AutoCodes – Cadillac – P1E78 Cadillac

P1E78 Cadillac 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 Cadillac 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 848

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 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 P1E78 Cadillac - Hybrid/Electric Vehicle Battery 77 Circuit - AutoCodes.com — P1E78 Cadillac Code - Hybrid/Electric Vehicle Battery 77 Circuit

What does this mean?

What are the Possible Causes of the DTC P1E78 Cadillac?

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

How to Fix the DTC P1E78 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 P1E78 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 P1E78 Cadillac Code

1. What are the common symptoms of OBDII code P1E78 in a Cadillac Hybrid/Electric Vehicle?

- Common symptoms include poor fuel economy, reduced power, check engine light illumination, and potential issues with battery performance.

2. What could cause the Hybrid/Electric Vehicle Battery 77 Circuit issue in a Cadillac?

- The code P1E78 in a Cadillac Hybrid/Electric Vehicle may be triggered by a faulty high voltage battery, damaged wiring, or issues with the battery management system.

3. How serious is the P1E78 code in a Cadillac Hybrid/Electric Vehicle?

- The code P1E78 should be addressed promptly to prevent further damage to the hybrid/electric vehicle system and ensure optimal performance.

4. Can driving with the P1E78 code present cause further damage to the vehicle?

- Continuing to drive with the P1E78 code present can potentially lead to increased strain on the high voltage battery and other electrical components, resulting in more severe issues over time.

5. How can I diagnose the Hybrid/Electric Vehicle Battery 77 Circuit problem in my Cadillac?

- Proper diagnostic tools, such as an OBDII scanner, can help pinpoint the exact cause of the P1E78 code. Additionally, a thorough inspection of the high voltage battery system and related components is recommended.

6. Is it safe to attempt repairs for the P1E78 code on a Cadillac Hybrid/Electric Vehicle without professional help?

- Due to the high voltage nature of the system, it is recommended to seek professional assistance or consult a certified technician for repairs related to the Hybrid/Electric Vehicle Battery 77 Circuit issue.

7. Are there any common DIY fixes for the P1E78 code in a Cadillac Hybrid/Electric Vehicle?

- DIY fixes for the P1E78 code may include checking and tightening electrical connections, inspecting wiring for damage, and ensuring the high voltage battery is properly secured.

8. Can a faulty sensor trigger the P1E78 code in a Cadillac Hybrid/Electric Vehicle?

- Yes, a faulty sensor related to the high voltage battery system or battery management system can potentially trigger the P1E78 code in a Cadillac Hybrid/Electric Vehicle.

9. How much can I expect to pay for repairs related to the Hybrid/Electric Vehicle Battery 77 Circuit issue in a Cadillac?

- The cost of repairs for the P1E78 code can vary depending on the exact cause of the issue, but it is recommended to budget for potential high voltage system repairs or component replacements.

10. Will resetting the OBDII code temporarily resolve the P1E78 issue in a Cadillac Hybrid/Electric Vehicle?

- Resetting the OBDII code may temporarily clear the check engine light, but if the underlying issue causing the P1E78 code is not addressed, the problem is likely to reoccur.