Manufacturer communication — 2006 GMC YUKON DENALI XL

• Applies to 2021 and earlier GM passenger cars and trucks.

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  Models: 2021 and Prior GM Passenger Cars and Trucks

• The radio may not shut off after the vehicle is shut down, and bus or LAN traffic may stay active, leading to a discharged battery.

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  • The radio may not shut off after shutting down vehicle. • Bus or LAN traffic may stay active leading to a discharged vehicle battery.

• C0561 may be stored in the EBCM, leading to a traction control issue, and there may be no high speed LAN communication with various communication U-codes.

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  • C0561 stored in the EBCM leading to a traction control issue. • No high speed LAN communication along with various communication U-codes.

• The SES, MIL or CEL light may be set 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.

• The transmission may not shift for one key cycle (TCM in default mode), and gauge readings may be erratic or displays may flicker.

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  • Transmission may not shift for one key cycle (TCM in default mode). • Erratic gauge readings or flickering displays.

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 be caused by 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 diagnostics find no 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 identify 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 customer may remove the device for use in another vehicle while theirs is in for service.

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  These devices may be removed by the customer for use in another vehicle while theirs is brought in for service.

• Some devices carry a second DLC connector, with the device and the rest of the harness hidden out of sight, so the technician may not notice that the diagnostic connector is not in the factory location.

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  This device has another DLC connector on it. 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.