AutoCodes – Buick – P1B77 Buick

P1B77 Buick Code - Hybrid/Electric Vehicle Battery 49 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: P1B77 Buick indicates Hybrid/Electric Vehicle Battery 49 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 1,170

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 12, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1B77 Buick 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 P1B77 Buick - Hybrid/Electric Vehicle Battery 49 Circuit High Voltage - AutoCodes.com — P1B77 Buick Code - Hybrid/Electric Vehicle Battery 49 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P1B77 Buick?

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

How to Fix the DTC P1B77 Buick?

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 P1B77 Buick 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 P1B77 Buick Code

What does the OBDII code P1B77 mean for a Buick?

Code P1B77 indicates a high voltage issue in the Hybrid/Electric Vehicle Battery 49 Circuit, meaning an abnormal reading or fault has been detected in this specific circuit.

What are the symptoms of code P1B77 in a Buick?

Common symptoms include warning lights on the dashboard, reduced hybrid or electric system performance, and possible loss of fuel efficiency.

What causes code P1B77 to appear in a Buick?

This code can be caused by damaged wiring or connectors, a malfunctioning hybrid battery module, or issues with the battery management system.

Can code P1B77 lead to drivability problems?

Yes, it may cause limited power, reduced acceleration, or difficulty starting the vehicle if the hybrid or electric system is impaired.

How is code P1B77 diagnosed in a Buick?

Technicians use a scan tool to evaluate the code and inspect the Hybrid/Electric Vehicle Battery circuit for damaged wiring, loose connections, or faulty components.

Can I drive my Buick with code P1B77?

While the vehicle may still be drivable, ignoring the code could lead to further damage or reduced hybrid system efficiency, so itâ€™s best to address it promptly.

How do I fix code P1B77 in a Buick?

Repairs may involve checking and repairing wiring, replacing damaged connectors, or replacing the affected hybrid battery module or components.

What tools are needed to repair code P1B77?

A diagnostic scan tool and a multimeter are typically required to test the battery circuit and identify the source of the fault.

How much does it cost to fix code P1B77 in a Buick?

The repair cost can vary depending on whether itâ€™s just wiring or connector repairs or if the hybrid battery module needs replacement, with costs ranging from $200 to several thousand dollars.

Can a weak 12V battery cause code P1B77?

A weak or failing 12V auxiliary battery can sometimes contribute to hybrid system faults, so itâ€™s worth checking its condition as part of the diagnosis.