AutoCodes – Generic – P1A20

P1A20 Code - Hybrid Battery System Precharge Time Too Long

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: P1A20 indicates Hybrid Battery System Precharge Time Too Long.
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 7,173

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 15, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1A20 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 P1A20 - Hybrid Battery System Precharge Time Too Long - AutoCodes.com — P1A20 Code - Hybrid Battery System Precharge Time Too Long

What does this mean?

What are the Possible Causes of the DTC P1A20?

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 P1A20?

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 P1A20 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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Information for Specific Makes

P1A20 Buick — Hybrid Battery System Precharge Time Too Long
P1A20 Cadillac — Hybrid Battery System Precharge Time Too Long
P1A20 Chevrolet — Hybrid Battery System Precharge Time Too Long
P1A20 GMC — Hybrid Battery System Precharge Time Too Long

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 P1A20 Code

1. What are the common symptoms of OBDII code P1A20 (Hybrid Battery System Precharge Time Too Long)?

The common symptoms include the hybrid system warning light illuminating on the dashboard, decreased fuel efficiency, and potential difficulty starting the vehicle.

2. What are the possible causes of OBDII code P1A20?

Possible causes of this code include issues with the hybrid battery, a malfunctioning precharge relay, faulty wiring or connections in the hybrid system, or software glitches in the hybrid control module.

3. How can I diagnose the cause of OBDII code P1A20?

Diagnosing this code may require using a diagnostic scanner to retrieve specific trouble codes from the vehicle's computer system, as well as conducting tests on the hybrid battery, precharge relay, and related components to pinpoint the issue.

4. Can I continue driving my vehicle with OBDII code P1A20 present?

It is not recommended to continue driving the vehicle with this code present, as it can lead to further damage to the hybrid system and potentially result in safety hazards. It is best to address the issue promptly.

5. What are some repair tips for fixing OBDII code P1A20?

Repair tips may include checking and repairing any damaged wiring or connections in the hybrid system, replacing the precharge relay if faulty, testing and potentially replacing the hybrid battery if necessary, and ensuring all software updates are performed.

6. How much does it typically cost to repair OBDII code P1A20?

The cost of repairs for this code can vary depending on the specific cause of the issue and the extent of the repairs needed. Costs may range from a few hundred dollars for simple fixes to over a thousand dollars for more complex issues like hybrid battery replacement.

7. Can OBDII code P1A20 be reset without repairing the underlying issue?

While the code can be cleared using a diagnostic scanner, it is crucial to address the underlying problem causing the code to prevent it from reoccurring and potentially causing further damage to the vehicle.

8. Are there any preventive measures to avoid OBDII code P1A20 in the future?

Regular maintenance of the hybrid system, including checking and maintaining the hybrid battery, ensuring proper connections and wiring integrity, and staying up to date on software updates, can help prevent issues that may trigger this code.

9. Is it safe to attempt DIY repairs for OBDII code P1A20?

DIY repairs for this code may be possible for experienced individuals with knowledge of hybrid systems and the necessary tools. However, due to the complexity and safety considerations involved, it is generally recommended to seek professional assistance for proper diagnosis and repair.

10. How long does it typically take to repair OBDII code P1A20?

The repair time for this code can vary depending on the specific cause of the issue, the availability of parts, and the expertise of the technician. Simple repairs may be completed within a few hours, while more complex issues could take a day or more to resolve.