AutoCodes – GMC – P1B8B GMC

P1B8B GMC Code - Hybrid/Electric Vehicle Battery 56 Circuit Low 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: P1B8B GMC indicates Hybrid/Electric Vehicle Battery 56 Circuit Low 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 741

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 P1B8B 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 P1B8B GMC - Hybrid/Electric Vehicle Battery 56 Circuit Low Voltage - AutoCodes.com — P1B8B GMC Code - Hybrid/Electric Vehicle Battery 56 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P1B8B GMC?

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

How to Fix the DTC P1B8B 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 P1B8B 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 P1B8B GMC Code

1. What does the OBDII code P1B8B mean on a GMC vehicle?

The P1B8B code indicates a low voltage issue in the Hybrid/Electric Vehicle Battery 56 Circuit, which is part of the battery monitoring system.

2. What are the common symptoms of the P1B8B code?

Symptoms can include reduced hybrid or electric performance, warning lights on the dashboard, and possible difficulty starting the vehicle.

3. What causes the P1B8B code to appear?

The code can be triggered by a faulty battery cell, damaged wiring, a malfunctioning battery management module, or corrosion in the circuit connections.

4. Can I drive my GMC with a P1B8B code?

Itâ€™s not recommended, as the issue may lead to reduced performance or further damage to the hybrid/electric battery system.

5. How do I diagnose the P1B8B code?

Diagnosis involves scanning the vehicle for additional codes, inspecting the wiring and connections, and testing the battery cells and battery management module.

6. What repairs are commonly needed to fix the P1B8B code?

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

7. How much does it cost to fix the P1B8B code on a GMC vehicle?

The cost varies widely depending on the exact issue, but repairs can range from a few hundred dollars for wiring fixes to several thousand dollars for battery module replacement.

8. Can a weak 12V battery cause the P1B8B code?

While the 12V battery is separate from the hybrid battery, a weak 12V battery can sometimes cause communication or diagnostic errors that may trigger related codes.

9. What tools are needed to troubleshoot the P1B8B code?

Youâ€™ll need an advanced OBDII scanner capable of reading hybrid/electric system codes, a multimeter for voltage testing, and manufacturer-specific diagnostic guides.

10. Is the P1B8B code covered under GMCâ€™s warranty?

Hybrid/electric system components are often covered under an extended warranty, so check your vehicleâ€™s warranty terms to see if repairs are eligible.