23-NA-151 Service Bulletin/Repair Instructions

Bulletin No.: 23-NA-151
Service Bulletin
Date: May, 2025
INFORMATION

Subject:
Brand:
Hybrid/EV Battery Stability, High Priority DTCs, Potential Loss of Isolation,

Vehicle Handling and Battery Pack Return Shipping Requirements

Model:
Model Year:

from
BrightDrop
Cadillac
Chevrolet
GMC
VIN:

to
from
EV600
2022
2022
Zevo 600
2023
2024
Zevo 400
2024
2024
CELESTIQ
2025
2025
LYRIQ
2023
2025
OPTIQ
2025
2025
Escalade IQ
2025
2026
Escalade IQL
2026
2026
VISTIQ
2026
2026
Blazer EV
2024
2025
Equinox EV
2024
2025
Silverado EV
2024
2025
BrightDrop 400
2025
2025
BrightDrop 600
2025
2025
HUMMER EV Pickup
2022
2025
HUMMER EV SUV
2024
2025
Sierra EV
2024
2025
Involved Region or Country
Information
Engine:
—
Transmission:
to
—
All
All
North America, Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Egypt, Europe,

Cadillac Korea (South Korea), GM Korea Company, Japan, Palestine, Israel, Middle

East, Kazakhstan, Australia/New Zealand

This bulletin and criteria within are to determine the internal stability of the High Voltage

Battery and the core return shipping method.

If a vehicle arrives with any of the DTCs on the list, additional checks need to occur to

give proper direction on isolated vehicle storage guidance and repair instructions and

results MUST be documented in a TAC Case.

Perform the service instruction steps as indicated if any of the following DTCs listed are

set as CURRENT:

DTCs: P0AA6, U359E, P0AE3, P0C78, U1666, U1667, U2BFC, P1C34, OR P0AA7 set

by itself, OR if any of these DTCs are listed as HISTORY:

• P0AA6

• U359E

OR if directed here by a service procedure such as High Voltage System Inspection

(physical battery damage observed) or TAC.
Service Procedure

Warning: Never leave a vehicle or battery pack with an applicable DTC indoors overnight, plan all work to be

completed during normal business hours.
Copyright 2025 General Motors. All Rights Reserved.
Page 2
May, 2025
Bulletin No.: 23-NA-151
Danger: Failure to use the proper Personal Protective Equipment and failure to carefully follow these procedures may result in serious injury or death.

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 certified repair facilities who have met all

specific training, tool and equipment requirements pertaining to the vehicle Brand and Model serviced. Repairs must

be performed by a technician who has successfully completed the required training.

Important: Please review the data thoroughly. GM will not authorize core return shipment requests without proper

review, which could lead to non-return core fee charges. It is essential to complete all steps outlined below and

provide data to TAC for review and further direction, to avoid delays in the pick-up the high voltage battery core and

prevent any duplication of work.

Note: Steps outlined below can also be found on Center of Learning Course # 59520.14V.

1. Verify if DTCs U2BFC or P1C34 are set as current. If yes, immediately report results to TAC now as review will

be necessary to help determine stability.

2. Verify any of the following DTCs are set as CURRENT; P0AA6, P0AE3, P0C78, P1C34, U359E, U1666, U1667

or P0AA7 without other propulsion DTCs. Verify if the following DTCs are set as HISTORY: P0AA6 or U359E.

3. Obtain and document a clear and thorough description of the concern from the customer. Was the vehicle towed

because of a no start concern or loss of propulsion, did they hear a ‘pop’ or abnormal noise.

Danger: DO NOT add coolant without first confirming the Lithium-Ion Hybrid/EV Battery Pack internal

coolant passage can maintain proper vacuum and pressure. Adding coolant to the coolant system with an

internal lithium-ion Hybrid/EV Battery Pack coolant leak may result in Fire, which could result in vehicle or

component damage, and cause severe body injury or death.

4. Visually inspect the coolant level in the high-voltage battery surge tank (Fig 1 and 2) and document via photo.

Inform TAC if coolant has previously been added.

Note: This Data is found in K16 – Battery Energy Control Module -> Data Display -> Hybrid/Electric Vehicle Battery

Pack Thermal Stability Data.
6856200
5. Observe and record GDS2 data (Fig 3) :

• Most Recent Isolation Resistance - Pack and Pack 2 (as applicable). Greater than 6200K ohms is normal.

• Thermal Event Temperature Sensor. Near ambient and close to all other temperature sensors is normal.
Bulletin No.: 23-NA-151
May, 2025
Page 3
• Thermal Event Gas Sensor. 0 to 30,000 ppm and not rising is normal.

• Thermal Event Pressure Sensor. Near barometric pressure and not rising is normal.

• Interface Control Module Temperature (1 thru 24 as applicable). Near ambient and close to all other temperature sensors is normal.

6. If the vehicle is already on a hoist, you may perform the battery pack inspection steps that do not require battery

pack removal to perform.

7. Perform SPS2 Hybrid/EV Battery Data Retrieval, refer to 25-NA-044.

Danger: Damage to a Lithium-Ion hybrid/EV battery pack could result in fire, loss of electrical isolation or

exposure to high voltage. Until the high voltage system inspection has been completed, store the vehicle

with hybrid/EV battery pack installed outside in a secure area away from buildings and other vehicles and

protected from rain, snow, and other moisture.

8. Move the vehicle to a stable location outdoors: isolated and away from buildings, vehicles, and foot traffic while

waiting direction to diagnose/repair. Recommended distance is 50 feet (15M). Document isolated location via

photo (Fig 4 and 5). Refer to ‘Neutral Service Mode’ in electronic transmission range select service information if

required.

9. Start a TAC case and upload all photos and your GDS2 session log per Document ID: 6385557 / PIP4902 and

reference this bulletin. Additionally, provide any previous diagnosis work performed based on the DTC(s) set or

inability to collect the data.

Note: Perform the following steps at time of High Voltage Battery replacement. Depending upon the following results

you may be required to immediately move the High Voltage Battery outdoors after removal. Do NOT submit a core

pickup request unless given approval by TAC.

10. Following SI Procedure for high voltage battery removal, Hybrid/Electric Vehicle Battery Pack Removal, and

Installation:

10.1. Inspect the High Voltage Connectors at the High Voltage Battery for corrosion, moisture, and/or soot.

Take clear, close-up photos of the vehicle side HV connectors and High Voltage Battery connection

headers. Review Fig 8-10 for examples of light and heavy soot and the photo clarity required. Attach

photos to TAC Case.

Note: If soot, corrosion or moisture is observed, continue but contact TAC immediately upon completion.

10.2. Check for High Voltage at the Hybrid/Electric Vehicle Battery Pack X1 through X7 (as equipped) by

following High Voltage Disabling – High Voltage Disable Confirmation Table – A4 Hybrid/EV Battery

Pack in Service Information (Fig 6 and 7).

Note: If more than 3V is found, continue but contact TAC immediately upon completion.

10.3. Remove the High Voltage Battery Pressure Equalizer Vent and Battery Inspection plug (if equipped) (Fig

11 and 12). The equalizer vents have 4 fasteners and are located at the base of the battery. Wearing your

personal protection equipment use a cotton swab or paper towel to swab inside the enclosure for

moisture/coolant and/or soot. Take photos and attach to TAC case.

Note: Swabs are available in a pack of 20 as GM-47909-20.

Note: If fluid/soot is observed, continue but contact TAC immediately upon completion.

Danger: Do not insert anything other than a cotton swab or paper towel while performing the swab test.

10.4. Evacuate residual coolant from the High Voltage Battery coolant circuit. Refer to the SI Procedure for

Hybrid/Electric Vehicle Battery Pack Replacement and Shipping Preparation.

Note: If unable to remove coolant from the High Voltage Battery coolant circuit, continue but contact TAC immediately upon completion.

10.5. Vacuum test the High Voltage Battery coolant circuit for leaks. See Hybrid Battery Pack Coolant Passage

Leak Test (Fig 13 and 14). Attach photos to the TAC case.

Note: If the High Voltage Battery coolant circuit does not hold vacuum, continue but contact TAC immediately upon

completion.

10.6. Pressure test the High Voltage Battery coolant circuit for leaks (Only complete if passes vacuum test).

See Hybrid Battery Pack Coolant Passage Leak Test (Fig 15 and 16). Attach photos to the TAC case.

Note: If the High Voltage Battery coolant circuit does not hold pressure, continue but contact TAC immediately upon

completion.
Page 4
May, 2025
Bulletin No.: 23-NA-151
11. Place the High Voltage Battery in the provided DDR Crate & move outdoors: isolated and away from buildings,

vehicles, and foot traffic. Cover high voltage battery/DDR crate with a tarp to protect from the elements while

awaiting further direction (Fig 4). Take picture of location and upload into TAC Case. Report all results to TAC

for Engineering review.
23-NA-151 Hybrid/EV Stability Printable Checklist for VIN:_________________________________

Initial Vehicle Inspection

Steps
Results
Submission Check List
Inspect Coolant Level. Photograph result.

Danger: DO NOT add coolant without

first confirming the Lithium-Ion

Hybrid/EV Battery Pack internal coolant

passage can maintain proper vacuum

and pressure. Adding coolant to the

coolant system with an internal lithiumion Hybrid/EV Battery Pack coolant leak

may result in Fire, which could result in

vehicle or component damage, and

cause severe body injury or death.
Passed Example

Refer to Figure 1
Failed Example

Refer to Figure 2
Coolant Level Photo

__________
GDS2 Session Log. Battery Energy Control

Module>Data Display>Hybrid/Electric

Vehicle Battery Pack Thermal Stability Data
Refer to Figure 3
Pack Isolation

1___________ohms

2___________ohms

Thermal Sensor

__________C/F

Thermal Gas

__________PPM

Thermal Pressure

__________psi/kPa

Interface Temperature

(average)

___________C/F
GDS2 -Vehicle Battery Pack

Thermal Stability Data

Captured

__________
Move vehicle to stable location away from

buildings and other vehicles.

Recommended isolation distance is 50 feet

(15M) Photograph results.

Warning: Never leave a vehicle or battery pack with an applicable DTC indoors overnight, plan all work to be

completed during normal business hours.
Passed Example

Refer to Figure 4
Failed Example

Refer to Figure 5
Vehicle Isolated Outside and

Picture Captured/Submitted

__________
Start TAC Case (submit all the above).
Vehicle to stay isolated outdoors until Hybrid/

Electric Vehicle Battery Pack Removal and

Installation or under the direction of TAC during

any required diagnosis procedure.

SaleBestseller No. 1

ANCEL X7HD 10'' Heavy Duty Truck Scanner, Semi Trucks Full System Diagnostic Tool, Bidirectional Diesel Scan Tool with DPF, ECU Coding, 40+ Reset for Cummins, Detroit, Caterpillar, Volvo, Paccar etc

🔥🔥🔥2026 New Functions Making X7HD the Top Dog - Big Surprise!!! ANCEL X7HD truck scanner 10 major functional advantages .✅>Full HDOBD/OBD2 Function ✅>ALL System Diagnostic ✅>42+ Reset Function ✅>Active Test / Bi-Directional Control✅>ECU Coding✅>Graphing Live Data✅>Wide Compatibility ✅>2 Yrs Free Update✅>Remote Operation✅>Bluetooth 5.0 & Wifi In addition, 8 major hardware advantages: ✅>6000 mAh✅>10.1 inch Tablet✅>2G RAM✅>32G ROM (Expandable to 128GB)✅>Data Record & Replay & Print✅>Android 10.0✅>Bluetooth 5.0 & Wifi✅>14 Languages
🚛OEM DPF Forced Regen & Cylinder Cutout Test & more - ANCEL X7HD diesel scanner diagnostic tool not only supports DPF regeneration, DPF reset, DPF related information reset, DPR state reset, DPD forced regeneration etc, which helps you better solve the exhaust aftertreatment system problems, but also supports activate motor to do exhaust air in ABS Automatically. Moreover, it features TPMS activation, cylinder cut-off and learning functions
🚛Advanced ECU Coding & Programming - ANCEL X7HD 10.1inch truck scanner diagnostic tool is equipped with advanced ECU coding, supports Level calibration, Idle speed learning and Adjustment, Camshaft timing control learning, Control unit adaptations, Injector Codes, Read/Write VIN, Road speed limit optional vehicle speed set, etc... PLEASE NOTE that ECU codes are not compatible with all vehicles, please send us your VIN# to check vehicle compatibility
🚛42+ Reset Functions & Bidirectional Control - 2026 newest top heavy duty truck scan tool, comes with 42+ special services (ECU, Speed Limit and Idle Reset, Oil Reset, Injector Coding, EPB, ABS, SRS, Suspension, Throttle, etc. and always keep growing), which meet all your various needs for service and maintenance
🚛10 Inch All Systems Diesel Scanner & Full HDOBD/OBD2 Modes - ANCEL X7HD diesel truck scan tool supports all systems scan, such as Engine, Brake, Retarder, TECU Transmission, Tachograph, ABS, SRS, TPMS, EPB, SAS, ESP, and other vehicle systems, comes with 10 obd2 service modes: read/erase error codes, Data Stream, I/M Readiness, Vehicle Information, Actuations, DTC Lookup, EVAP, view freeze frame, etc

SaleBestseller No. 2

ANCEL Heavy Duty Truck Scanner HD601 All System Diesel Diagnostic Scan Tool fits for Cummins, Detroit, Freightliner, International, Paccar, Check Engine for Truck & Car 2 in 1 Code Reader

【Extensive Compatibility】HD601 heavy duty truck scanner supports 12V & 24V commercial vehicles and all major truck models that comply with standard protocols (SAE J1939, SAE J1708, ISO 14230-4, ISO 15765-4 and ISO 9141-2, ISO 27145-4 and Euro6). Fits for Cummins, Paccar, Detroit, Caterpillar, Freightliner, International, Peterbilt, Ford Heavy Truck, Class 4-Class 8 trucks, etc. It also supports engine diagnosis on most cars, minivans, light trucks and pickups
【 Full System Diagnostic】HD601 Diesel Scanner supports all system scans of heavy trucks compliant with standard protocols SAE J1939 & J1708, such as Engine, ABS, Transmission, Braking System, ESP, EPS, Fuel System, etc, It is a great scan tool for Cummins, Caterpillar, Detroit, Caterpillar, Maxxforce, Bendix,Wabash, Wabaco, Haldex, Allison, Eaton heavy trucks, With this truck tool, you can get deep analysis data about the system and do some repairs by yourself, saving much time and money. Note: Only heavy truck vehicles that comply with the above protocol can diagnose the entire system
【Enhanced Diesel OBD Scanner】The HD601 Diesel OBD Scanner offers unparalleled diagnostic capabilities for heavy-duty trucks. Beyond code reading, clearing, and live data display, it retrieves vehicle information, freeze frames, and DTCs. With 6, 9, and 16 pin cables, it ensures compatibility with various engines. This scanner's real-world testing prowess ensures comprehensive support for a wide array of heavy-duty truck engines, making it an indispensable tool for truck diagnostics
【DTC Library】+【Life Time Free Update】The built-in DTC library allows you to retrieve the codes directly without searching for the definition in the book. Whether you are a professional mechanic or a DIY car owner, HD601 diesel scanner explains the existing problem, makes it easier for you to understand code definitions and helps you locate vehicle faults. Note: This device cannot directly solve the fault. Plus, you get a lifetime free internet updates, so you always have the latest software for diagnostics in English and Spanish languages.
【Friendly Design, Easy of Use】This scanner is plug and play, simple and convenient, and very friendly for beginners. With improved buttons for easy menu navigation. The excellent 2.8 inch LCD color screen makes it easy to view the displayed results and gives you a better overview of your car's problem areas and the identified codes. In addition, the processor is super-fast and responds without lagging, providing maximum comfort and efficiency in diagnostic and service work

SaleBestseller No. 3

NEXAS Heavy Duty Truck Scanner NL102 Full System Diesel Truck Scan Tool for Cummins, Isuzu, Freightliner, Caterpillar, Detroit, Peterbilt, 2-in-1 Code Reader Read & Clear Fault Codes for Truck & Car

Why NEXAS NL102 Truck Scan Tool? The NL102 outshines other truck scanner with its extensive diagnostic features. It offers full system diagnostics for major trucks meeting standard protocols, along with complete OBD2 functionality. Beyond read fault codes, clear codes and live data display, it enables vehicle info retrieval, freeze frame capture, and DTC lookup. Equipped with 6-pin, 9-pin, 16-pin connectors, it ensures broad truck compatibility. Plus, enjoy lifetime free updates in English, Spanish, and French, keeping your diagnostic scanner software current.
Wide Compatibility - Friendly Reminder: To avoid compatibility issues, please confirm with us via Amazon Messages before purchasing. This heavy duty truck scanner is compatible with all heavy-duty trucks and semi that adhere to standard protocols (J1587, J1939, J1708). It covers a wide range of vehicle models, including Cummins, Detroit, Caterpillar, Freightliner, International, Kenworth, John Deere, Peterbilt, Sterling, Mack, Paccar, Western Star, Mercedes-Benz, Volvo, Scania, MAN, Renault, ERF, Foden, Seddon-Atkinson, Iveco, DAF, SISU, STEYR, ISUZU etc. Equipped with 6-pin, 9-pin, and 16-pin connectors for versatile device compatibility, ensuring stable plug-and-play connections.
Save Hundreds of Money for All Heavy Duty Trucks – This diesel diagnostic scanner supports accurate full-system scans for all heavy-duty trucks that comply with standard protocols (J1587, J1939, and J1708). It can read and clear trouble codes across a range of vehicle systems, including the engine, transmission, instrument panel, drivetrain, brake system, suspension, ABS, ESP, EPS, fuel system, etc. The truck scanner communicates directly with your truck's computer to provide real-time data stream analysis, letting you pinpoint issues with precision. This cuts down on waste from unnecessary part replacements, saving you time and hundreds or even thousands of dollars.
All OBD2 Functions + Battery Health Monitoring – Unlike many obd2 scanners on the market that only cover partial OBD2 features, ours gives you full OBD2 capability: read & clear codes, live data, freeze frame data, I/M readiness checks, EVAP tests, on-board monitor, O2 sensor tests, vehicle info, and DTC lookup. That means more detailed insights for pros and DIYers alike. The NL102 isn't just a code scanner – it's a battery saver. Regularly check your car's battery health, and catch issues before it dies completely. No more unexpected no-starts in the driveway or on the road. It diagnoses battery condition accurately, helping you avoid costly last-minute repairs.
Plug and Play & One-click for DTC: NEXAS diesel scanner is user-friendly. It comes with an intuitive screen and easy-to-understand interface, making it accessible even for non-professionals to get started. And the built-in DTC library in the code reader allows you to directly retrieve codes without searching for definitions in books, making it easier to understand the code definitions and solve problems more quickly.

This product presentation was made with AAWP plugin.

Last update on 2026-05-12 / Affiliate links / Images from Amazon Product Advertising API

Buffer Email Facebook Flipboard Hacker News LinkedIn Messenger Mix Pinterest Print Reddit SMS Telegram Tumblr X VK WhatsApp Line Xing Threads Bluesky Copy Mastodon Nextdoor