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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 P0400: 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 the scan tool Clear DTC Information function. Start the engine. Using the scan tool, gradually command the EGR valve OPEN to 100 percent. Does the engine run rough or stall? If yes, go to step  10 . If no, go to next step.
  5. Start the engine. Backprobe the EGR control circuit 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 the test light. Observe the test light on each circuit while commanding the EGR valve OPEN to 5% with the scan tool. The test light should illuminate and then turn OFF when the EGR valve is commanded OPEN. Does the 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 the test light. Observe the test light on each circuit while commanding the EGR valve OPEN to 5% with the scan tool. The test light should illuminate when the EGR valve is commanded OPEN. Does the EGR valve pass both tests? If yes, go to step  8 . If no, go to next step.
  7. Turn OFF the ignition. Disconnect the EGR valve electrical connector. Use a Digital Multimeter (DMM) to measure the following EGR valve coil windings for the specified value of resistance of 20-24 ohms at 68°F (20°C). Check 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. Check for any condition that can affect accuracy of MAP sensor, such as a malfunctioning or incorrectly calibrated MAP sensor, faulty manifold vacuum supply to sensor or an engine performance concern that can affect engine manifold vacuum readings. Repair as necessary. Was a repair necessary? If yes, go to step  19 . If no, go to next step.
  11. Fault is not present. Are there any DTCs stored that have not been diagnosed? If yes, see 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. Check EGR valve for sticking open or leaking EGR valve and gasket Repair or replace as necessary. After repairs, go to step  19 .
  14. Inspect the 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 the EGR coil control circuits between the EGR valve and the 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 replacing EGR valve, 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 ignition off. Clear DTCs by removing DOME fuse for 30 seconds. Reinstall fuse and reset radio clock time. Start engine and operate vehicle within the conditions for running the DTC or until this DTC diagnostic test has run. Does the DTC run and pass? If yes, go to next step. If no, go to step  2 .
  20. Using scan tool, observe stored information and 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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