Diagnostic Aids

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

• MAF sensor.
• Wiring harness circuits (VPWR, PWR GND, MAF SIG and MAF RTN).
• Powertrain Control Module (PCM).

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

• Air cleaner element.
• Inlet air duct.
• Throttle body.

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 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 step 6).
   • 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, go to next step.

   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  .
2. 2) KOEO/KOER DTC P1101: MAF Output Voltage
   
   DTC P1101, retrieved during KOEO or KOER ON-DEMAND SELF-TEST, indicates voltage exceeded .2-volt test range. Possible causes for this fault are:
   • Air leak before or after MAF sensor.
   • Faulty or contaminated MAF sensor.
   • Faulty MAF sensor wiring harness connector.
   • Open PWR GND or MAF RTN circuit.
   • Faulty PCM.

   Turn ignition off. Ensure MAF sensor is connected properly. If MAF sensor is not connected properly, repair as necessary and retest. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box (014-00950) and connect PCM to breakout box. Turn ignition on. Measure voltage between test pin No. 88 (MAF SIG) and test pins No. 103 (PWR GND) at breakout box. If voltage is more than .2 volt, go to step 12). If voltage is .2 volt or less, go to step 8).

3. 3) Continuous Memory DTC P1100: Check MAF Circuit Intermittent Voltage Input
   
   DTC P1100, retrieved from continuous memory indicates voltage went out of range (.39-3.90 volts) sometime during previous 40 warm-up cycles. Possible causes for this fault are:
   • Faulty MAF sensor.
   • Faulty MAF sensor wiring harness circuit or connector.

   Start engine and allow to idle. If engine does not idle smoothly, repair cause of rough idle condition before continuing. Raise engine speed to 1500 RPM for 5 seconds, and return to idle. Using scan tool, select MAF PID from PID/DATA monitor menu. While observing PID, tap on sensor to simulate road shock. Wiggle sensor connector. If MAF PID voltage stays within .39-3.90 volts range, go to next step. If MAF PID voltage does not stay within .39-3.90 volts range, check MAF sensor connector for loose, damaged or corroded terminals. Repair as necessary. If connector is okay, replace MAF sensor.

4. 4) Check MAF Sensor Circuit Integrity
   
   Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Install Breakout Box (014-00950) and connect PCM to breakout box. Turn ignition on. Connect voltmeter between test pin No. 36 (MAF RTN) and No. 88 (MAF SIG). While observing voltmeter, wiggle and bend wiring harness between sensor and dash panel. Wiggle and bend wiring harness between dash panel and PCM. If voltage reading goes out of normal range (.39-3.90 volts), isolate fault and repair as necessary. Reset Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes. If voltage does not go out of normal range, fault cannot be duplicated or identified at this time. Go to CIRCUIT TEST Z  .
   NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 6). No test procedures have been omitted.
5. 6) Continuous Memory & KOER DTC P0102: Check MAF Low Input Signal To PCM
   
   DTC P0102 indicates MAF signal was less than .39 volt sometime during normal engine operation. Possible causes for this fault are:
   • Open or closed MAF circuit.
   • Open circuit (MAF, MAF RTN, PWR GND, or VPWR).
   • MAF circuit shorted to ground.
   • Air leak before or after MAF sensor.
   • Faulty MAF sensor or connector.
   • Faulty TP system.
   • 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 CIRCUIT TEST KE  , step 2). On A/T models, if vehicle cannot maintain an idle and engine stalls, go to step 9). 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. If PID value is less than .39 volt, go to next step. If PID value is .6-1.0 volt, go to step 15). For all other PID values, go to step 2).

6. 7) Check VPWR Circuit Voltage
   
   Turn ignition off. Disconnect MAF sensor. Turn ignition on. Measure voltage between VPWR terminal of MAF sensor wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in VPWR circuit. Reset Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes.
7. 8) 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. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between VPWR terminal of MAF sensor wiring harness connector and test pin No. 71 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in VPWR circuit.
8. 9) Check MAF Circuit For Short To Ground Or MAF RTN Circuit
   
   Disconnect scan tool Data Link Connector (DLC). Measure resistance between test pin No. 88 (MAF SIG) and test pins No. 36 (MAF RTN), 51 and 103 (PWR GND) at breakout box. If all resistance readings are more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground and reset Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes.
9. 10) Check MAF RTN Circuit For Short To PWR GND Circuit
   
   Measure resistance between test pin No. 36 (MAF RTN) and test pins No. 51 and 103 (PWR GND) at breakout box. If both resistance readings are more than 10,000 ohms, reconnect scan tool and go to next step. If resistance is 10,000 ohms or less, repair short to ground and reset Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes.
10. 11) Check Resistance Of MAF Signal Circuit
    
    Measure resistance between MAF terminal at MAF sensor wiring harness connector and test pin No. 88 (MAF) at breakout box. 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). To clear KAM, disconnect negative battery terminal for at least 5 minutes.
11. 12) Check PWR GND Circuit To MAF Sensor
    
    Connect PCM to breakout box. Turn ignition on. Measure voltage between VPWR and PWR GND terminals at MAF sensor wiring harness connector. If voltage is 10.5 volts or less, go to next step. If voltage is more than 10.5 volts, go to step 14).
12. 13) Check PWR GND Circuit Resistance
    
    Disconnect PCM from breakout box. 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). To clear KAM, disconnect negative battery terminal for at least 5 minutes.
13. 14) Check MAF RTN Circuit Resistance
    
    Measure resistance between MAF RTN terminal at MAF sensor wiring harness connector and test pin No. 36 (MAF RTN) at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in MAF RTN and reset Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes.
14. 15) Check MAF Circuit For Short To Ground In PCM
    
    Connect PCM to breakout box. Disconnect scan tool Data Link Connector (DLC). Measure resistance between test pin No. 88 (MAF) and test pins No. 36 (MAF RTN), 51 and 103 (PWR GND) at breakout box. If all resistance readings are more than 10,000 ohms, go to next step. If any resistance reading is 10,000 ohms or less, replace PCM.
15. 16) Check MAF RTN Circuit For Short To Ground
    
    Measure resistance between test pin No. 36 (MAF RTN) and test pins No. 51 and 103 (PWR GND) at breakout box. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, replace PCM.
16. 17) Check MAF Circuit Output
    
    Ensure ignition is off. Reconnect MAF sensor. Ensure PCM is connected to breakout box. Start engine and allow to idle. If engine does not idle smoothly, repair cause of rough idle condition before continuing. Measure voltage between test pin No. 88 (MAF) and negative battery terminal. If voltage is .34-1.96 volts, go to next step. If voltage is not .34-1.96 volts, replace MAF sensor and reset Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes.
17. 18) Measure Voltage Between MAF & MAF RTN Circuits
    
    With engine idling, measure voltage between test pin No. 36 (MAF RTN) and 88 (MAF) at breakout box. If voltage is .34-1.96 volts, go to next step. If voltage is not .34-1.96 volts, replace MAF sensor and reset Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes.
18. 19) Check MAF Circuit Output With Scan Tool
    
    Start engine and allow to idle. Using scan tool, select MAF V PID from PID/DATA monitor menu. If PID value is .34-1.96 volts, fault is intermittent and cannot be identified at this time. Go to CIRCUIT TEST Z  . If voltage is not .34-1.96 volts, replace PCM.
19. 20) DTC P0103: Check MAF High Input Signal To PCM
    
    DTC P0103 indicates MAF signal was more than 3.9 volts 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 CIRCUIT TEST KE  , step 2) 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 .39 volt, go to next step. If PID value changes to less than .39 volt, replace MAF sensor and reset Keep-Alive Memory (KAM). To clear KAM, disconnect negative battery terminal for at least 5 minutes.

20. 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. Install Breakout Box (014-00950), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 88 (MAF) and test pin No. 24 or 103 at breakout box. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair MAF circuit short to power.
21. 22) Check MAF Circuit For Short To VREF
    
    Turn ignition off. Measure resistance between test pin No. 88 (MAF) and test pin No. 90 (VPWR) at breakout box. 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). To clear KAM, disconnect negative battery terminal for at least 5 minutes.