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Home >> Mazda >> 2002 >> B4000 Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> System Tests >> Pcm Power Relay
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Pcm Power Relay

  1. Check VPWR Circuit Resistance

    Disconnect Idle Air Control (IAC) valve electrical connector. Disconnect scan tool from DLC. Disconnect PCM power relay. Measure resistance of VPWR circuit (Red wire) between IAC valve harness connector and PCM power relay connector. If resistance is less than 5 ohms, reconnect IAC valve. Go to next step. If resistance is 5 ohms or more, repair open VPWR circuit between PCM power relay and splice to IAC valve. See WIRING DIAGRAMS article. Restore vehicle. Rerun QUICK TEST  under SELF-DIAGNOSTIC SYSTEM.

  2. Check B+ & IGN START/RUN Voltage To PCM Power Relay

    Measure B+ circuit (Yellow wire) at PCM power relay connector. Record reading. With KOEO, measure voltage of IGN START/RUN circuit (Tan/Black wire) at PCM power relay connector. Record reading. If both voltage readings are more than 10.5 volts, go to next step. If either voltage reading is 10.5 volts or less, turn ignition off. Repair open in B+ circuit (Yellow wire) or IGN START/RUN circuit (Tan/Black wire), and verify condition PCM diode. See WIRING DIAGRAMS article. Restore vehicle. Rerun QUICK TEST  under SELF-DIAGNOSTIC SYSTEM.

  3. Check Ground Circuit To Power Relay

    Measure voltage between B+ circuit (Yellow wire) and ground circuit (Black/White wire) at PCM power relay connector. Turn ignition off. If voltage is more than 10.5 volts, replace faulty PCM power relay. Restore vehicle. Rerun QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If voltage is 10.5 volts or less, repair open ground circuit. See WIRING DIAGRAMS article. Restore vehicle. Rerun QUICK TEST  under SELF-DIAGNOSTIC SYSTEM.
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