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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 P1506: 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 on. Using scan tool, check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If any other DTCs are present, go to appropriate testing procedure. If no other DTC is present, go to next step.
  3. Start engine. Using scan tool, check IACV PID data. 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  7 .
  4. Turn A/C and fan off. If A/C compressor clutch is still engaged, check for A/C remaining on fault. See HVAC SYSTEM - 626 article. See If A/C compressor clutch is not engaged, go to next step.
  5. Using scan tool, activate ALTF PID to zero percent. If engine speed increases, go to next step. If engine speed does not increase, check for short to power in generator control circuit and go to step  7 . See GENERATORS & REGULATORS - EXCEPT PICKUP & TRIBUTE article in STARTING & CHARGING SYSTEMS.
  6. Remove air cleaner element. If engine speed increases, replace air cleaner element and go to next step. If engine speed does not increase, check throttle body passage for restrictions. If throttle body passage is clean, check engine compression. Ensure engine compression is even and within specification. Repair as necessary and go to next step. If engine compression is okay, go to next step.
  7. Reconnect all connections. Start engine. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Depress brake pedal for 14.1 or more seconds. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P1506 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 P1506 is not present, go to next step.
  8. 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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