AutoCodes – GMC – P1A89 GMC

P1A89 GMC Code - 42 Volt System Voltage Low

Quick Answer

The Accessory Power Module (APM) supplies the energy that flows between the high voltage, 300 volt, direct current (DC) and intermediate voltage, 42 volt, DC to support the Electric Power Steering (EPS). Common causes include Faulty Accessory Power Module (APM), Accessory Power Module (APM) harness is open or shorted, Accessory Power Module (APM) 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: P1A89 GMC indicates 42 Volt System Voltage Low.
Common causes: Common causes include Faulty Accessory Power Module (APM), Accessory Power Module (APM) harness is open or shorted, Accessory Power Module (APM) 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 981

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 23, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1A89 GMC Description

The Accessory Power Module (APM) supplies the energy that flows between the high voltage, 300 volt, direct current (DC) and intermediate voltage, 42 volt, DC to support the Electric Power Steering (EPS). The APM receives a 42 volt enable command from the Hybrid Powertrain Control Module (HPCM) over the high speed hybrid GMLAN communication circuit. 42 volt APM functions will run only when the 42 volt APM enable is active on the high speed hybrid GMLAN communication circuit.

OBDII Code P1A89 GMC - 42 Volt System Voltage Low - AutoCodes.com — P1A89 GMC Code - 42 Volt System Voltage Low

What does this mean?

What are the Possible Causes of the DTC P1A89 GMC?

Faulty Accessory Power Module (APM)
Accessory Power Module (APM) harness is open or shorted
Accessory Power Module (APM) circuit poor electrical connection

How to Fix the DTC P1A89 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 P1A89 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.

Need more information about the P1A89 GMC code?

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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 P1A89 GMC Code

1. What are the common symptoms of OBDII code P1A89 GMC (42 Volt System Voltage Low)?

The common symptoms of this code may include dimming lights, issues with electrical components, and difficulty starting the vehicle.

2. What are the possible causes of the OBDII code P1A89 GMC (42 Volt System Voltage Low)?

Possible causes of this code include a faulty hybrid battery, problems with the voltage regulator, damaged wiring, or issues with the alternator.

3. How can I diagnose the OBDII code P1A89 GMC (42 Volt System Voltage Low)?

Diagnosing this code typically involves using a scan tool to check for related trouble codes, testing the voltage of the hybrid battery, inspecting the wiring for damage, and ensuring proper connection of electrical components.

4. Can I continue driving with OBDII code P1A89 GMC (42 Volt System Voltage Low) present?

It's not recommended to continue driving with this code active, as it can lead to further electrical issues and potential damage to the vehicle's components.

5. How can I repair OBDII code P1A89 GMC (42 Volt System Voltage Low)?

Repairing this code may involve replacing the hybrid battery, repairing or replacing the voltage regulator, fixing damaged wiring, or addressing any issues with the alternator.

6. Will resetting the OBDII code P1A89 GMC (42 Volt System Voltage Low) make it go away permanently?

Resetting the code may temporarily clear it, but if the underlying issue is not addressed, the code is likely to return.

7. Are there any DIY tips for fixing OBDII code P1A89 GMC (42 Volt System Voltage Low)?

DIY tips may include checking and cleaning battery connections, inspecting wiring for visible damage, and ensuring the alternator is functioning properly.

8. How urgent is it to address OBDII code P1A89 GMC (42 Volt System Voltage Low)?

It's important to address this code promptly to prevent further damage to the vehicle's electrical system and ensure safe operation of the vehicle.

9. Can extreme weather conditions contribute to triggering OBDII code P1A89 GMC (42 Volt System Voltage Low)?

Yes, extreme temperatures can affect the performance of the hybrid battery and electrical components, potentially leading to the triggering of this code.

10. Is it necessary to visit a mechanic for OBDII code P1A89 GMC (42 Volt System Voltage Low) diagnosis and repair?

While some DIY checks can be done, it is recommended to visit a mechanic for a thorough diagnosis and proper repair of this code to ensure the issue is resolved correctly.