PIT5985

Bulletin No.: PIT5985
Published date: 02/28/2023
Preliminary Information
PIT5985 Diagnostic Tip: No Start/ Ignition Will Not Turn ON/ No Power Due To
A CAN bus 2 Issue/Lightning Strike/ Failed Over The Air Update
Models
Brand:
Model:
Model Years:
VIN:
from
to
Engine:
Transmissions:
Buick
Envision
2021 - 2023
All
All
All
All
Cadillac
CT4
2020 - 2023
All
All
All
All
Cadillac
CT5
2020 - 2023
All
All
All
All
Cadillac
Lyriq
2023
All
All
All
All
Cadillac
Escalade Models
2021 - 2023
All
All
All
All
Chevrolet
Corvette
2020 - 2023
All
All
All
All
Chevrolet
Silverado 1500 New (RPO J22, VIN Digit 12 = A or D)
2022
All
All
All
All
Chevrolet
Silverado 1500
2023
All
All
All
All
Chevrolet
Suburban
2021 - 2023
All
All
All
All
Chevrolet
Tahoe
2021 - 2023
All
All
All
All
GMC
HUMMER EV
2022 - 2023
All
All
All
All
GMC
Sierra 1500 New (RPO J22, VIN Digit 12 = A or D)
2022
All
All
All
All
GMC
Sierra 1500
2023
All
All
All
All
GMC
Yukon Models
2021 - 2023
All
All
All
All
Involved Region or Country North America
Some technicians may experience one or more of the following concerns:
Condition
1. No Start
2. Vehicle will not crank
3. Vehicle will not enter into Key On, Engine O mode (Service Mode)
4. Vehicle's Instrument Panel Cluster will not Illuminate
5. Vehicle will not shut O .
In addition to the above concerns, when using GDS2 to connect to the vehicle, the pop up message
seen below will be displayed, prompting to turn the ignition on, but the ignition can not be turned on.
In some cases, after several ignition button presses, the ignition may turn on. Then, the customer or
dealer technician may notice that blower motor turns on at a higher speed and then the ignition will
not be able to be turn O .
Cause
This may be caused by either an issue with Can Bus 2, the vehicle received an "Over The Air" (OTA)
update that has failed/ or the vehicle's electrical system was damaged by a voltage spike such as a
lightning strike or an incorrect jump start procedure.
Correction:
The following are some diagnostic tips to help isolate the concern:
1) Dealership technicians will notice that they are unable to access GDS data to review DTC's or check the network communication
status. They may experience the following pop up box, shown below, and will be unable to get past this screen. You will need to keep
hitting the continue button 5-6 times and then it will allow you to get past this screen and then it will be possible to go into vehicle
diagnostics to check DTC's and CAN bus status.
2) Next, use GDS2 Network Communication Status and check each CAN bus (1-8) to determine which modules are communicating
and which modules are not communicating. This is similar to the Detected State feature of the Data Bus Diagnostic Tool (DBDT), but
the DBDT will not work on these models. The GDS2 Network Communication Status can be found by following this GDS2 path:
Vehicle Diagnosis/Vehicle Communication Diagnostics/Network Communication Status.
Go through each CAN bus tab (CAN bus 1 -8) and note/document the communication status of each module. When switching from
tab to tab you may want to wait 25-30 seconds to see if modules show up. The picture below shows an example of CAN bus 2
status.
Diagnosis and repair any modules that are not communicating. If a module fails to communicate due to a failed OTA, rst try to
recover the module by reprogramming the module using SPS. Then clear all DTC's and recheck for concern.
3) If after all modules are communicating and you continue to have issues or current DTC: U1962, then perform a Serial Data
Authentication Con guration (SDAC), which is located on the SPS controller screen in the SPS, shown below. This will have to be
completed so each module recognizes each other on their respective data buses.
4) If the SDAC fails, it will attempt to run a total of 3 times. If it fails after the third attempt, an additional screen will pop up,
identifying which module is causing the SDAC to fail. Be patient, as this pop-up screen may take up to 25-30 seconds to appear. Take
a picture of the pop-up screen and reference the latest version of PIT5832.
5) If the SDAC passes and a labor code is generated, make sure to clear all the U codes that are current or the vehicle still may not
start.
Additional SI Keywords
U1960 U1961 U1962
Version History
Version
Modi ed
1
02/28/2023 - Created on
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