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P1639 GMC Code - PCM 5 Volt Reference Voltage Circuit Condition

Quick Answer

The P1639 diagnostic trouble code for GMC vehicles indicates a problem with the PCM (Powertrain Control Module) 5 Volt Reference Voltage Circuit. Common causes include Damaged wiring or connectors in the 5-volt reference voltage circuit, Faulty sensor or component drawing excess current, PCM malfunction. 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
P1639 GMC indicates PCM 5 Volt Reference Voltage Circuit Condition.
Common causes
Common causes include Damaged wiring or connectors in the 5-volt reference voltage circuit, Faulty sensor or component drawing excess current, PCM malfunction.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P1639 GMC Description

The P1639 diagnostic trouble code for GMC vehicles indicates a problem with the PCM (Powertrain Control Module) 5 Volt Reference Voltage Circuit. The PCM is a crucial component of the vehicle's engine control system, responsible for monitoring and controlling various functions to ensure optimal performance and efficiency. The 5-volt reference voltage circuit is essential for providing power to sensors and other components that require a constant voltage supply to function correctly.

OBDII Code P1639 GMC - PCM 5 Volt Reference Voltage Circuit Condition
P1639 GMC Code - PCM 5 Volt Reference Voltage Circuit Condition

Common Causes of P1639 GMC

  1. Damaged wiring or connectors in the 5-volt reference voltage circuit
  2. Faulty sensor or component drawing excess current
  3. PCM malfunction
  4. Corrosion or moisture affecting electrical connections
  5. Short circuit in the wiring harness

Symptoms of P1639 GMC

  1. Engine misfires or rough idling
  2. Reduced fuel efficiency
  3. Check Engine Light illuminated
  4. Poor acceleration or hesitation
  5. Inconsistent or erratic engine performance

How to Fix P1639 GMC

  1. Begin by conducting a thorough inspection of the wiring, connectors, and components related to the 5-volt reference voltage circuit.
  2. Use a multimeter to test the voltage output at various points in the circuit to identify any irregularities.
  3. Replace any damaged wiring, connectors, or components as needed.
  4. Clear the diagnostic trouble codes from the PCM memory and test drive the vehicle to ensure the issue has been resolved.
  5. If the problem persists, consult a professional mechanic for further diagnosis and potential PCM replacement.

Cost to Fix P1639 GMC

The typical repair costs for addressing a PCM 5 Volt Reference Voltage Circuit Condition can vary depending on the specific cause of the issue and the extent of the repairs needed. On average, the cost for parts and labor can range from $200 to $500. However, it's essential to note that prices can fluctuate based on factors such as location, vehicle make and model, and the mechanic's hourly rates. It's advisable to obtain quotes from multiple auto repair shops to compare prices and ensure a fair estimate for the repair.

When is the Code Detected?

If the voltage is out of tolerance, the Powertrain Control Module (PCM) will set DTC P1639.

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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 P1639 GMC Code

1. What are the common symptoms of OBDII code P1639 GMC?

- Common symptoms include engine stalling, rough idling, poor acceleration, and issues with the vehicle's electrical systems.

2. What does the OBDII code P1639 GMC indicate about the PCM 5 volt reference voltage circuit?

- The code indicates a problem with the PCM's ability to regulate the 5-volt reference voltage required for various sensors and components.

3. What are the possible causes of the PCM 5 volt reference voltage circuit condition error?

- Potential causes include a faulty PCM, damaged wiring harness, short circuits, loose connections, or issues with the 5-volt reference voltage regulator.

4. How can I diagnose the PCM 5 volt reference voltage circuit condition error?

- Diagnosis typically involves using a multimeter to check the voltage output of the PCM and inspecting the wiring and connectors for any signs of damage or corrosion.

5. Can driving with the OBDII code P1639 GMC cause further damage to the vehicle?

- Continuing to drive with this code may lead to further electrical issues or damage to the vehicle's sensors and components, so it is advisable to address the problem promptly.

6. How is the PCM 5 volt reference voltage circuit condition error typically repaired?

- Repair may involve replacing the PCM, repairing or replacing damaged wiring, addressing any short circuits, or fixing loose connections as needed.

7. Is it safe to clear the OBDII code P1639 GMC and continue driving the vehicle?

- Clearing the code may temporarily eliminate warning lights, but if the underlying issue is not resolved, it can lead to ongoing problems. It's recommended to diagnose and fix the root cause.

8. Can a DIY enthusiast without advanced automotive knowledge fix the PCM 5 volt reference voltage circuit error?

- While some basic troubleshooting steps can be taken, diagnosing and repairing this issue may require specialized tools and expertise, so it's advisable to seek professional help.

9. Are there any preventive measures to avoid encountering the PCM 5 volt reference voltage circuit condition error?

- Regular vehicle maintenance, including checking the wiring harness for wear and ensuring proper electrical connections, can help prevent issues related to the 5-volt reference voltage circuit.

10. How long does it typically take a mechanic to diagnose and repair the PCM 5 volt reference voltage circuit condition error?

- The time required for diagnosis and repair can vary depending on the specific cause of the issue, but it may take a few hours to a full day for a mechanic to properly address the problem.

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