AutoCodes – GMC – C120C GMC

C120C GMC Code - Brake Pedal Position Sensor 4 Not Plausible

Quick Answer

The Electronic Brake Control Module (EBCM) uses inputs from the electronic brake control brake pedal position sensor to determine when the brake is applied and how much force is used. Common causes include Faulty Brake Pedal Position Sensor, Brake Pedal Position Sensor harness is open or shorted, Brake Pedal Position Sensor 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: C120C GMC indicates Brake Pedal Position Sensor 4 Not Plausible.
Common causes: Common causes include Faulty Brake Pedal Position Sensor, Brake Pedal Position Sensor harness is open or shorted, Brake Pedal Position Sensor 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 1,041

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 Jun 18, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code C120C GMC Description

The Electronic Brake Control Module (EBCM) uses inputs from the electronic brake control brake pedal position sensor to determine when the brake is applied and how much force is used. The electronic brake control module monitors when the driver's foot is on the brake and locks the offset. The offset is locked when 3 out of the 4 inputs indicate the brake pedal is applied. The 4 inputs are brake pedal travel 1, brake pedal travel 2, master cylinder pressure sensor, and the brake pedal position sensor. These inputs are used to determine the driver's braking intent which is used to the control amount of pressure applied to the wheels.

OBDII Code C120C GMC - Brake Pedal Position Sensor 4 Not Plausible - AutoCodes.com — C120C GMC Code - Brake Pedal Position Sensor 4 Not Plausible

What does this mean?

What are the Possible Causes of the DTC C120C GMC?

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

How to Fix the DTC C120C 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 C120C 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.