PIT5481H
Service Bulletin Details
Public Details for: PIT5481H
This preliminary information communication provides information to the technician with additional information on the functionality of lane keep assist. Starting with 2016 model year lane keep assist regular production option code (uhx) repl
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Models from 2023
2023 CADILLAC ESCALADE ESV |
2023 CHEVROLET BLAZER |
2023 CHEVROLET SILVERADO 1500 |
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2023 CHEVROLET TAHOE |
2023 GMC SIERRA 1500 |
2023 GMC YUKON XL |
Models from 2022
2022 CADILLAC ESCALADE ESV |
2022 CHEVROLET BLAZER |
2022 CHEVROLET SILVERADO 1500 |
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2022 CHEVROLET TAHOE |
2022 GMC SIERRA 1500 |
2022 GMC YUKON XL |
Models from 2021
2021 CADILLAC ESCALADE ESV |
2021 CHEVROLET BLAZER |
2021 CHEVROLET SILVERADO 1500 |
2021 CHEVROLET SUBURBAN |
2021 CHEVROLET TAHOE |
2021 GMC SIERRA 1500 |
2021 GMC YUKON XL |
Models from 2020
2020 CADILLAC ESCALADE ESV |
2020 CHEVROLET BLAZER |
2020 CHEVROLET SILVERADO 1500 |
2020 CHEVROLET SUBURBAN |
2020 CHEVROLET TAHOE |
2020 GMC SIERRA 1500 |
2020 GMC YUKON XL |
Models from 2019
2019 CADILLAC ESCALADE ESV |
2019 CHEVROLET BLAZER |
2019 CHEVROLET SILVERADO 1500 |
2019 CHEVROLET SUBURBAN |
2019 CHEVROLET TAHOE |
2019 GMC SIERRA 1500 |
2019 GMC YUKON DENALI |
Models from 2018
2018 CADILLAC ESCALADE ESV |
2018 CHEVROLET SILVERADO 1500 |
2018 CHEVROLET SUBURBAN |
2018 CHEVROLET TAHOE |
2018 GMC SIERRA 1500 |
2018 GMC YUKON DENALI |
Models from 2017
2017 CADILLAC ESCALADE ESV |
2017 CHEVROLET SILVERADO 1500 |
2017 CHEVROLET SUBURBAN |
2017 CHEVROLET TAHOE |
2017 GMC SIERRA 1500 |
2017 GMC YUKON DENALI |
Models from 2016
2016 CADILLAC ESCALADE ESV |
2016 CHEVROLET SILVERADO 1500 |
2016 CHEVROLET SUBURBAN |
2016 CHEVROLET TAHOE |
2016 GMC SIERRA 1500 |
2016 GMC YUKON DENALI |
Bulletin No.: PIT5481H Published date: 11/14/2022 Preliminary Information PIT5481H Diagnostic Tip - Lane Keep Assist and Lane Departure Warning Functionality Models Brand: Model: Model Years: VIN: from to Engine: Transmissions: Cadillac Escalade Models 2016 - 2023 All All All All Chevrolet Blazer 2019 - 2023 All All All All Chevrolet Silverado 1500 2016 - 2023 All All All All Chevrolet Suburban 2016 - 2023 All All All All Chevrolet Tahoe 2016 - 2023 All All All All GMC Sierra 1500 2016 - 2023 All All All All GMC Yukon Models 2016 - 2023 All All All All With Lane Keep Assist (RPO UHX) Supersession Statement This PI was superseded to update the models. Please discard PIT5481G. This PI is to provide additional information on the functionality of Lane Keep Assist (LKA) and why customers may not get a lane departure warning alert (audible chime or haptic seat) when they cross a lane marker. The Lane Keep Assist system (RPO UHX) replaced the Lane Departure Warning (LDW) system (RPO UFL) starting with some models in 2016 model year. The LKA system incorporates the functionality of the LDW system, but it works slightly different when compared to a vehicle that only has LDW. Lane Keep Assist (LKA) has two driver interventions: Stage 1 and Stage 2. Lane Keep Assist is designed to assist the driver in keeping the vehicle from drifting out of a driving lane that has clearly identified lane markings (Stage 1). The electric power steering provides a gentle steering correction if a lane marking is being approached and the driver is NOT actively responding (i.e. NO driver steering wheel torque, accelerating, braking, use of turn signal). In situations where the LKA steering correction does not keep the vehicle from crossing the lane marker and the driver has NOT actively responded (ie. NO driver steering wheel torque, accelerating, braking, use of turn signal), then it enters Stage 2 and the LDW activates and provide an alert (chime or haptic seat). To help better understand Stage 1 and Stage 2: When Stage 1 is active: LKA icon changes from Green to a solid Amber. The Forward Camera Module is actively commanding a torque request to the Electronic Power Steering. This means that the driver should also feel some feedback from the steering wheel. There will be NO chimes or haptic seat feedback. Stage 1 occurs when approaching the lane marking. When Stage 2 is active: LKA icon changes from solid Amber to flashing Amber. The Forward Camera Module is actively commanding a torque to the Electronic Power Steering. This means that the driver should also feel some feedback from the steering wheel. This will also be accompanied with LDW chimes or haptic seat feedback, depending on vehicle settings. Stage 2 occurs when the vehicle has actually crossed a lane marking. The main difference between Stage 1 and 2, is when the vehicle enters Stage 2, the LKA icon will start to flash and a LDW alert (chime or haptic seat feedback) will occur. If the LKA icon does not flash, then there will be NO LDW alert (chime or haptic seat feedback). There are several reasons why the vehicle will not enter Stage 2, but the most common is the driver applying more torque to the steering wheel to overcome the LKA. This would lead to the LKA fading out, and as a result, the vehicle will not progress to Stage 2. Many drivers try to “test” the LDW alert (chime/haptic) by intentionally crossing the lane marker. It can be very difficult to "test" the LDW alert (chime/haptic), because the system most likely will see that the driver is intentional applying torque to the steering wheel, and it will interpret this as an active response. As a result, the system will NOT enter Stage 2. Therefore, LDW alerts do NOT occur as often with Lane Keep Assist when compared to a vehicle which only has the LDW system that was used in previous model years or on HD trucks. For Lane Keep Assist to start providing assist, the following criteria must be met: -Vehicle speed between 38 mph and 111 mph -Lane markings are clearly visible -Lane Keep Assist is turned "on" via the enable/disable button located on the dash. When enabled, the LED on the button will illuminate. -Lane marker width meets Lane Keep Assist criteria (not too wide or narrow) -Lane marker radius meets Lane Keep Assist criteria (curve is not too tight) When the criteria listed above is met, the Lane Keep Assist icon will illuminate, as seen in the photo below. The Lane Keep Assist icon has several different indication modes: - Solid green indicates the system is ready to assist. - Solid amber indicates Lane Keep Assist intervention is occurring - Stage 1. - Flashing amber indicates unintentional crossing of the lane marker along with a LDW alert (chime or safety seat vibration) - Stage 2. Lane Keep Assist and Lane Departure Warning alerts are suppressed with any deliberate driver response (ie. steering, accelerating, braking, use of turn signal, see below). Drivers can suppress/override Lane Keep Assist with the following deliberate maneuvers: - Turning the steering wheel (applying torque to the steering wheel) Intentional holding the steering wheel from turning when the LKA is trying to provide assist Braking Accelerating Turn signal is turned on in the direction of the lane crossing Proper operation may be affected by factors outside the vehicle, including: - Nearby vehicles ahead (tailgating) - Sudden lighting changes, such as going through a tunnel - Banked roads - Poor lane markings, such as on some two-lane roads - Snow, frost, ice, dirt, mud, bugs, etc on the windshield that are blocking the front camera - Tar marks, cracks, shadows, temporary lane markings and other road imperfections - Lane markings on one side of the road only (Lane Keep Assist provides assist only on the side with markings). The driver is advised to turn off the system when these conditions are present. This does not indicate a system failure. In addition, do not use Lane Keep Assist while towing a trailer or on a slippery road, as this may cause a loss of vehicle control. © 2022 General Motors. All Rights Reserved.