AutoCodes – GMC – C0402 GMC

C0402 GMC Code - Transfer Case Solenoid Valve

Quick Answer

The rear drive clutch solenoid valve is internal to the torque transfer device housing. Common causes include Faulty Transfer Case Solenoid Valve, Transfer Case Solenoid Valve harness is open or shorted, Transfer Case Solenoid Valve 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: C0402 GMC indicates Transfer Case Solenoid Valve.
Common causes: Common causes include Faulty Transfer Case Solenoid Valve, Transfer Case Solenoid Valve harness is open or shorted, Transfer Case Solenoid Valve 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 1,221

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 Jul 04, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code C0402 GMC Description

The rear drive clutch solenoid valve is internal to the torque transfer device housing. The rear differential clutch control module supplies battery voltage to the control circuit and ground to the low reference circuit of the solenoid valve. The solenoid valve is controlled by a pulse width modulation (PWM) signal. The solenoid valve controls the hydraulic pressure to the clutch package of the torque transfer device. The locking level of the torque transfer device depends on the engagement of the clutch package.

OBDII Code C0402 GMC - Transfer Case Solenoid Valve - AutoCodes.com — C0402 GMC Code - Transfer Case Solenoid Valve

What does this mean?

What are the Possible Causes of the DTC C0402 GMC?

Faulty Transfer Case Solenoid Valve
Transfer Case Solenoid Valve harness is open or shorted
Transfer Case Solenoid Valve circuit poor electrical connection

How to Fix the DTC C0402 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 does this mean?

Code Tech Notes

- C0402 02 Transfer Case Solenoid Valve Short to Ground
- C0402 04 Transfer Case Solenoid Valve Open
- C0402 42 Transfer Case Solenoid Valve Calibration Not Programmed
- C0402 43 Transfer Case Solenoid Valve EEPROM Incorrect Programming
- C0402 4B Transfer Case Solenoid Valve Calibration Not Learned
- C0402 61 Transfer Case Solenoid Valve Stuck

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C0402 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 C0402 GMC code?

Need more information on how to fix the C0402 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the C0402 GMC code diagnosed by a professional: Find a repair shop in your area

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 C0402 GMC Code

What does the OBDII code C0402 mean for a GMC vehicle?

C0402 indicates a problem with the transfer case solenoid valve, which is responsible for controlling the transfer case's operation in four-wheel drive systems.

What are common symptoms of the C0402 code?

Common symptoms include the illumination of the check engine light, difficulty engaging or disengaging four-wheel drive, and unusual noises from the transfer case.

What could cause the C0402 code to trigger?

Possible causes include a faulty transfer case solenoid valve, damaged wiring or connectors, low transmission fluid levels, or issues with the transfer case itself.

How can I diagnose the C0402 code?

To diagnose the C0402 code, use an OBDII scanner to confirm the code, inspect the transfer case solenoid and wiring, check fluid levels, and test the solenoid's operation with a multimeter.

What are some common repair solutions for the C0402 code?

Repairs may involve replacing the transfer case solenoid valve, repairing or replacing damaged wiring or connectors, or addressing low fluid levels in the transfer case.

Will driving with the C0402 code cause further damage?

Yes, continuing to drive with the C0402 code can lead to more significant issues with the transfer case or transmission if the problem is not addressed.

Can I clear the C0402 code without fixing the problem?

While you can clear the code with a scanner, the code will likely return if the underlying issue with the transfer case solenoid valve is not resolved.

Is it safe to drive my GMC with the C0402 code?

It is not recommended to drive your GMC with the C0402 code, as it may affect your vehicle's ability to switch between two-wheel and four-wheel drive, potentially leading to unsafe driving conditions.

How much does it typically cost to repair the C0402 code?

Repair costs can vary widely but generally range from $100 to $500, depending on the specific issue, whether it's a simple wiring fix or a complete solenoid replacement.