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Home >> Cadillac >> 2018 >> Escalade ESV Platinum, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 16 (Transfer Case - Mp 3010 (NP0)) >> Diagnostic Information And Procedures >> DTC B0770: AWD Indicator Circuit >> Component Testing >> TCCM

Component Testing: TCCM

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. Key OFF. Disconnect the X1 connector at the TCSCS.
  2. Key ON, engine OFF.
  3. Using the L-BU probe J-35616-64B, test for 4.5 - 5.5 V between the 5-volt reference circuit, TCSCS harness X1 pin 11 and a good ground.
    • If the voltage is greater than the specified range, test the 5-volt reference circuit for a short to voltage. If all circuits and connections test normal, replace the TCCM.
    • If the voltage is less than the specified range, test the 5-volt reference circuit for an open/high resistance or short to ground. If all circuits and connections test normal, replace the TCCM.
  4. Using the L-BU probes J-35616-64B, connect a test light between the 5-volt reference circuit, TCSCS harness X1 pin 11 and a good ground. The test light should illuminate dimly.
    • If the test light does not illuminate, obtain a different test light and repeat step 4.
  5. Key OFF. Wait 30 seconds for the TCCM to shut down.
  6. Using the L-BU probes J-35616-64B, connect a test light between the TCSCS harness as specified below for the LED control circuit being tested.
    NOTE: The TCCM must see the added resistance of the test light on the control circuit at key ON or the TCCM will shut the control circuit drivers OFF. Volt meters will not work for this test.
  7. Key ON, engine OFF.
  8. Using the Special Function ability of the scan tool, command the affected LED ON and OFF. The test light should turn OFF and ON as commanded.
    • If the test light remains illuminated when commanded OFF, test the affected control circuit for a short to ground. If all circuits and connections test normal, replace the TCCM.
    • If the test light remains OFF when commanded ON, test the affected control circuit for an open/high resistance or short to voltage. If all circuits and connections test normal, replace the TCCM.
Mode 2WD HI 4WD Auto 4WD HI 4WD LO N
5-V Reference (pin) 11 11 11 11 11
Indicator Control Circuit (pin) 8 7 9 10 3
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