AutoCodes – GMC – P1B21 GMC

P1B21 GMC Code - Hybrid/Electric Vehicle Battery 30 Circuit High Voltage

Quick Answer

The Hybrid/Electric Vehicle battery pack contains 288 cells. Common causes include Faulty Hybrid/Electric Vehicle Battery Pack, Faulty Hybrid/Electric Vehicle Battery Interface Control Module. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1B21 GMC indicates Hybrid/Electric Vehicle Battery 30 Circuit High Voltage.
Common causes: Common causes include Faulty Hybrid/Electric Vehicle Battery Pack, Faulty Hybrid/Electric Vehicle Battery Interface Control Module.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 965

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 08, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1B21 GMC Description

The Hybrid/Electric Vehicle battery pack contains 288 cells. Groups of three cells are welded together in parallel. There are a total of 96 cell groups in the hybrid/EV battery pack assembly. These cell groups are electrically connected in-series. Each individual cell group is rated at 3.7 V, for a nominal system voltage of 355 V direct current. The battery cells are also grouped together into three sections. The first 90 cells/30 cell groups make up battery section one. This section is adjacent to the cowl and contains batteries 67 through to 96. Battery section two is located behind section one. It is made up of 72 cells/24 cell groups and contains batteries 43 through to 66. The transverse battery section is section number three, it is made up of the remaining 126 cells/42 cell groups and contains batteries 1 through to 42. The three battery sections are individually serviceable components.
The battery energy control module monitors the voltage of the 96 battery cell groups through the four hybrid/EV battery interface control modules. Voltage sense circuits are attached to each individual cell group, and these sense circuits terminate at a connector located on the top surface of the battery section. A serviceable auxiliary battery wiring harness joins this connector to a hybrid/EV battery interface control module, also located on the top surface of the battery section. The hybrid/EV battery interface control module encodes the voltage reading and transmits it to the battery energy control module through the battery control harness. There is one hybrid/EV battery interface control module located on battery sections one and two, and two hybrid/EV battery interface control modules associated with battery section three. The hybrid/EV battery interface control module, battery energy control module wiring harness, auxiliary battery wiring harness, and battery energy control module are all considered serviceable components.
The battery energy control module will determine when a fault condition is present. Diagnostics and system status are communicated from the battery energy control module to hybrid/EV powertrain control module 2 through serial data. The hybrid/EV powertrain control module 2 is the host controller for diagnostic trouble code information.

OBDII Code P1B21 GMC - Hybrid/Electric Vehicle Battery 30 Circuit High Voltage - AutoCodes.com — P1B21 GMC Code - Hybrid/Electric Vehicle Battery 30 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P1B21 GMC?

Faulty Hybrid/Electric Vehicle Battery Pack
Faulty Hybrid/Electric Vehicle Battery Interface Control Module

How to Fix the DTC P1B21 GMC?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1B21 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1B21 GMC Code

1. What are the common symptoms of OBDII code P1B21 GMC related to the Hybrid/Electric Vehicle Battery 30 Circuit High Voltage issue?

- Common symptoms include reduced fuel efficiency, loss of power, illuminated warning lights on the dashboard, and difficulty starting the vehicle.

2. What are the possible causes of the OBDII code P1B21 GMC indicating the Hybrid/Electric Vehicle Battery 30 Circuit High Voltage problem?

- The code may be triggered by issues such as a faulty high voltage battery, damaged wiring or connectors, a malfunctioning battery management system, or software glitches.

3. How can I diagnose the OBDII code P1B21 GMC for the Hybrid/Electric Vehicle Battery 30 Circuit High Voltage fault?

- Diagnosis typically involves using an OBDII scanner to retrieve the specific code, inspecting the high voltage battery and related components for physical damage, and conducting electrical tests to pinpoint the exact issue.

4. Are there any safety precautions to consider when dealing with the Hybrid/Electric Vehicle Battery 30 Circuit High Voltage issue?

- Yes, it is crucial to follow proper safety procedures when working on high voltage systems. Ensure the vehicle is powered off, wear appropriate personal protective equipment, and refer to the manufacturer's guidelines for handling high voltage components.

5. Can I repair the OBDII code P1B21 GMC related to the Hybrid/Electric Vehicle Battery 30 Circuit High Voltage problem myself?

- While some basic troubleshooting and inspections can be done by DIY enthusiasts, it is recommended to seek assistance from a qualified technician or dealership due to the complexity and safety risks associated with high voltage systems.

6. What are some general tips for preventing the recurrence of the OBDII code P1B21 GMC Hybrid/Electric Vehicle Battery 30 Circuit High Voltage issue?

- Regular maintenance of the high voltage battery system, avoiding overcharging or deep discharging the battery, and promptly addressing any warning lights or unusual symptoms can help prevent the code from reoccurring.

7. How urgent is it to address the OBDII code P1B21 GMC Hybrid/Electric Vehicle Battery 30 Circuit High Voltage problem?

- It is important to address the issue promptly to prevent further damage to the high voltage system and ensure the safe operation of the vehicle. Ignoring the problem can lead to more severe issues and potential safety hazards.

8. Can resetting the OBDII code P1B21 GMC related to the Hybrid/Electric Vehicle Battery 30 Circuit High Voltage issue temporarily resolve the problem?

- Resetting the code may temporarily clear the warning light, but it will not fix the underlying issue causing the fault. It is recommended to diagnose and repair the root cause of the problem to prevent future occurrences.

9. Is the OBDII code P1B21 GMC related to the Hybrid/Electric Vehicle Battery 30 Circuit High Voltage issue covered under any warranties?

- Depending on the vehicle's warranty coverage and the specific circumstances, the repair for this code may be covered under the manufacturer's warranty for the high voltage components. It is advisable to check with the dealership or warranty provider for clarification.

10. How can I find a qualified mechanic or dealership to help diagnose and repair the OBDII code P1B21 GMC Hybrid/Electric Vehicle Battery 30 Circuit High Voltage issue?

- You can search for certified hybrid or electric vehicle technicians at authorized dealerships, specialized repair shops, or service centers that have experience working with high voltage systems. Additionally, reading reviews and asking for recommendations from other hybrid/electric vehicle owners can help in finding a reliable mechanic.