and go to TEST Z .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 17) to step 20). No test procedures have been omitted.

  15. 20) DTC P0103: Check MAF High Input Signal To PCM

    DTC P0103 indicates MAF signal was high sometime during normal engine operation. Possible causes for this fault are:
    • Restricted MAF sensor screen.
    • MAF SIG circuit shorted to VPWR.
    • Faulty MAF sensor or connector.
    • Faulty PCM.

    Ensure air induction system is okay. Repair if necessary. Start engine and allow to idle. If engine does not idle smoothly, repair cause of rough idle condition before continuing. If KOER DTC P0505 is present, go to  TEST KE, step 2). On Ranger 2.5L A/T, if engine stalls or cannot maintain idle, replace PCM. On all models, if engine idles smoothly, raise engine speed to 1500 RPM for 5 seconds then return to idle. Using scan tool, select MAF V PID from PID/DATA monitor menu. PID value should be more than 3.90 volts. Turn ignition off. Disconnect MAF sensor connector. Connect a jumper wire between PWR GND and MAF RTN terminals at MAF sensor wiring harness connector. Start engine and allow to idle. Using scan tool, select MAF V PID from PID/DATA monitor menu. If PID value does not change to less than .23 volt, turn ignition off, disconnect jumper wire and go to next step. If PID value changes to less than .23 volt, turn ignition off. Remove jumper wire and replace MAF sensor. Reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES.

  16. 21) Check MAF Circuit For Short To Power

    Leave ignition off and MAF sensor disconnected. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Turn ignition on. Measure voltage between PCM connector pins No. 88 (MAF) and No. 103 (PWR GND). If voltage is less than one volt, go to next step. If voltage is one volt or more, repair MAF circuit short to power.

  17. 22) Check MAF Circuit For Short To VREF

    Measure resistance between PCM connector pins No. 88 (MAF) and No. 90 (VPWR). If resistance is more than 10,000 ohms, replace PCM. If resistance is 10,000 ohms or less, repair short between MAF and VREF circuit and reset Keep-Alive Memory (KAM). See RESETTING KEEP-ALIVE MEMORY (KAM)  under CLEARING CODES.
Fig 1: Identifying MAF Sensor Extension Connector & Circuits (Continental)
G99D02595Courtesy of FORD MOTOR CO.
Fig 2: Identifying MAF Sensor Wiring Harness Connector & Circuits (Contour 2.0L & Mystique 2.0L)
G99H02597Courtesy of FORD MOTOR CO.
Fig 3: Identifying MAF Sensor Wiring Harness Connector & Circuits (Econoline 4.2L, Escort, Explorer, Mountaineer, Tracer & Windstar)
G99E02082Courtesy of FORD MOTOR CO.
Fig 4: Identifying MAF Sensor Extension Connector & Circuits (Econoline 4.6L & 5.4L, Escort, Expedition, Navigator, Pickup 4.2L, 4.6L & 5.4L, Tracer & Windstar)
G99B02599Courtesy of FORD MOTOR CO.
Fig 5: Identifying MAF Sensor Extension Connector & Circuits (Mustang)
G99G02083Courtesy of FORD MOTOR CO.
Fig 6: Identifying MAF Sensor Extension Connector & Circuits (Ranger)
G99I02084Courtesy of FORD MOTOR CO.
Fig 7: Identifying MAF Sensor Wiring Harness Connector & Circuits (All Other Models)
G99B02085Courtesy of FORD MOTOR CO.
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