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Pcm Power Relay

  1. Check VPWR Circuit Resistance -  Disconnect Idle Air Control (IAC) valve 2-pin harness 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 reading is less than 5 ohms, reconnect IAC valve. Go to next step. If resistance reading is 5 ohms or more, repair open in VPWR circuit (Red wire) between PCM power relay and splice to IAC valve. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, restore vehicle to original condition. 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. After repair, restore vehicle to original condition. 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 reading was more than 10.5 volts, replace faulty PCM power relay. After repair, restore vehicle to original condition. Rerun QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If voltage reading is 10.5 volts or less, repair open in ground circuit (Black/White wire). See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, restore vehicle to original condition. Rerun QUICK TEST  under SELF-DIAGNOSTIC SYSTEM.
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