LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 100 (Engine Control System Self-Diagnostics - 3.8L) >> Diagnostic Tests >> DTC P0412: Secondary Air Injection Solenoid Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 Pontiac Grand Prix, 2002 Pontiac Bonneville, 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, and 2002 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
  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. Turn on the ignition, with the engine off. Command the secondary Air Injection (AIR) solenoid on and off with a scan tool. Does the AIR solenoid turn on and off with each command? If yes, see DIAGNOSTIC AIDS . If no, go to next step.
  3. Turn off the ignition. Disconnect the solenoid. Turn on the ignition, with the engine off. Probe the ignition 1 voltage circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  10.
  4. Connect a test lamp between the control circuit and the ignition 1 voltage circuit of the solenoid. Command the AIR solenoid on and off with a scan tool. Does the test lamp turn on and off with each command? If yes, go to step  8. If no, go to next step.
  5. Does the test lamp remain illuminated with each command? If yes, go to step  7. If no, go to next step.
  6. Test the control circuit of the solenoid for the following conditions:
    • A short to voltage.
    • High resistance.
    • An open.

    Repair as necessary. Did you find and correct the condition? If yes, go to step  13. If no, go to step  9.

  7. Test the control circuit of the solenoid for a short to ground. Did you find and correct the condition? If yes, go to step  13. If no, go to step  9.
  8. Inspect for poor connections at the AIR solenoid. Did you find and correct the condition? If yes, go to step  13. If no, go to step  11.
  9. Inspect for poor connections at PCM. Did you find and correct the condition? If yes, go to step  13. If no, go to step  12.
    10. NOTE: Check fuses. If blown, replace.
  10. Test for a short to ground or open in the coil feed circuit. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  11. Replace AIR solenoid. After replacing solenoid, go to step  13.
  12. Replace PCM. Program replacement PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  13. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within Conditions for Running DTC. Does DTC run and pass? If yes, go to next step. If no, go to step  2.
  14. Using scan tool, observe stored information. Does scan tool displays any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
scientia non olet · About LEMON Manuals