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Home >> Acura >> 2005 >> 1.7EL Automatic >> Repair and Diagnosis >> Engine Performance >> System >> EGR System >> DTC Troubleshooting >> DTC P1491: EGR Valve Insufficient Lift
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DTC P1491: EGR Valve Insufficient Lift

  1. Reset the ECM/PCM (see HOW TO RESET THE ECM/PCM ).
  2. Start the engine. Hold the engine at 3,000 RPM with no load (in Park or neutral) until the radiator fan comes on.
  3. Drive the vehicle under load for about 10 minutes. Try to keep the engine speed in the 1,700-2,500 RPM range.
  4. Check the Temporary DTC with the scan tool.

    Is Temporary DTC P1491 indicated? 

    1. YES  - Go to step 5.
    2. NO  - Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the EGR valve and at the ECM/PCM.
  5. Turn the ignition switch OFF.
  6. Disconnect the EGR valve 6P connector.
  7. Start the engine and let it idle.
  8. Measure voltage between the EGR valve 6P connector terminals No. 4 and No. 6.
    Fig 1: Measuring Voltage Between EGR Valve 6-Pin Connector Terminals No. 4 & No. 6
    G01954916

    Is there battery voltage? 

    1. YES  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ) If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Go to step 9.
  9. Turn the ignition switch OFF.
  10. Turn the ignition switch ON (II).
  11. Measure voltage between the EGR valve 6P connector terminals No. 2 and No. 3.
    Fig 2: Measuring Voltage Between EGR Valve 6-Pin Connector Terminals No. 2 & No. 3
    G01954917

    Is there about 5 V? 

    1. YES  - Go to step  13.
    2. NO  - Go to step 12.
  12. Measure voltage between ECM/PCM connector terminals A10 and A20.
    Fig 3: Measuring Voltage Between ECM/PCM Connector Terminals A10 & A20
    G01954918

    Is there about 5 V? 

    1. YES  - Repair open in the wire between the EGR valve and the ECM/PCM (A10, A20).
    2. NO  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
  13. Turn the ignition switch OFF.
  14. At the sensor side, measure resistance between the EGR valve 6P connector terminals No. 1 and No. 2.
    Fig 4: Measuring Resistance Between EGR Valve 6-Pin Connector Terminals No. 1 & No. 2
    G01954919

    Is there continuity or resistance of 100 k ohm or higher? 

    1. YES  - Replace the EGR valve.
    2. NO  - Go to step 15.
  15. Measure resistance between the EGR valve 6P connector terminals No. 1 and No. 3.
    Fig 5: Measuring Resistance Between EGR Valve 6-Pin Connector Terminals No. 1 & No. 3
    G01954920

    Is there 100 k ohm or higher? 

    1. YES  - Replace the EGR valve.
    2. NO  - Go to step 16.
  16. Reconnect the EGR valve connector.
  17. Turn the ignition switch ON (II).
  18. Measure voltage between ECM/PCM connector terminals A10 and A13.
    Fig 6: Measuring Voltage Between ECM/PCM Connector Terminals A10 & 13
    G01954921

    Is there about 1.2 V? 

    1. YES  - Go to step  21.
    2. NO  - Go to step 19.
  19. Turn the ignition switch OFF.
  20. Check for continuity between ECM/PCM connector terminal A13 and body ground.
    Fig 7: Checking Continuity Between ECM/PCM Connector Terminal A13 & Body Ground
    G01954922

    Is there continuity? 

    1. YES  - Repair short in the wire between the EGR valve and the ECM/PCM (A13).
    2. NO  - Repair open in the wire between the EGR valve and the ECM/PCM (A13).
  21. Turn the ignition switch OFF.
  22. Disconnect the EGR valve 6P connector.
  23. Connect the battery positive terminal to the EGR valve 6P connector terminal No. 4.
    Fig 8: Connecting Battery Positive Terminal To EGR Valve 6-Pin Connector Terminal No. 4
    G01954923
  24. Start the engine and let it idle, then connect the battery negative terminal to the EGR valve 6P connector terminal No. 6.

    Does the engine stall or run rough? 

    1. YES  - Go to step 25.
    2. NO  - Replace the EGR valve.
  25. Turn the ignition switch OFF.
  26. Disconnect ECM/PCM connector B (24P).
  27. Check for continuity between ECM/PCM connector terminal B14 and body ground.
    Fig 9: Checking Continuity Between ECM/PCM Connector Terminal B14 & Body Ground
    G01954924

    Is there continuity? 

    1. YES  - Repair short in the wire between the EGR valve and the ECM/PCM (B14).
    2. NO  - Go to step 28.
  28. Connect the EGR valve 6P connector terminal No. 4 and body ground with a jumper wire.
    Fig 10: Connecting EGR Valve 6-Pin Connector Terminal No. 4 & Body Ground
    G01954925
  29. Check for continuity between ECM/PCM connector terminal B14 and the body ground.
    Fig 11: Checking Continuity Between ECM/PCM Connector Terminal B14 & Body Ground
    G01954926

    Is there continuity? 

    1. YES  - Go to step 30.
    2. NO  - Repair open in the wire between the EGR valve and the ECM/PCM (B14).
  30. Disconnect the jumper wire from the EGR valve 6P connector.
  31. Check for continuity between the EGR valve 6P connector terminal No. 6 and body ground.
    Fig 12: Checking Continuity Between EGR Valve 6-Pin Connector Terminal No. 6 & Body Ground
    G01954927

    Is there continuity? 

    1. YES  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Repair open in the wire between the EGR valve and G101.
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