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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 16 (Transfer Case - Mp 3010 (NP0)) >> Diagnostic Information And Procedures >> DTC B0775: 4WD HI Indicator Circuit >> Component Testing >> BCM

Component Testing: BCM

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  1. Key OFF. Disconnect the X1 connector at the TCSCS.
  2. Using the L-BU probe J-35616-64B, connect a test light between the indicator dimming control circuit, TCSCS harness X1 pin 4 and a good ground.
  3. Key ON, engine OFF. The test light should be dull or OFF.
    • If the test light is bright, test the indicator dimming control circuit for a short to voltage condition. If all circuits and connections test normal, replace the BCM.
  4. Place a shop light on the DRL sensor. When the headlights go out the test light should illuminate brightly.
    NOTE: When the DRL sensor turns the headlights OFF the indicator dimming control circuit voltage, TCSCS X1 pin 4, will go from a diagnostic B+ to a true B+.
    • If the test light is dull or OFF, test the indicator dimming control circuit for an open/high resistance or short to ground condition. If all circuits and connections test normal, replace the BCM.
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