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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 B0770: AWD Indicator Circuit >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, and 2018 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.
  1. Remove key. Disconnect the X1 connector at the transfer case shift control switch (TCSCS).
    NOTE: When test probing harness terminals, it is imperative to use the proper test probe from the most current version of the J-35616  GM terminal test kit. Use of an improper test probe may deform the terminal, resulting in intermittent open conditions.
  2. Door open, key ON, engine OFF.
  3. Using the L-BU probe J-35616-64B, test for a diagnostic B+ (+0.0/-1.0 V) between the indicator dimming control circuit, TCSCS X1 pin 4 and a good ground, such as the ground terminal of the EL-49742  harness, black terminal.
    • If the voltage is less than the specified range, test the affected circuit for an open/high resistance, short to ground, or short to voltage. If all circuits and connections test normal, test the body control module (BCM) for proper operation.
  4. Using the L-BU probes J-35616-64B, test for a diagnostic B+ (+0.0/-1.0 V) between the indicator dimming control circuit, TCSCS X1 pin 4 and the AWD indicator control circuit, TSCSC X1 pin 7.
    • If the voltage is less than the specified range, test the AWD indicator control circuit for an open/high resistance or short to power. If all circuits and connections test normal, test the TCCM for proper operation.
  5. Key OFF. Using the L-BU probe J-35616-64B, test for greater than 10 Ω between the indicator dimming control circuit, TCSCS X1 pin 4 and all other pins of the TCSCS X1.
    • If the resistance is less than the specified range, test the affected circuits for a shorted together condition. If all circuits and connections test normal, test the TCCM for proper operation.
  6. Using the L-BU probe J-35616-64B, test for greater than 10 Ω between the 4WD HI indicator control circuit, TCSCS X1 pin 7 and all other pins of the TCSCS X1.
    • If the resistance is less than the specified range, test the affected circuits for a shorted together condition. If all circuits and connections test normal, test the TCCM for proper operation.
  7. Test the TCSCS for proper operation.
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