LEMON Manuals: Even more car manuals for everyone
Home >> Mazda >> 2007 >> B4000 SE, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 70 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0505, DTC P1504 Or DTC P1507 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Mazda B4000, 2003 Mazda B3000, and 2003 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
  1. If QUICK TEST was not performed, repair open in VPWR circuit (Red wire) between PCM 104-pin harness connector terminal No. 71 and IAC valve 2-pin harness connector. See Fig 1 . Go to step  12 . If QUICK TEST was performed, go to next step.
    Fig 1: Identifying IAC Valve Harness Connector Circuits
    G00155549Courtesy of MAZDA MOTORS CORP.
    2. NOTE: If DTC P0402 or P0403 was output during Self-Test, diagnose P0402 or P0403 first before continuing with this procedure.
  2. DTC P0505, P1504, P1507 Or Starts Only At Part Throttle: Check VPWR To IAC Valve Assembly -  Disconnect IAC valve 2-pin harness connector. With KOEO, measure voltage between VPWR circuit (Red wire) at IAC valve harness connector and ground. See Fig 1 . Observe voltage. Turn ignition off. If voltage reading was more than 10.5 volts, go to next step. If voltage reading was 10.5 volts or less, repair open VPWR circuit (Red wire) between PCM 104-pin harness connector terminal No. 71 and IAC valve harness connector. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  12 .
    3. NOTE: During next test step, place DVOM positive lead on VPWR terminal and negative lead on IAC terminal.
  3. Check IAC Valve Resistance -  Measure resistance between VPWR terminal and IAC terminal of IAC valve. See Fig 1 . If resistance reading is 6-13 ohms, go to next step. If resistance reading is not 6-13 ohms, replace faulty IAC valve assembly. After repair, go to step  12 .
  4. Check IAC Valve Assembly For An Internal Short To IAC Case -  Measure resistance between IAC valve circuit terminal and IAC valve case. See Fig 1 . If resistance reading is more than 10,000 ohms:
    • For DTC P1504, go to step  7 .
    • For all others, go to next step.
    If resistance reading is 10,000 ohms or less, replace faulty IAC valve. After repair, go to step  12 .
  5. Check Air Inlet For Plugging -  Inspect air intake system for blockage or other damage. Inspect air cleaner for excessive dirt. If air intake system is okay, restore air intake system. Go to next step. If air intake system is not okay, repair as necessary. After repair, go to step  12 .
  6. Check For Vacuum Leaks -  With KOER, listen for vacuum leaks with engine idling. Inspect air intake system from Mass Airflow (MAF) sensor to intake manifold for leaks. Inspect for the following conditions:
    • Air intake tube cracked or punctured.
    • Air intake tube loose at air cleaner housing or throttle body.
    • EGR valve gasket.
    • IAC valve assembly or gasket seal.
    • Vacuum supply connector and hose.
    • PCV connectors and hose.
    Turn ignition off. If any leaks are detected, repair as necessary. After repair, go to step  12 . If no leaks are found, go to next step.
  7. Check IAC Circuit Resistance -  Disconnect PCM 104-pin harness connector and IAC valve harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure . Measure resistance of IAC circuit (White/Light Blue wire) between breakout box terminal No. 83 and IAC valve harness connector. If resistance reading is less than 5 ohms, go to next step. If resistance reading is 5 ohms or more, repair open circuit in White/Blue wire between PCM 104-pin harness connector terminal No. 83 and IAC valve harness connector. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  12 .
  8. Check IAC Circuit For Short To PWR -  With KOEO, measure voltage between breakout box terminal No. 83 and chassis ground. Observe voltage. Turn ignition off. If voltage reading was less than one volt, go to next step. If voltage reading was one volt or more, repair short circuit. After repair, go to step  12 .
  9. Check IAC Circuit For Short To Ground -  Disconnect scan tool from DLC. Measure resistance between breakout box terminals No. 83 (IAC circuit) and No. 103 (PWR GND circuit). If resistance reading is more than 10,000 ohms, go to next step. If resistance reading is 10,000 ohms or less, repair short circuit. After repair, go to step  12 .
    10. NOTE: During next step, if engine is stalling, place a shim under the hard stop screw to maintain idle. During test procedure, if closed throttle RPM is significantly higher than normal, go to step  11 .
  10. Check IAC Signal From PCM -  Remove breakout box. Reconnect PCM and IAC valve harness connectors. Start engine. Using scan tool, select DIAGNOSTIC DATA LINK. Select PCM. Select PID MONITOR AND RECORD. Access IAC and RPM PIDs. With engine at normal operating temperature, all accessories off, and throttle closed, IAC duty cycle must be about 22-45 percent. Observe IAC duty cycle. Slowly increase engine speed to 3000 RPM and return to closed throttle. Observe IAC duty cycle. If IAC duty cycle is within specification at closed throttle and duty cycle responds to RPM change:
    • For Continuous Memory DTCs P1504 and P1507, go to next step.
    • For all others, turn ignition off. Inspect throttle body for damage. Repair as necessary. After repair, go to step  12 . If throttle body is okay, replace faulty IAC valve. After repair, go to step  12 .

    If IAC duty cycle is not within specification at closed throttle and/or duty cycle does not respond to RPM change:

    • For DTC P1507, replace faulty IAC valve. After repair, go to step  12 .
    • For all others, replace faulty PCM. After repair, go to step  12 .

  11. Check IAC System For Intermittent Open Or Short -  Using scan tool, select DIAGNOSTIC DATA LINK. Select PCM. Select PID MONITOR AND RECORD. Access IAC and RPM PIDs. Observe PIDs for an indication of a fault while performing the following at idle:
    • Lightly tap on IAC valve and wiggle harness connector to simulate road shock.
    • Grasp vehicle harness closest to IAC valve. Shake and bend a small section of wiring harness from IAC valve to dash panel, and from dash panel to PCM connector.

    If IAC and RPM PIDs suddenly change in value indicating a fault, isolate fault and repair as necessary. After repair, go to next step. If IAC and RPM PIDs do not suddenly change in value:

    • For idle quality, starting or stalling problems, replace faulty IAC valve. After repair, go to next step.
    • For all others, fault is not present at this time. See INTERMITTENT  testing under SYSTEM TESTS.

  12. Verify Trouble Shooting Of DTCs Completed -  Reconnect all electrical connectors. Clear DTCs from PCM memory using scan tool. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is present, replace faulty PCM. Repeat QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTC is present, trouble shooting is complete.
scientia non olet · About LEMON Manuals