AutoCodes – Cadillac – P1B77 Cadillac

P1B77 Cadillac 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 Cadillac 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 1,012

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 Cadillac 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 Cadillac - Hybrid/Electric Vehicle Battery 49 Circuit High Voltage - AutoCodes.com — P1B77 Cadillac Code - Hybrid/Electric Vehicle Battery 49 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P1B77 Cadillac?

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

How to Fix the DTC P1B77 Cadillac?

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 Cadillac 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 Cadillac Code

What does the OBDII code P1B77 mean on a Cadillac?

The P1B77 code indicates a high-voltage issue in the Hybrid/Electric Vehicle Battery 49 Circuit, typically related to one of the battery modules or its associated connections.

What are the common symptoms of the P1B77 code?

Symptoms may include an illuminated check engine light, reduced hybrid performance, limited battery charge/discharge capability, or the vehicle entering limp mode.

What causes the P1B77 code in a Cadillac?

Common causes include a faulty battery module, damaged wiring or connectors in the high-voltage battery circuit, or a malfunctioning battery management system.

Can I drive my Cadillac with the P1B77 code?

It is not recommended to drive with this code, as it may result in reduced performance or further damage to the hybrid/electric system.

How is the P1B77 code diagnosed?

A technician will use a scan tool to confirm the code, inspect the high-voltage battery and its wiring for damage, and perform voltage tests to isolate the specific issue.

What repairs are typically needed for the P1B77 code?

Repairs may include replacing a faulty battery module, repairing damaged wiring or connectors, or reprogramming the battery management system.

How much does it cost to fix the P1B77 code?

Repair costs vary depending on the issue, but replacing a battery module can range from $1,000 to $3,000, while wiring repairs may cost a few hundred dollars.

Can the P1B77 code be cleared without repairs?

Clearing the code without addressing the underlying issue may cause it to return and could lead to further damage to the hybrid system.

What tools are needed to troubleshoot the P1B77 code?

A professional-grade OBDII scan tool, a multimeter for voltage testing, and access to the vehicleâ€™s service manual are typically required.

Is the P1B77 code covered under warranty?

If your Cadillac is under warranty or subject to a hybrid system-specific warranty, repairs for this code may be covered. Check with your dealership for details.