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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 26 (Engine Controls - Self-Diagnostics - 2.0L) >> Diagnostic Tests >> DTC P0506: Idle Control System, Rpm Less Than Expected >> Diagnosis & Repair Procedure

Diagnosis & Repair Procedure

WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ensure FREEZE FRAME DATA has been recorded. Check for related service bulletins. Repair as necessary and go to next step.
  2. Turn ignition off and then on, with 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. Start engine. Disconnect IAC valve electrical connector. Observe engine RPM. If engine RPM decreased, go to next step. If engine RPM did not decrease, replace faulty IAC valve. Go to step  9 .
  4. Turn blower motor switch off. Observe A/C clutch operation. If A/C compressor clutch is not operating, go to next step. If A/C compressor clutch is operating, repair A/C system as necessary. See A/C IS ALWAYS ON OR COMPRESSOR RUNS CONTINUOUSLY under SYMPTOM DIAGNOSIS in TROUBLE SHOOTING - NO CODES article. After repair, go to step  9 .
  5. With engine idling, turn on some electrical accessories. Observe engine RPM. If engine RPM increases, go to next step. If engine RPM does not increase, repair short to power circuit in generator control circuit. See WIRING DIAGRAMS article. After repair, go to step  9 .
  6. With engine idling, remove air cleaner element. Observe engine RPM. If engine RPM does not increase, go to next step. If engine RPM increases, replace dirty air cleaner element. After repair, go to step  9 .
  7. Turn engine off. Inspect throttle body passage for contamination. If contamination is present, clean or replace throttle body assembly as necessary. After repair, go to step  9 . If contamination is not present, go to next step.
  8. 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 okay, go to next step. If compression is not okay, repair as necessary. After repair, go to next step.
  9. 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.
  10. 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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