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Home >> Chevrolet >> 2002 >> Tracker 2D Utility, RWD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 2.0L >> Diagnostic Tests >> DTC P0401: EGR System >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Is DTC P0403 also set? If yes, go to DTC P0403: EGR SOLENOID CONTROL CIRCUIT  . If no, go to next step.
  3. Start the engine. Run the engine at a normal operating temperature. Does the engine run rough, or is the idle unstable? If yes, go to step  12 . If no, go to next step.
  4. Install a scan tool. Perform scan tool Clear DTC Information function. Start engine. Using scan tool, gradually command EGR valve OPEN to 100 percent. Does engine run rough or stall? If yes, go to step  10 . If no, go to next step.
  5. Start engine. Backprobe EGR control circuits terminals No. 1 and 4 with a test light connected to ground. The test light should illuminate on both circuits. Continue to backprobe both EGR control circuits with test light. Observe test light on each circuit while commanding the EGR valve OPEN to 5% with scan tool. The test light should illuminate and then turn OFF when EGR valve is commanded OPEN. Does EGR valve pass both tests? If yes, go to next step. If no, go to step  7 .
  6. Start the engine. Backprobe the EGR control circuit terminals No. 3 and 6 with a test light connected to ground. The test light should NOT illuminate on either circuit. Continue to backprobe both EGR control circuits with test light. Observe test light on each circuit while commanding the EGR valve OPEN to 5% with scan tool. The test light should illuminate when EGR valve is commanded OPEN. Does EGR valve pass both tests? If yes, go to step  8 . If no, go to next step.
  7. Turn OFF ignition. Disconnect EGR valve electrical connector. Use a Digital Multimeter (DMM) to measure the following EGR valve coil windings for the specified value of 20-24 ohms at 68°F (20°C). Check resistance between terminals No. 1 and 2, between terminals No. 2 and 3, between terminals No. 5 and 6, and between terminals No. 4 and 5. Measure resistance between terminal No. 2 and EGR valve assembly, and between terminal No. 5 and EGR assembly. Resistance should be infinite. Does EGR valve pass all resistance tests? If yes, go to step  9 . If no, go to step  17 .
  8. Remove EGR valve. Inspect all the EGR passages for any obstruction or blockage. Inspect the EGR valve for physical damage or carbon deposits. Repair as necessary. Was a repair necessary? If yes, go to step  19 . If no, go to step  17 .
  9. Disconnect EGR valve electrical connector. Turn ON ignition, leaving engine OFF. Connect a test light between harness side of terminal No. 2 and ground. Connect a test light between harness side of terminal No. 5 and ground. Did test light illuminate for both circuits? If yes, go to step  16 . If no, go to step  15 .
  10. Inspect the vehicle for any condition that can affect the accuracy of the Manifold Absolute Pressure (MAP) sensor: A malfunctioning or incorrectly calibrated MAP sensor, a faulty manifold vacuum supply to the MAP sensor, or an engine performance concern that can affect the engine manifold vacuum readings. Repair as necessary. Was a repair necessary? If yes, go to step  19 . If no, go to next step.
  11. The fault is not present. Are there any DTCs stored that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, see DIAGNOSTIC AIDS  .
  12. With the engine running, disconnect the EGR valve electrical connector. Does the engine performance improve when the EGR valve is disconnected? If yes, go to step  14 . If no, go to next step.
  13. Remove EGR valve. Inspect EGR valve for sticking open. Inspect EGR valve and gasket for leaks. Repair or replace as necessary. After repairs, go to step  19 .
  14. Inspect EGR coil control circuits for a short to ground. Repair as necessary. Was a repair necessary? If yes, go to step  19 . If no, go to step  18 .
  15. Repair ignition positive voltage supply to EGR valve. After repairs, go to step  19 .
  16. Inspect for an open or a short in EGR coil control circuits between EGR valve and PCM. Repair as necessary. Was a repair necessary? If yes, go to step  19 . If no, go to step  18 .
  17. Replace EGR valve. After repairs, go to step  19 .
  18. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  19. Turn OFF ignition. Remove DOME fuse for 30 seconds. Install DOME fuse. Reset radio clock time. Start engine. Operate vehicle within Conditions for Running the DTC or until DTC P0401 diagnostic test has run. See CONDITIONS FOR RUNNING DTC  . Does the DTC run and pass? If yes, go to next step. If no, go to step  2 .
  20. With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, system is okay.
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