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Home >> Mazda >> 2002 >> Protege ES, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0506: Idle Control System, Rpm Less Than Expected >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

  1. Turn ignition off. Connect scan tool to DLC-2. Turn ignition on, engine off. Monitor for FREEZE FRAME DATA and ensure data has been recorded. Check service bulletins for repair information related to this DTC. If repair information is not available, go to next step. If repair information is available, perform diagnosis and repair as necessary. After repair, go to step  10.
  2. Turn ignition switch off and then on, engine off. Using scan tool, check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If any other DTCs are present, go to appropriate test and repair first. If no other DTCs are present, go to next step.
  3. Perform IAC valve inspection. See IDLE AIR CONTROL VALVE under IDLE CONTROL in SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE, PROTEGE5 & 626 article. If IAC valve is okay, go to next step. If IAC valve is faulty, replace IAC valve. After repair, go to step  10.
  4. Turn blower motor switch off. Ensure A/C is off. Check A/C compressor. If A/C compressor is not operating, go to next step. If compressor is operating, diagnose and repair A/C system. See A/C IS ALWAYS ON OR COMPRESSOR RUNS CONTINUOUSLY under SYMPTOM DIAGNOSIS in TROUBLE SHOOTING - NO CODES article. After repair, go to step  10.
  5. Turn ignition switch off. Disconnect generator harness connector. Turn ignition switch on. Measure voltage between ground and Light Green/White wire at generator harness connector. See WIRING DIAGRAMS article. If zero voltage is present, go to next step. If voltage is not as specified, repair short to power in Light Green/White wire (generator control circuit) between generator connector and PCM 104-pin harness connector terminal No. 53. After repair, go to step  10.
  6. Perform purge solenoid valve test. See FUEL EVAPORATIVE SYSTEM - EXCEPT MPV in SYSTEM & COMPONENT TESTING - MIATA, MILLENIA, MPV, PROTEGE, PROTEGE5 & 626 article. If purge solenoid valve is okay, go to next step. If valve is not okay, replace purge solenoid valve. After repair, go to step  10.
  7. With engine running, remove air cleaner. If engine speed does not increase, go to next step. If engine speed increases, replace air filter. After repair, go to step  10.
  8. Check throttle body passage for plugging. If throttle body passage is clogged, clean or replace throttle body as necessary. After repair, go to step  10. If throttle body is okay, go to next step.
  9. Check engine compression. Engine compression should be a minimum of 119 psi (8.4 kg/cm2 ) at 300 RPM with a maximum variation of 28 psi (2 kg/cm2 ). If compression is as specified, go to next step. If compression is not as specified, repair as necessary. After repair, go to next step.
  10. Reconnect all connectors. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine. Depress brake pedal for 14.1 seconds or more. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P0506 is present, replace PCM and go to next step. If DTC P0506 is not present, go to next step.
  11. Cycle ignition switch from off to on. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If no other DTCs are present, testing is complete. If any other DTC is present, go to applicable test and repair.
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