Engine-Codes - Gmc - P0C77 GMC

P0C77 GMC Code - Hybrid Battery System Precharge Time Too Short

- Code Popularity: 795 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
Table of contents

|What are the Possible Causes of the P0C77 GMC Code?

  • 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 P0C77 GMC Code?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

|What is the cost to diagnose the P0C77 GMC code?

Labor: 1.0

The cost to diagnose the P0C77 GMC code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

|What are P0C77 GMC code possible symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

|What Does the P0C77 GMC Code Mean?

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.

Hybrid Battery System Precharge Time Too Short

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