AutoCodes – GMC – P0C77 GMC

P0C77 GMC Code - Hybrid Battery System Precharge Time Too Short

Quick Answer

The drive motor generator battery control module is also referred to as the Battery Energy Control Module (BECM). Common causes include Faulty Drive Motor Generator Battery Assembly, Drive Motor Generator Battery Assembly harness is open or shorted, Drive Motor Generator Battery Assembly circuit poor electrical connection. 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: P0C77 GMC indicates Hybrid Battery System Precharge Time Too Short.
Common causes: Common causes include Faulty Drive Motor Generator Battery Assembly, Drive Motor Generator Battery Assembly harness is open or shorted, Drive Motor Generator Battery Assembly circuit poor electrical connection.
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 1,145

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 Feb 13, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0C77 GMC Description

The drive motor generator battery control module is also referred to as the Battery Energy Control Module (BECM). The drive motor generator battery control module will diagnose its own systems and determine when a fault condition is present. Diagnostics and system status is communicated from the drive motor generator battery control module to the Hybrid Powertrain Control Module (HPCM) through serial data. The hybrid powertrain control module is the host controller for Diagnostic Trouble Code (DTC) information.
1. The drive motor generator battery contains 3 high voltage contactors that allow the high voltage Direct Current (DC) batteries to be connected to the vehicle or safely contain the DC high voltage within the drive motor generator battery assembly. The three contactor/relays are a positive high voltage contactor, negative high voltage contactor, and the current limit relay.
2. The power-up sequence for the high voltage DC system occurs in the following order:
3. The drive motor generator battery control module performs a precharge test, by closing both the negative contactor and current limit relay. Because the current limit relay routes the high voltage current through a current limit resistor, the hybrid battery terminal voltage should increase at a steady, predictable rate.
When the drive motor generator battery control module observes that hybrid battery terminal voltage and hybrid battery calculated voltage are at about the same voltage, the motor generator battery control module closes the positive contactor.
With both the negative and positive contactors closed, the drive motor generator battery control module opens the current limit relay.

OBDII Code P0C77 GMC - Hybrid Battery System Precharge Time Too Short - AutoCodes.com — P0C77 GMC Code - Hybrid Battery System Precharge Time Too Short

What does this mean?

What are the Possible Causes of the DTC P0C77 GMC?

Faulty Drive Motor Generator Battery Assembly
Drive Motor Generator Battery Assembly harness is open or shorted
Drive Motor Generator Battery Assembly circuit poor electrical connection

How to Fix the DTC P0C77 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 P0C77 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 P0C77 GMC Code

1. What are the common symptoms of OBDII code P0C77 in a GMC vehicle?

When the OBDII code P0C77 is triggered in a GMC vehicle, common symptoms may include reduced fuel efficiency, loss of power, and the illumination of the check engine light.

2. What is the main cause of OBDII code P0C77 in a GMC vehicle?

The main cause of OBDII code P0C77 in a GMC vehicle is typically related to a malfunction in the hybrid battery system precharge time being too short.

3. How can I diagnose OBDII code P0C77 in my GMC vehicle?

Diagnosing OBDII code P0C77 in your GMC vehicle requires using an OBDII scanner to retrieve the specific fault code and then conducting further testing to pinpoint the exact cause, which may involve inspecting the hybrid battery system components.

4. Can I drive my GMC vehicle with OBDII code P0C77?

It is not recommended to drive your GMC vehicle with OBDII code P0C77 present, as it can lead to further damage to the hybrid battery system and potentially affect the vehicle's performance and safety.

5. How can I repair OBDII code P0C77 in my GMC vehicle?

Repairing OBDII code P0C77 in a GMC vehicle may involve inspecting and repairing or replacing components of the hybrid battery system, such as the precharge circuit or related wiring, to ensure proper precharge time.

6. Is it safe to reset OBDII code P0C77 in my GMC vehicle?

Resetting OBDII code P0C77 in your GMC vehicle may temporarily turn off the check engine light, but it will not address the underlying issue causing the code. It is important to diagnose and repair the problem to prevent future occurrences.

7. How much does it cost to fix OBDII code P0C77 in a GMC vehicle?

The cost to fix OBDII code P0C77 in a GMC vehicle can vary depending on the specific cause of the issue and the extent of repairs needed. It is recommended to consult with a professional mechanic for an accurate diagnosis and cost estimate.

8. Can a DIY enthusiast repair OBDII code P0C77 in a GMC vehicle?

Repairing OBDII code P0C77 in a GMC vehicle may require specialized knowledge and tools related to hybrid battery systems. It is recommended to seek assistance from a qualified mechanic or hybrid vehicle technician for proper diagnosis and repair.

9. Will OBDII code P0C77 affect the overall performance of my GMC vehicle?

Yes, OBDII code P0C77 can affect the overall performance of your GMC vehicle, leading to reduced fuel efficiency, power loss, and potential drivability issues if left unresolved.

10. How often does OBDII code P0C77 occur in GMC vehicles?

OBDII code P0C77 related to the hybrid battery system precharge time being too short is a relatively uncommon issue in GMC vehicles, but it can occur due to various factors affecting the hybrid system's operation.