Service Bulletin

Bulletin No.: 13-08-116-001K
Date: March, 2025

TECHNICAL
Subject:

Aftermarket ALDL or DLC Interface Devices Causing Multiple Issues

Models:

2026 and Prior GM Passenger Cars and Trucks (including BrightDrop)

Attention:

This bulletin also applies to any of the above models that may be Export
from North America vehicles.

This bulletin has been revised to add the 2026 Model Year. Please discard Corporate
Bulletin Number 13-08-116-001J.
Condition
Important: Service agents must comply with all International, Federal, State, Provincial, and/or Local laws
applicable to the activities it performs under this bulletin, including but not limited to handling, deploying,
preparing, classifying, packaging, marking, labeling, and shipping dangerous goods. In the event of a
conflict between the procedures set forth in this bulletin and the laws that apply to your dealership, you
must follow those applicable laws.
Important: This technical service bulletin (TSB) can only be completed by BrightDrop dealers or BrightDrop certified
repair facilities who have met all BrightDrop specific training, tool, and equipment requirements. Repairs must be
performed by a technician who has successfully completed the required training.
Customers may comment on various issues with their vehicle related to high or low speed data bus traffic. These
concerns may be widely varied, but some of the known issues are listed below.
The information contained in this bulletin is not meant to single out any one device or symptom, but to provide
additional information that may be useful for diagnosing issues that do not have other diagnostic methods to identify
the root cause.
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.
Known Symptoms (not specific to any one device)
• The radio may not shut off after shutting down vehicle.
• Bus or LAN traffic may stay active leading to a discharged vehicle battery.
• Problems reprogramming modules either because of interference or the device will not allow the bus to power
down.
• ONSTAR® may lose the ability to provide diagnostic data.
• Various engine and transmission performance issues with SES light set.
• Intermittent driveability issues.
• Reduced power message and codes.
• Stabilitrak® message and codes.
• C0561 stored in the EBCM leading to a traction control issue.
• No high-speed LAN communication along with various communication U-codes.
• Transmission may not shift for one key cycle (TCM in default mode).
• Erratic gauge readings or flickering displays.

Copyright 2025 General Motors. All Rights Reserved.

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March, 2025

Bulletin No.: 13-08-116-001K

• SES, MIL, or CEL light set and numerous DTC communication codes such as U0100, U0101, U186B and
U1862.
• Diesel power-up devices causing no power in 4WD low range.
• Erratic electric power steering boost potentially associated with codes U2109, U2107, U2100, B1325, C0000.
• Battery run down
• Service Tire Pressure Monitoring (TPM) system light illuminated.
– Cannot relearn TPM
• Specific to Hybrids:
− Reduced propulsion power message.
− Service high voltage charging system message.

Cause
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. 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 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.
These devices may be removed by the customer for use in another vehicle while theirs is brought in for service. The
intent of this bulletin is to identify a potential source of concerns that do not have other diagnostic methods to identify
them. The examples below illustrate some of the devices encountered.
Examples:
The monitoring device examples are not specific to any one design, and styles will vary.
Device W/Secondary DLC Connector

3346643

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.

Bulletin No.: 13-08-116-001K

March, 2025

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Pedal Mounted Aftermarket Device Interface

3346646

Aftermarket Device at ALDL

3346648

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Bulletin No.: 13-08-116-001K

Aftermarket Device Switch

3346650

Monitoring Device Example

3346651

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March, 2025

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Fleet Tracking Device Interface (May Include Rental and Lease Vehicles)

3346652

Fleet Tracking Module Plugged Into the DLC

3346654

Correction
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.
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.
If the condition is not eliminated with the device removed, continue diagnosing the vehicle with the appropriate
Service Information.

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Bulletin No.: 13-08-116-001K

Parts Information
There should not be any parts required. If on the rare occasion parts appear to have been damaged by the device or
the installation of the device, this would not be a defect covered under the New Vehicle Limited Warranty. For more
information on Non-General Motors Parts & Equipment and Original Equipment Alterations, please refer to Article
1.2.2.12 of the Warranty Policy Information Manual. The repair order must be documented correctly stating factual
information on what alteration or product was identified on the vehicle.

Warranty Information
If ALDL interface devices are suspected as the root cause for a customer's concerns, submit a claim using the
0600014 Labor Operation to document the concern as detailed in the latest version of Corporate Service Bulletin
Number #09-00-89-016: Warranty Administration - Labor Operation 0600014 - Suspected Tampering or Vehicle
Modifications, including submitting the claim under the appropriate labor operation and selecting the Customer
Enthusiasm indicator in Global Warranty Management.
If a claim is submitted to GM, follow all existing guidelines within the Service Policies & Procedures and GWM User
Manual, GlobalConnect Messages, Bulletins, or any other communication format.
Labor
Operation

Description

Labor
Time

0600014

Suspected Tampering

0.2 hr

Additional SI Keywords: U0073, U0074, U0075, U0076, U0077, U007B, U007C, U007E, U0102, U0103, U010E,
U0121, U0125, U0126, U012A, U0131, U0132, U0136, U0137, U0139, U0140, U0142, U0146, U0151, U0154,
U0155, U0159, U0164, U0165, U0168, U0184, U0186, U0198

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job
properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.

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