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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:
    • For Continuous Memory DTC P1474, go to step  7 .
    • For all others, go to next step.
  2. Check VPWR Voltage To Fan Relay -  Disconnect FC relay. With KOEO, measure VPWR circuit (Red wire) voltage at FC relay 5-pin harness connector. See Fig 1 . If voltage reading is more than 10.5 volts, go to next step. If voltage reading is 10.5 volts or less, repair open VPWR circuit (Red wire) between PCM power relay and FC relay. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  9 .
    Fig 1: Identifying Fan Control Relay 5-Pin Harness Connector Circuits
    G00155557Courtesy of MAZDA MOTORS CORP.
  3. Check For FC Circuit Cycling -  Connect a non-powered test light between VPWR circuit (Red wire) and FC circuit (Orange/White wire) at FC relay 5-pin harness connector. While observing test light, turn climate control selector switch from OFF to DEFROST several times. If test light turns on and off, replace faulty FC relay. After repair, go to step  9 . If test light does not turn on and off, repeat test step to verify results. If results are still the same, remove test light. Turn ignition off. Go to next step.
  4. Check Fan Control (FC) Circuit For Short To Power In Harness -  Disconnect PCM 104-pin harness connector. With KOEO, measure voltage between FC relay 5-pin harness connector FC circuit (Orange/White wire) and ground. See Fig 1 . If voltage reading is less than one volt, go to next step. If voltage reading is one volt or more, repair short circuit in Orange/White wire between PCM 104-pin harness connector terminal No. 45 and FC relay 5-pin harness connector. After repair, go to step  9 .
  5. Check FC Circuit For Short To Ground In Harness -  Turn ignition off. Disconnect scan tool from DLC. Measure resistance between FC relay 5-pin harness connector FC circuit (Orange/White wire) and ground. 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 in Orange/White wire between PCM 104-pin harness connector terminal No. 45 and FC relay 5-pin harness connector. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  9 .
  6. Check For Open FC Circuit -  Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure . Measure resistance of FC circuit (Orange/White wire) between breakout box terminal No. 45 and FC relay harness connector. See Fig 1 . If resistance reading is less than 5 ohms, replace faulty PCM. After repair, go to step  9 . If resistance reading is 5 ohms or more, repair open circuit in Orange/White wire between PCM 104-pin harness connector terminal No. 45 and FC relay 5-pin harness connector. After repair, go to step  9 .
  7. Check Fan Control (FC) Circuit For Open Or Short To Power -  Verify A/C and defrost are turned off. Disconnect cooling fan 5-pin harness connector. Connect a non-powered test light between VPWR circuit (Red wire) and ground at cooling fan 5-pin harness connector. See Fig 1 . With KOEO, turn climate control selector switch from OFF to DEFROST. Observe test light for an indication of a fault while completing the following (test light will turn off indicating a fault):
    • Shake, wiggle, and bend FC circuit between PCM and FC relay.
    • Shake, wiggle and bend VPWR circuit (Red wire) to FC relay.
    • Lightly tap on FC relay to simulate road shock.
    If a fault is not indicated, go to next step. If a fault is indicated, isolate fault and repair. After repair, go to step  9 .
  8. Check FC Circuit For Short To Ground -  Turn climate control selector switch from DEFROST to OFF. Observe test light for an indication of a fault while shaking, wiggling, and bending FC circuit between PCM and FC relay. Lightly tap on FC relay to simulate road shock. If a fault is indicated, isolate and repair wiring harness as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to next step. If a fault is not indicated, problem is intermittent. See INTERMITTENT  testing under SYSTEM TESTS.
  9. 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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