AutoCodes – Buick – P1B85 Buick

P1B85 Buick Code - Hybrid/Electric Vehicle Battery 54 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: P1B85 Buick indicates Hybrid/Electric Vehicle Battery 54 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 829

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 P1B85 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 P1B85 Buick - Hybrid/Electric Vehicle Battery 54 Circuit Low Voltage - AutoCodes.com — P1B85 Buick Code - Hybrid/Electric Vehicle Battery 54 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P1B85 Buick?

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

How to Fix the DTC P1B85 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 P1B85 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 P1B85 Buick Code

1. What does the OBDII code P1B85 mean on a Buick?

P1B85 indicates a low voltage issue in the Hybrid/Electric Vehicle Battery 54 circuit, which is specific to the hybrid or electric powertrain system.

2. What are the common symptoms of code P1B85 on a Buick?

Symptoms may include the check engine light or hybrid system warning light, reduced fuel efficiency, limited electric power, or decreased overall performance.

3. What causes the P1B85 code to appear on a Buick?

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

4. Can I drive my Buick with the P1B85 code?

Itâ€™s not recommended to drive with this code, as it could lead to reduced performance or potential damage to the hybrid battery system.

5. How do I diagnose the P1B85 code on my Buick?

Diagnosis involves scanning for other related codes, visually inspecting wiring and connectors, and testing the voltage of the affected battery circuit.

6. What repairs are needed to fix the P1B85 code on a Buick?

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

7. Can a weak 12-volt battery trigger the P1B85 code on a Buick?

While unlikely, a weak or failing 12-volt battery can sometimes cause related hybrid system issues. Itâ€™s worth testing the 12-volt battery as part of the diagnosis.

8. How much does it cost to fix the P1B85 code on a Buick?

Repair costs vary depending on the issue, but replacing a hybrid battery module can cost between $1,000 and $4,000, while wiring repairs are typically less expensive.

9. Can I clear the P1B85 code without fixing the issue?

Clearing the code without addressing the underlying problem will only temporarily turn off the warning light, and the code will likely return.

10. Does the P1B85 code affect all Buick hybrid models?

This code is specific to hybrid or electric Buick models equipped with a battery system that monitors individual circuits, but it may not apply to all models. Always confirm applicability with your vehicleâ€™s manual.