Service Bulletin

Bulletin No.: 07-08-42-006T
Date: March, 2025

INFORMATION
Subject:

Information on Available BCM Calibrations to Restore Bulb Outage Detection
on Vehicles Produced by a Second Stage Manufacturer (Upfitter), Turn Signals
Flash Fast after Factory Box Removed

Models:

2007-2018 Chevrolet Silverado
2019 Chevrolet Silverado LD
2019 Chevrolet Silverado 1500 (New Model)
2019 Chevrolet Silverado 2500/3500
2020-2021 Chevrolet Silverado 1500
2020-2025 Chevrolet Silverado 2500HD/3500HD
2022-2022 Chevrolet Silverado 1500 New (RPO J22, VIN Digit 5 = A / D)
2023-2025 Silverado 1500
2007-2018 GMC Sierra
2019 GMC Sierra Limited
2019 GMC Sierra 1500 (New Model)
2019 GMC Sierra 2500/3500
2020-2021 GMC Sierra 1500
2020-2025 GMC Sierra 2500HD/3500HD
2022-2022 GMC Sierra 1500 New (RPO J22, VIN Digit 5 = H / U)
2023-2025 GMC Sierra 1500

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 Important statement, 2024 Model Year to
applicable models and information. Please discard Corporate Bulletin Number
07-08-42-006S.
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.
• The information contained in this bulletin applies only to 2500 and 3500 Series trucks that are to be completed
by a second stage manufacturer (upfitter) and may need to have the Body Control Module (BCM) rear turn
signal bulb outage detection capability changed.
• 2014 and earlier 1500 Series trucks only have Option #1 available.
Production vehicles will be manufactured with one of the following BCM rear turn signal bulb outage
detection software options:
1. A standard production vehicle will have BCM software that checks for two bulbs functioning in each rear turn
signal bulb circuit. If one or more bulbs are inoperative, the BCM will “fast flash” the Instrument Panel Cluster
(IPC) turn signal indicator as required by Federal Motor Vehicle Safety Standard (FMVSS) 108 and Canada
Motor Vehicle Safety Standard (CMVSS) 108.

Copyright 2025 General Motors. All Rights Reserved.

Page 2

March, 2025

Bulletin No.: 07-08-42-006T

2. Certain 2500 and 3500 models can be ordered with a new option (RPO 9U5) where the BCM checks for one
bulb functioning in each rear turn signal bulb circuit. If the bulb goes inoperative, the BCM will “fast flash” the
Instrument Panel Cluster (IPC) turn signal indicator as required by Federal Motor Vehicle Safety Standard
(FMVSS) 108 and Canada Motor Vehicle Safety Standard (CMVSS) 108.
3. Models built with a pickup box delete or chassis cab option (RPO ZW9) will be produced with a BCM program
that has no turn signal bulb outage detection capability (LED compatible). The IPC turn signal indicator will flash
at the same rate no matter how many turn signal bulbs are inoperative.
Note: For 2015 – 2024 trucks, B3951 & B3950 DTCs for rear tail lamps could set on any truck (ZW9 or E63) if LED
lamps are installed (or lamps are inoperative). This code is used as an assembly verification but does not affect the
function of a properly operating system with LED lights installed.
In some cases, the upfitter may wish to change the turn signal bulb outage detection capability so that the turn
signals work correctly with their upfit or to meet certain requirements. This will require contacting the Techline
Customer Support Center (TCSC) (1-800-828-6860 English or 1-800-503-3222 French) to open a case and obtain a
Vehicle Configuration Index (VCI) number. Advise the TCSC consultant which turn signal bulb outage detection
capability is needed from the following list:
1. Factory standard production TWO bulb outage detection.
2. Optional (RPO 9U5) ONE bulb outage detection.
3. NO bulb outage detection (LED compatible).
Notice: This option is only available on 2015 – 2024 trucks and is included on trucks built with the RPO ZW9
box delete option.

The BCM can then be reprogrammed with the correct software.

Warranty Information
As with any vehicle modifications these changes and expenses (from TCSC, parts, labor or other expenses) should
not be considered warrantable repairs and should not be charged under warranty. These modifications are
considered customer pay. No labor operation is provided.

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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