• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

For symptom byte information, refer to Symptom Byte List.

The body control module (BCM) activates the accessory wakeup serial data circuit, when the ignition key is in ACC, ON or START. The accessory wakeup serial data circuit wakes up the devices for serial data bus communication.

• The system voltage is between 9–16 V.
• The vehicle power mode master requires serial data communication to occur.

The BCM senses a short to ground on the accessory wakeup serial data circuit.

• The output command is turned off while the malfunction is present.
• The devices use a default value for the missing parameters until the next ignition cycle.
• The device(s) is never signaled. Therefore, the specific subsystem(s) will not function.
• The vehicle will not start while the circuit is shorted to ground.

• A current DTC clears when the malfunction is no longer present.
• A history DTC clears when the device ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

• Data Communication Schematics
• Control Module References

Master Electrical Component List

Data Link Communications Description and Operation

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Control Module References for scan tool information

1. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the harness connectors at the K9 Body Control Module. It may take up to 10 min for all vehicle systems to power down.
2. Test for greater than 100 Ω between the accessory wakeup serial data circuit terminal 22 X4 and ground.
• If 100 Ω or less
1. Disconnect the harness connectors at all devices that share the accessory wakeup serial data circuit.
2. Test for infinite resistance between the accessory wakeup serial data circuit terminal and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Reconnect the first device that shares the share the accessory wakeup serial data circuit.
4. Test for greater than 100 Ω between the accessory wakeup serial data circuit terminal and ground.
• If 100 Ω or less, replace the device that was just connected.
• If greater than 100 Ω and there are more devices to connect, connect the next device and repeat step 2.4 until there are no more devices to connect.
• If greater than 100 Ω
3. Replace the K9 Body Control Module.

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup