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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 P0505: Idle Air Control (IAC) Valve, System Malfunction >> 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. Using scan tool, check for other DTCs. If any other DTCs are present, go to appropriate test first. If no other DTC is present, go to next step.
  3. Start engine. Using scan tool switch IACV PID to 100 percent. If engine speed increases, go to next step If engine speed does not increase, replace IAC valve and go to step  8 .
  4. With engine running, turn A/C and blower motor on. Ensure A/C compressor clutch is engaged. Turn blower motor off. If A/C compressor clutch disengages, go to next step. If A/C compressor clutch does not disengage, A/C compressor runs continuously. See HVAC SYSTEM - 626 article.
  5. Using scan tool, switch ALTF PID to zero percent. If engine speed increases, go to next step. If engine speed does not increase, repair short to power in appropriate circuit. See WIRING DIAGRAMS article. Go to step  8 .
  6. Check air cleaner for plugging. Replace as necessary. Check throttle body for plugging. Clean or replace as necessary and go to step  8 . If air cleaner and throttle body are okay, go to next step.
  7. Check engine compression. Ensure engine compression is even and within specification. Repair as necessary and go to next step. If no faults can be found, go to next step.
  8. Reconnect all connections. Start engine. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Check for DTCs during KOER self-test. If DTC P0505 is present, replace PCM and go to next step. See REMOVAL, OVERHAUL & INSTALLATION article. On vehicles equipped with immobilizer system, reprogram ignition key identification numbers. See COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. If DTC P0505 is not present, go to next step.
  9. Perform DTC confirmation procedure. See DTC CONFIRMATION PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to appropriate test.
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