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Engine-Codes – GMC – C0387 GMC

C0387 GMC Code - Unable to Complete Shift

Quick Answer

The C0387 GMC diagnostic trouble code refers to the vehicle's inability to complete a shift. Common causes include Low transmission fluid levels, Faulty transmission solenoid, Damaged transmission control module. 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
C0387 GMC indicates Unable to Complete Shift.
Common causes
Common causes include Low transmission fluid levels, Faulty transmission solenoid, Damaged transmission control module.
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 Aug 30, 2024
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Code C0387 GMC Description

The C0387 GMC diagnostic trouble code refers to the vehicle's inability to complete a shift. This code typically indicates a problem with the transmission system, specifically related to the shifting mechanism. When this code is triggered, it means that the vehicle's computer has detected an issue that is preventing the transmission from shifting properly. This can result in poor performance, erratic shifting, or in some cases, the vehicle may not be able to shift gears at all. It is crucial to address this issue promptly to prevent further damage to the transmission system.

OBDII Code C0387 GMC - Unable to Complete Shift
C0387 GMC Code - Unable to Complete Shift

Common Causes of C0387 GMC

  1. Low transmission fluid levels
  2. Faulty transmission solenoid
  3. Damaged transmission control module
  4. Malfunctioning shift linkage
  5. Internal transmission issues

Symptoms of C0387 GMC

  1. Difficulty shifting gears
  2. Delayed shifting
  3. Slipping gears
  4. Transmission not engaging
  5. Illumination of the check engine light

How to Fix C0387 GMC

  1. Check and top up transmission fluid levels
  2. Inspect and replace the transmission solenoid if faulty
  3. Test and possibly replace the transmission control module
  4. Inspect and repair any damaged shift linkage
  5. Conduct a thorough diagnostic of the transmission system to identify and address any internal issues

Cost to Fix C0387 GMC

The cost of repairing the C0387 GMC code can vary depending on the specific cause of the issue. On average, the repair costs for this type of transmission problem can range from $200 to $800, including parts and labor. It is important to note that diagnostic time and labor rates can vary, so it is advisable to obtain quotes from local auto repair shops for a more accurate estimate.

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Information for Specific GMC Models

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 C0387 GMC Code

1. What are the common symptoms of OBDII code C0387 GMC "Unable to Complete Shift"?

- Common symptoms include difficulty shifting gears, the transmission slipping, and the vehicle not engaging properly into gear.

2. What are some possible causes of OBDII code C0387 GMC "Unable to Complete Shift"?

- Possible causes include low transmission fluid levels, a faulty shift solenoid, a malfunctioning transmission control module, or issues with the transmission itself.

3. How can I diagnose the OBDII code C0387 GMC "Unable to Complete Shift"?

- Diagnose the code by checking the transmission fluid level, inspecting the shift solenoid, scanning the transmission control module for trouble codes, and performing a thorough transmission inspection.

4. What repairs may be needed for OBDII code C0387 GMC "Unable to Complete Shift"?

- Repairs may include topping up or changing the transmission fluid, replacing the shift solenoid, repairing or replacing the transmission control module, or overhauling the transmission.

5. Can driving with OBDII code C0387 GMC "Unable to Complete Shift" cause further damage?

- Driving with this code may lead to more severe transmission issues, reduced fuel efficiency, and potential safety hazards due to erratic shifting behavior.

6. How urgent is it to address OBDII code C0387 GMC "Unable to Complete Shift"?

- It is recommended to address this code promptly to prevent further damage to the transmission and ensure safe and efficient operation of the vehicle.

7. Are there any DIY tips for fixing OBDII code C0387 GMC "Unable to Complete Shift"?

- DIY tips include checking and topping up the transmission fluid, inspecting and cleaning the shift solenoid, and ensuring proper connection of electrical components.

8. Is it necessary to reset the OBDII code C0387 GMC "Unable to Complete Shift" after repairs?

- Yes, it is important to reset the code using an OBDII scanner after repairs to clear the fault code and ensure proper functioning of the transmission system.

9. Can extreme weather conditions affect OBDII code C0387 GMC "Unable to Complete Shift"?

- Extreme weather conditions, such as extreme heat or cold, can exacerbate existing transmission issues associated with this code and should be taken into consideration during diagnosis and repairs.

10. How can regular maintenance help prevent OBDII code C0387 GMC "Unable to Complete Shift"?

- Regular maintenance, such as checking and changing transmission fluid, inspecting transmission components, and addressing any issues promptly, can help prevent the occurrence of this code and maintain optimal transmission performance.

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