AutoCodes – Generic – C0266

C0266 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 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.

Save to My Repairs My Repairs

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

Code Popularity 5,824

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
Add Comment

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

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

What does this mean?

What are the Possible Causes of the DTC C0266?

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?

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 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 C0266 code?

Need more information on how to fix the C0266 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the C0266 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

C0266 Buick — EBCM Motor Relay Circuit High When Off
C0266 Cadillac — EBCM Motor Relay Circuit High When Off
C0266 Chevrolet — EBCM Motor Relay Circuit High When Off
C0266 GMC — EBCM Motor Relay Circuit High When Off

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 Code

1. What are the common symptoms of OBDII code C0266 (EBCM Motor Relay Circuit High When Off)?

- Common symptoms include the ABS warning light on the dashboard, loss of ABS functionality, and potential issues with the vehicle's stability control system.

2. What are some possible causes of OBDII code C0266?

- Possible causes include a faulty electronic brake control module (EBCM), a malfunctioning EBCM motor relay, damaged wiring or connectors in the circuit, or a software issue.

3. How can I diagnose the EBCM motor relay circuit high when off error?

- Diagnosis typically involves using a professional OBDII scanner to retrieve the trouble code and then conducting a thorough inspection of the EBCM, relay, wiring, and connectors for any visible damage or issues.

4. Can I still drive my vehicle with OBDII code C0266 present?

- While it might be possible to drive the vehicle, it is not recommended as the ABS and stability control systems may not function properly, compromising safety. It is best to address the issue promptly.

5. How should I repair OBDII code C0266 (EBCM Motor Relay Circuit High When Off)?

- Repair typically involves replacing the faulty EBCM, addressing any issues with the motor relay, repairing damaged wiring or connectors, and clearing the trouble code with a scanner.

6. Is it safe to ignore OBDII code C0266 and continue driving?

- Ignoring the code is not advisable as it can lead to potential safety hazards due to the compromised ABS and stability control systems. It is recommended to address the issue promptly.

7. Can a DIY enthusiast fix OBDII code C0266 at home?

- Depending on the individual's skill level and access to tools, some DIY enthusiasts may be able to address the issue by replacing the EBCM, checking the motor relay, and inspecting wiring connections carefully.

8. How much does it typically cost to repair OBDII code C0266?

- The cost of repair can vary depending on the extent of the issue, the parts needed, and whether professional labor is required. It is advisable to consult with a mechanic for a more accurate estimate.

9. Will resetting the trouble code fix OBDII code C0266 permanently?

- Simply resetting the trouble code without addressing the underlying issue will not fix OBDII code C0266 permanently. It is crucial to diagnose and repair the root cause of the problem.

10. How long does it take to repair OBDII code C0266?

- The repair time can vary based on the complexity of the issue, availability of parts, and the expertise of the technician. In some cases, it may be resolved within a few hours, while more extensive repairs could take longer.