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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, go to QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed, go to next step.
  2. Verify 4X4L Position -  Verify vehicle is equipped with 4WD. Verify selector is in 4X2 or 4X4H position. If selector was in either position during QUICK TEST, go to next step. If selector was not in either position during QUICK TEST, select NEUTRAL position with shift lever. Select 4X2 or 4X4H position. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM.
  3. Check For Intermittent Circuit Fault -  With KOEO, cycle 4X4 Shift Control Switch to 4X2. Access and observe 4X4L PID while performing the following:
    • Grasp vehicle wiring harness starting at transfer case harness connector. Shake and bend a small section of harness, continuing to PCM.
    • Tap vehicle harness connector at transfer case.
    • Shake and bend a small section of harness between instrument cluster connector and PCM.
    If 4X4L PID changed on/off during harness and connector movement, isolate fault. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. Repair as necessary. After repair, go to step  7 . If 4X4L PID did not change on/off during harness and connector movement, go to next step.
  4. Check 4X4L Signal From Module -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure . With KOEO, measure voltage between breakout box terminals No. 68 (4X4L circuit) and 24 (PWR GND circuit) while cycling 4X4 Shift Control switch. If voltage cycles, replace faulty PCM. After repair, go to step  7 . If voltage does not cycle, go to next step.
    5. NOTE: Wire color for 4X4L circuit is not available from manufacturer.
    Fig 1: Identifying Electronic Shift Harness Connector Circuit
    G00155561Courtesy of MAZDA MOTORS CORP.
    Fig 2: Identifying Mechanical Shift Harness Connector Circuit
    G00155562Courtesy of MAZDA MOTORS CORP.
  5. Check Resistance Of 4X4L Wire -  Turn ignition off. Disconnect GEM module. Measure resistance of 4X4L circuit between breakout box terminals No. 68 (4X4L circuit) and 4X4 Shift Control switch harness connector. See Fig 1 or Fig 2 . If resistance reading is less than 5 ohms, go to next step. If resistance reading is 5 ohms or more, repair open circuit. After repair, go to step  7 .
  6. Check For Short To Power & Ground -  Reconnect GEM module. Measure resistance between breakout box terminals No. 68 (4X4L circuit) and 24/103 (VPWR circuit). Record reading. Measure resistance between breakout box terminals No. 68 (4X4L circuit) and 71/97 (VPWR circuit). Record reading. If each resistance reading is more than 10,000 ohms, see appropriate DIAGNOSIS article in TRANSFER CASES. If either resistance reading is 10,000 ohms or less, repair short circuit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to next step.
  7. Verify Trouble Shooting Of DTCs Completed -  Reconnect all electrical connectors. Using scan tool, clear DTC from PCM memory. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is present, replace faulty PCM and 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.
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