AutoCodes – GMC – C0266 GMC

C0266 GMC Code - EBCM Motor Relay Circuit High When Off

Quick Answer

The ABS relay supplies battery voltage to six valve solenoids (RF dump/isolation, LF dump/isolation, and rear dump/isolation). Common causes include Faulty Electronic Brake Control Module (EBCM), Electronic Brake Control Module (EBCM) harness is open or shorted, Electronic Brake Control Module (EBCM) 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: C0266 GMC indicates EBCM Motor Relay Circuit High When Off.
Common causes: Common causes include Faulty Electronic Brake Control Module (EBCM), Electronic Brake Control Module (EBCM) harness is open or shorted, Electronic Brake Control Module (EBCM) 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 2,410

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 May 02, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C0266 GMC Description

The ABS relay supplies battery voltage to six valve solenoids (RF dump/isolation, LF dump/isolation, and rear dump/isolation). The Electronic Brake Control Module (EBCM) microprocessor applies the grounds needed to activate each solenoid. The low side of each solenoid coil has a feedback circuit to the EBCM microprocessor. When a solenoid is commanded OFF, the feedback voltage is high. When a solenoid is commanded ON, the feedback voltage is low.

OBDII Code C0266 GMC - EBCM Motor Relay Circuit High When Off - AutoCodes.com — C0266 GMC Code - EBCM Motor Relay Circuit High When Off

What does this mean?

What are the Possible Causes of the DTC C0266 GMC?

Faulty Electronic Brake Control Module (EBCM)
Electronic Brake Control Module (EBCM) harness is open or shorted
Electronic Brake Control Module (EBCM) circuit poor electrical connection

How to Fix the DTC C0266 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 C0266 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.

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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 C0266 GMC Code

1. What are the common symptoms of OBDII code C0266 in a GMC vehicle?

- Common symptoms include the ABS warning light staying on, traction control issues, and potential loss of ABS functionality.

2. What does the OBDII code C0266 indicating "EBCM Motor Relay Circuit High When Off" mean?

- This code indicates a problem with the Electronic Brake Control Module (EBCM) motor relay circuit being stuck in the high position when the motor is off.

3. What are the possible causes of OBDII code C0266 in a GMC vehicle?

- Possible causes include a faulty EBCM motor relay, wiring issues, a malfunctioning EBCM module, or a problem with the ABS system.

4. How can I diagnose the EBCM motor relay circuit high issue in my GMC vehicle?

- Diagnosing this issue typically involves using a scan tool to retrieve the trouble codes, performing a visual inspection of the wiring, and testing the EBCM motor relay for proper functionality.

5. Can I drive my GMC vehicle with OBDII code C0266 present?

- It is not recommended to drive your vehicle with this code present, as it can affect the ABS system's operation and compromise your vehicle's safety.

6. How can I repair OBDII code C0266 in my GMC vehicle?

- Repairing this code may involve replacing the EBCM motor relay, repairing any damaged wiring, or addressing any other underlying issues related to the ABS system.

7. Is it safe to continue driving my GMC vehicle if the ABS warning light is on due to code C0266?

- It is best to avoid driving the vehicle until the issue is diagnosed and repaired to ensure the ABS system functions correctly in case of an emergency braking situation.

8. Can a DIY enthusiast fix OBDII code C0266 in a GMC vehicle?

- Depending on your automotive repair skills and access to tools, you may be able to diagnose and repair this issue yourself. However, seeking professional help is recommended for complex ABS system problems.

9. Will resetting the trouble codes make OBDII code C0266 go away temporarily?

- Resetting the trouble codes may temporarily clear the ABS warning light, but the underlying issue causing code C0266 will persist until properly diagnosed and repaired.

10. How much does it typically cost to fix OBDII code C0266 in a GMC vehicle?

- The cost of fixing this code can vary depending on the exact cause of the issue, but it may involve parts and labor expenses ranging from $200 to $500 or more.