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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. DTC P1432: Check VPWR At THTRC Harness Connector -  Disconnect thermostat 2-pin harness connector. With KOEO, measure voltage of VPWR circuit (Light Blue/Orange wire) between thermostat harness connector and battery ground. 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 VPWR circuit (Light Blue/Orange wire) between thermostat harness connector and No. 41 fuse (20-amp) in under hood fuse relay box. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  6 .
    Fig 1: Identifying THTRC Connector Circuits
    G00155553Courtesy of MAZDA MOTORS CORP.
  3. Check Thermostat Resistance -  Turn ignition off. Measure resistance between terminals of thermostat connector. If resistance reading is 14-16 ohms, go to next step. If resistance reading is not 14-16 ohms, replace faulty thermostat. After repair, go to step  6 .
  4. Check THTRC Circuit For Open In Harness -  Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure . Measure resistance of THTRC circuit (Dark Blue wire) between breakout box terminal No. 46 and thermostat harness connector. See Fig 1 . If resistance reading is less than 5 ohms, go to next step. If resistance reading is 5 ohms or more, repair open circuit in Dark Blue wire between PCM 104-pin harness connector terminal No. 46 and thermostat harness connector. After repair, go to step  6 .
  5. Check THTRC Circuit For Short To Ground Or VPWR In Harness -  Measure resistance between breakout box terminals No. 46 and 71 and 97 (VPWR circuit). Record reading. Measure resistance between breakout box terminals No. 46 and 76, 77 and 103 (PWR GND circuit). If resistance reading is more than 10,000 ohms:
    • For Continuous DTC P1432, problem is intermittent. See INTERMITTENT  testing under SYSTEM TESTS.
    • For KOEO or KOER DTC P1432, replace faulty PCM. After repair, go to next step.
    If resistance reading is 10,000 ohms or less, repair short to VPWR or PWR GND. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to next step.
  6. Verify Trouble Shooting Of DTCs Completed -  Reconnect all electrical connectors. Clear DTC from PCM memory. 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.
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