Malfunction Indicator Lamp (MIL) Illuminated – DTC P026A Set – 2017-2023 Chevrolet Silverado & GMC Sierra

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Copyright 2022 General Motors LLC. All Rights Reserved. Service Bulletin Bulletin No.: 18-NA-011 Date: September, 2022 INFORMATION Subject: Information On Malfunction Indicator Lamp (MIL) Illuminated – DTC P026A Set Attention: This bulletin only applies to vehicles that have a snow plow installed. Brand: Model: Model Year: VIN: Engine: Transmission: from to from to Chevrolet Silverado Models 2017 2018 L5P All Silverado 2500/3500 2019 2023 GMC Sierra Models 2017 2018 Sierra 2500/3500 2019 2023 Involved Region or Country North America Condition Some customers may comment that the MIL is illuminated Some technicians may find DTC P026A set on vehicles with a snow plow installed. Information Note: When a snow plow is attached to the vehicle, the customer should always monitor the coolant temperature. Important: There is an aftermarket accessory that can help with this condition. Additional information can be found at www.gmupfitter.com, then search UI Bulletin #131b under Technical Bulletins. Some snow plows when installed onto vehicles, will change the airflow entering the grill and effect the efficiency of the coolers in the front of the vehicle. Per Owner’s Manual, a vehicle with a plow installed should not exceed 45MPH (72 km/h). Vehicles that exceed 45MPH (72 km/h) may cause the engine to overheat and cause internal engine damaged. Vehicles that are driven over 45MPH (72 km/h), DTC P026A will set if the air flow is restricted into the coolers. When driven under 45MPH (72 km/h), DTC P026A will not set at or below this speed. Please refer to the Owner’s Manual under Adding a Snow Plow or Similar Equipment (refer to SI Document ID 4501631). Version 6 Modified Released January 16, 2018 Revised January 29, 2019 – Added 2019 Model Year and GM Upfitter Website Information. Revised August 07, 2019 – Add 2020 to Model Year. Revised October 27, 2020 – Add 2021 to Model Year. Revised January 11, 2022 – Add 2022 to Model Year. Revised September 09, 2022 — Added the 2023 Model Year. 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. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

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UI Bulletin #131c General Motors Upfitter Integration http://www.gmupfitter.com Bulletin #131c P a g e | 1 March 1, 2019 Disclaimer: GM Upfitter Integration Technical 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 and/or modification of a vehicle. These 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. Contact GM Upfitter Integration for information on whether the information is applicable your vehicle. Subject: Elevated Engine Coolant/Operating Temperatures with Snow Plow Mounted Models Years Affected: 2014 and beyond Models Affected: Chevrolet Silverado GMC Sierra Upfitted with a Snow Plow Origination Date: June 1, 2016 Revision Date: March 1, 2019 ADVISORY: Condition/Concern: Some customers may express concern about one or both of the following when a snow plow is attached to the front of the trucks: 1. Higher than normal engine or transmission temperature. 2. Incorrect outside temperature reading. Both of the above conditions can occur due to the reduced airflow into the radiator area with the plow in the raised position. The air flow is diverted upward as a result of the raised plow and thereby does not enter the front grille area of the vehicle. Repair/Recommendation: In many situations, the following steps may improve air flow to the front of vehicle/grill area to improve cooling and/or reduce operating temperatures: • Try lowering or repositioning (angling) of the plow. • If repositioning attempts are unsuccessful in reducing the operation temperature, GM recommends that an after-market air deflector be added to the top of the plow, similar to the one shown below. Note: Per vehicle Owner Manual “Caution: Do not exceed 64 km/h (40 mph) with a snow plow mounted to the vehicle. The vehicle could overheat and be damaged.”

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