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Home >> Cadillac >> 2014 >> Escalade Base, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 6 (Transfer Case - Mp 3023/3024-NQH) >> Diagnostic Information and Procedures >> DTC P279A: Four Wheel Drive (4WD) High Range Performance >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2014 GMC Yukon XL 1500, 2014 GMC Yukon, 2014 Chevrolet Tahoe, and 2014 Chevrolet Suburban 1500. However, it is still accessible from the selected car via links, so may be relevant.
  1. Observe the 4WD Signal in the ECM Data List. The 4WD signal should display Enabled when you shift into 4WD and Disabled when you shift into 2WD.
    • If the scan tool display does not match the transfer case range switch state, repair the transfer case system. Refer to Diagnostic System Check - Vehicle .
    • If the scan tool matches the transfer case range switch state, continue with testing.
  2. Program the ECM with the latest software version and retest for DTCs.
    • If the DTC resets, replace the ECM.
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