AutoCodes – GMC – P1E78 GMC

P1E78 GMC Code - Hybrid/Electric Vehicle Battery 77 Circuit

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: P1E78 GMC indicates Hybrid/Electric Vehicle Battery 77 Circuit.
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 830

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 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1E78 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 P1E78 GMC - Hybrid/Electric Vehicle Battery 77 Circuit - AutoCodes.com — P1E78 GMC Code - Hybrid/Electric Vehicle Battery 77 Circuit

What does this mean?

What are the Possible Causes of the DTC P1E78 GMC?

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

How to Fix the DTC P1E78 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 P1E78 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 P1E78 GMC Code

1. What are common symptoms of OBDII code P1E78 GMC related to the Hybrid/Electric Vehicle Battery 77 Circuit?

- Common symptoms include reduced hybrid system performance, decreased fuel efficiency, and potential inability to start the vehicle.

2. What are the possible causes of OBDII code P1E78 GMC indicating an issue with the Hybrid/Electric Vehicle Battery 77 Circuit?

- Possible causes include a faulty battery pack, damaged battery cell/module, issues with the battery management system, or wiring/connectivity problems.

3. How can I diagnose the source of OBDII code P1E78 GMC on my GMC hybrid/electric vehicle?

- Diagnosis typically involves using a scan tool to read the specific fault codes, testing the battery pack and individual cells/modules, and inspecting the battery circuitry for any visible issues.

4. Is it safe to continue driving with OBDII code P1E78 GMC present in a GMC hybrid/electric vehicle?

- It is not recommended to continue driving with this code as it can lead to further damage to the hybrid system and potentially cause safety concerns. It's best to address the issue promptly.

5. Can I repair OBDII code P1E78 GMC related to the Hybrid/Electric Vehicle Battery 77 Circuit on my own?

- While some basic troubleshooting like checking for loose connections or damaged wiring can be done by DIY enthusiasts, diagnosing and repairing complex hybrid system issues is best left to trained professionals.

6. Are there any specific maintenance tips to prevent OBDII code P1E78 GMC from occurring in a GMC hybrid/electric vehicle?

- Regularly inspecting the battery pack, following manufacturer-recommended maintenance schedules, and avoiding extreme temperature conditions can help prevent issues with the Hybrid/Electric Vehicle Battery 77 Circuit.

7. How much does it typically cost to repair OBDII code P1E78 GMC associated with the Hybrid/Electric Vehicle Battery 77 Circuit?

- Repair costs can vary depending on the exact cause of the issue, but they can range from a few hundred to over a thousand dollars, especially if battery replacement or major repairs are needed.

8. Can resetting the OBDII system clear OBDII code P1E78 GMC on a GMC hybrid/electric vehicle?

- Resetting the system may temporarily clear the code, but if the underlying issue is not addressed, the code is likely to reappear once the vehicle is driven again.

9. How long does it take to repair OBDII code P1E78 GMC related to the Hybrid/Electric Vehicle Battery 77 Circuit?

- The repair time can vary depending on the complexity of the issue and the availability of parts, but it may take anywhere from a few hours to a day or more to diagnose and fix the problem.

10. Can OBDII code P1E78 GMC be caused by a simple loose connection in the Hybrid/Electric Vehicle Battery 77 Circuit?

- Yes, a loose or corroded connection in the battery circuitry can sometimes trigger this code, making it important to check for such issues before pursuing more extensive repairs.