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Circuit/System Testing

WARNING: This page is about a different car, the 2011 Chevrolet Caprice. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:

Use the schematic to determine which control modules are on the BCM communications enable circuit 19, X4.

  1. Ignition OFF, disconnect the harness connector at the most easily accessible control module on the K9 BCM accessory wakeup serial data circuit.
  2. Ignition ON, retest for current DTCs. DTC U1814 should remain current.
    • If the DTC becomes history, replace the control module that was just disconnected.
  3. With the prior control modules disconnected, repeat steps 1 and 2 for each control module on the circuit except the K9 BCM.
  4. Ignition OFF, disconnect the X4 harness connector at the K9 BCM.
  5. Test for infinite resistance between the serial data communication enable circuit terminal 19 X4 and ground.
    • If less than infinite resistance, repair the accessory wakeup serial data circuit for a short to ground.
  6. If all circuits tests normal, replace the K9 BCM.
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