AutoCodes – GMC – C1277 GMC

C1277 GMC Code - Requested Torque Signal Circuit Malfunction

Quick Answer

The Electronic Brake Control Module (EBCM) and the Powertrain Control Module (PCM) simultaneously control the traction control. Common causes include Faulty Electronic Brake Control Module (EBCM), Faulty Powertrain Control Module (PCM), EBCM harness is open or shorted. 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: C1277 GMC indicates Requested Torque Signal Circuit Malfunction.
Common causes: Common causes include Faulty Electronic Brake Control Module (EBCM), Faulty Powertrain Control Module (PCM), EBCM harness is open or shorted.
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 5,699

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Sep 02, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C1277 GMC Description

The Electronic Brake Control Module (EBCM) and the Powertrain Control Module (PCM) simultaneously control the traction control. The EBCM sends a Requested Torque message via a pulse width modulated (PWM) signal to the PCM. The duty cycle of the signal is used to determine how much engine torque the EBCM is requesting the PCM to deliver. Normal values are between 10 and 90 percent duty cycle. The signal should be at 90 percent when traction control is not active and at lower values during traction control activations. The PCM supplies the pull up voltage that the EBCM switches to ground to create the signal.

OBDII Code C1277 GMC - Requested Torque Signal Circuit Malfunction - AutoCodes.com — C1277 GMC Code - Requested Torque Signal Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC C1277 GMC?

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

How to Fix the DTC C1277 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 C1277 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 C1277 GMC Code

What does OBDII code C1277 mean for a GMC vehicle?

C1277 indicates a malfunction in the Requested Torque Signal Circuit, which is responsible for relaying torque requests between the engine control module (ECM) and other systems like the traction control module.

What are the common symptoms of code C1277 in a GMC?

Symptoms may include reduced engine power, activation of the traction control warning light, poor acceleration, or the ABS light turning on.

What causes code C1277 to appear in a GMC vehicle?

Possible causes include a faulty torque signal circuit, damaged wiring or connectors, issues with the ECM or traction control module, or communication errors between modules.

Can driving with code C1277 damage my GMC vehicle?

While driving with code C1277 may not cause immediate damage, it can lead to reduced performance and increase the risk of losing traction control functionality, which may compromise safety.

How can I diagnose the cause of code C1277?

Diagnose the issue by inspecting the wiring and connectors in the torque signal circuit, checking for module communication errors, and using a scan tool to monitor torque signal data.

What tools are needed to troubleshoot code C1277?

A professional-grade OBDII scan tool capable of reading manufacturer-specific codes and live data, along with a multimeter to test electrical connections, is recommended.

How can I fix code C1277 on a GMC vehicle?

Common fixes include repairing or replacing damaged wiring or connectors, updating software in the ECM or traction control module, or replacing faulty modules if necessary.

Is code C1277 specific to GMC vehicles?

While C1277 can appear on other manufacturersâ€™ vehicles, its exact meaning and system interactions may vary. In GMC vehicles, it is often related to the torque signal circuit.

Can a software update resolve code C1277?

In some cases, a software update for the ECM or related control modules can resolve communication issues tied to code C1277.

How much does it cost to repair code C1277 on a GMC?

The repair cost can vary widely depending on the root cause, ranging from $100 for simple wiring repairs to over $1,000 if module replacement is required.