AutoCodes – GMC – P1B79 GMC

P1B79 GMC Code - Hybrid/Electric Vehicle Battery 50 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: P1B79 GMC indicates Hybrid/Electric Vehicle Battery 50 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 869

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 P1B79 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 P1B79 GMC - Hybrid/Electric Vehicle Battery 50 Circuit Low Voltage - AutoCodes.com — P1B79 GMC Code - Hybrid/Electric Vehicle Battery 50 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P1B79 GMC?

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

How to Fix the DTC P1B79 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 P1B79 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 P1B79 GMC Code

1. What does the OBDII code P1B79 mean for GMC vehicles?

P1B79 indicates a low voltage issue in the Hybrid/Electric Vehicle Battery 50 Circuit, which is part of the battery monitoring or control system.

2. What are the common symptoms of the P1B79 code?

Symptoms include reduced fuel efficiency, a hybrid system warning light, limited electric mode functionality, or a lack of power from the hybrid battery.

3. What causes the P1B79 code to appear?

Common causes include a faulty battery cell, damaged wiring or connectors in the circuit, a defective battery sensor module, or issues with the hybrid control module.

4. Can I continue driving with the P1B79 code?

Driving with this code is possible but not recommended, as it may lead to further damage to the hybrid system and reduced performance.

5. How is the P1B79 code diagnosed?

A technician will use a scan tool to read the code, inspect the hybrid battery and its circuits, check wiring and connectors, and perform voltage tests on the affected circuit.

6. What repairs can fix the P1B79 code?

Repairs may include replacing damaged wiring, repairing or replacing the hybrid battery, fixing or replacing the battery sensor module, or updating the hybrid control module software.

7. Is the P1B79 code covered under warranty?

Warranty coverage depends on the vehicle's age and mileage; hybrid battery components often have extended warranties, so itâ€™s best to check with your dealership.

8. Can a weak 12-volt battery cause the P1B79 code?

While a weak 12-volt battery can cause some hybrid system issues, the P1B79 code specifically relates to the high-voltage hybrid battery circuit.

9. How much does it cost to fix the P1B79 code?

Repair costs vary widely, ranging from $200 for minor wiring repairs to over $3,000 if the hybrid battery needs replacement.

10. Can I reset the P1B79 code without repairs?

While clearing the code with a scan tool may temporarily remove it, the underlying issue must be fixed to prevent the code from returning and ensure proper vehicle function.