Manufacturer communication — 2006 GMC YUKON DENALI XL

• 2025 and prior GM passenger cars and trucks (including BrightDrop).

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  2025 and Prior GM Passenger Cars and Trucks (including BrightDrop)

• The bulletin is written with a focus on full size trucks, full size vans and other fleet vehicles, but could apply to any vehicle.

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  Note: This bulletin is being written with a focus on full size truck and full size van along with other fleet vehicles, but could apply to any vehicle.

• Customers report various issues related to high or low speed data bus traffic.

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  Customers may comment on various issues with their vehicle related to high or low speed data bus traffic.

• Bus or LAN traffic may stay active, leading to a discharged vehicle battery.

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  Bus or LAN traffic may stay active leading to a discharged vehicle battery.

• C0561 stored in the EBCM, leading to a traction control issue.

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  C0561 stored in the EBCM leading to a traction control issue.

• SES, MIL or CEL light on with numerous communication DTCs such as U0100, U0101, U186B and U1862.

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  SES, MIL or CEL light set and numerous DTC communication codes such as U0100, U0101, U186B and U1862.

Possible causes

• Monitoring devices and other electronic accessories such as aftermarket cruise control or police speed checking devices (RADAR or LIDAR) may cause one or more of the listed concerns.

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  Monitoring devices, along with other electronic accessories such as aftermarket cruise control, or police speed checking devices (RADAR or LIDAR) may cause one or more of the concerns listed above.

• Many of the problems could come from an open connection on the HSCAN bus; a device that connects to only one CAN + causes bus errors and erratic ECU behavior.

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  Many of the problems described could be caused by an open connection on the HSCAN bus. Example: if the device only makes connection with one CAN +, then it will cause bus errors and erratic ECU behavior.

Steps to confirm (in the document’s order)

• If normal SI diagnostics find no other root cause, check for a device plugged into the ALDL or Data Link Connector (DLC) for tracking and/or maintenance interval scheduling.

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  If nothing else can be identified as the root cause of the issue after normal diagnostics as found in SI, check for a device plugged into the Assembly Line Diagnostic Link (ALDL) or Data Link Connector (DLC) for tracking and/or maintenance interval scheduling.

Repair

1. If SI diagnostics do not find the source and the device is available, try to duplicate the condition, then remove the device to see whether the condition is eliminated.

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   If SI diagnostics do not identify the source of the issue and if the device is available, attempt to duplicate the condition, and then remove the device to determine if the condition is eliminated.

2. If removing the DLC interface device resolves the concern, tell the customer the result and that they should work with the device's supplier for further resolution.

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   If the customer’s concern is resolved by removing the DLC interface device, inform the customer of the results, and that they should work with the supplier of the device for further resolution.

Caution

• The device and the rest of its harness can be hidden out of sight, and the technician may not notice that the diagnostic connector is not in the factory location.

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  The rest of the harness along with the device can be placed out of sight hidden from the technician, who may not notice the diagnostic connector is not in the factory location.