AutoCodes – GMC – B3935 GMC

B3935 GMC Code - Transponder Authentication

Quick Answer

When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the key is energized by the exciter coil surrounding the ignition lock cylinder. Common causes include Faulty Key/Transmitter, Faulty Body Control Module (BCM). 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: B3935 GMC indicates Transponder Authentication.
Common causes: Common causes include Faulty Key/Transmitter, Faulty Body Control Module (BCM).
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 5,300

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 17, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B3935 GMC Description

When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the key is energized by the exciter coil surrounding the ignition lock cylinder. The transponder transmits a signal to the immobilizer control module. The immobilizer control module translates this signal to a serial data message which is sent to the Body Control Module (BCM). The BCM then compares this value to a value stored in memory. If the value is correct, the BCM will send the prerelease password via the serial data circuit to the Engine Control Module (ECM) If the learned key code does not match or a transponder value is not received, the BCM will send the start disable password to the ECM.

OBDII Code B3935 GMC - Transponder Authentication - AutoCodes.com — B3935 GMC Code - Transponder Authentication

What does this mean?

What are the Possible Causes of the DTC B3935 GMC?

Faulty Key/Transmitter
Faulty Body Control Module (BCM)

How to Fix the DTC B3935 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 B3935 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 B3935 GMC code?

Need more information on how to fix the B3935 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3935 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

B3935 2014 GMC Sierra — Transponder Authentication
B3935 2015 GMC Sierra — Transponder Authentication
B3935 2016 GMC Sierra — Transponder Authentication
B3935 2017 GMC Sierra — Transponder Authentication
B3935 2018 GMC Sierra — Transponder Authentication

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 B3935 GMC Code

1. What does OBDII code B3935 GMC indicate?

The code B3935 GMC refers to Transponder Authentication Failure.

2. What are the common symptoms of OBDII code B3935 GMC?

Common symptoms include issues with starting the vehicle, engine stalling, and the security light illuminating on the dashboard.

3. What can cause the OBDII code B3935 GMC to trigger?

The code B3935 GMC is typically triggered by problems with the vehicle's key, transponder, immobilizer system, or related components.

4. How can I diagnose the cause of OBDII code B3935 GMC?

Diagnosing the code B3935 GMC may require specialized diagnostic equipment to test the key, transponder, and immobilizer system for faults.

5. What are some repair tips for addressing OBDII code B3935 GMC?

Repair tips may include checking the key for damage, ensuring the transponder is functioning properly, and verifying the immobilizer system is communicating correctly.

6. Can I fix OBDII code B3935 GMC on my own?

Fixing the code B3935 GMC may require advanced automotive knowledge and specialized tools, so seeking assistance from a professional technician is recommended.

7. Is it safe to drive with OBDII code B3935 GMC active?

It is not recommended to drive with the code B3935 GMC active, as it may lead to potential starting or stalling issues while driving.

8. How much does it cost to repair OBDII code B3935 GMC?

The cost of repairing the code B3935 GMC can vary depending on the exact cause of the issue and the labor rates of the repair shop.

9. Can OBDII code B3935 GMC be a recurring problem?

If the underlying issue causing the code B3935 GMC is not properly diagnosed and repaired, it may recur in the future.

10. Are there any preventive measures to avoid OBDII code B3935 GMC?

Regular maintenance of the vehicle's key, transponder, and immobilizer system can help prevent issues that may trigger the code B3935 GMC.

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