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Home >> Hyundai >> 2017 >> Azera Base >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System Diagnosis (3 Of 3) >> DTC P0685: ECM/PCM Power Relay Control Circuit/Open >> Component Inspection
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Component Inspection

Check Main relay 

  1. IG "OFF" and disconnect main relay.
  2. Measure the resistance between battery power supply and control terminals of main relay. (Measurement "A")
  3. Measure the resistance between battery power supply and power supply to PCM terminals of main relay. (Measurement "B")

    Specification: 

    Terminal Continuity
    Battery power supply - Power supply to PCM Measurement "B" NO
    Battery power supply - Main relay control Measurement "A" YES (Approx. 70Ω ~ 120Ω)
    Fig 1: Measuring Resistance Between Battery Power Supply And Control Terminals Of Main Relay (Measurement A)
    G12090174Courtesy of HYUNDAI MOTOR AMERICA
  4. Is the measured resistance within specification?

    YES 

    • Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair " procedure.

    NO 

    • Substitute with a known - good Fuel Pump Relay and check for proper operation. If the problem is corrected, replace Fuel Pump Relay and go to "Verification of Vehicle Repair " procedure.