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Home >> Cadillac >> 2007 >> CTS Base, 2.8 T, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 747 (Cellular System, Entertainment System, And Navigation System) >> Diagnostic Information and Procedures >> DTC B128D >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2013 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON, place the navigation display in the down position.
  2. Ignition OFF, disconnect the X4 harness connector at the radio.
  3. Ignition ON, test for less than 1 volt between signal terminal 13 and ground.
    • If greater than specified range, test the signal circuit for a short to voltage. If circuit tests normal, replace the navigation display.
  4. Ignition OFF, test for infinite resistance between the signal terminal 13 and ground.
    • If less than specified range, test the signal circuit for a short to ground. If circuit tests normal, replace the navigation display.
  5. Ignition OFF, disconnect the X2 harness connector at the radio/HVAC display.
  6. Test for less than 5 ohms between the signal circuit terminal 13 X4 at the radio and terminal 5 X2 at the navigation display
    • If greater than specified value, test the circuit for an open/high resistance.
  7. If the circuit tests normal, replace the radio.
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