AutoCodes – GMC – P1631 2018 GMC Sierra

P1631 2018 GMC Sierra Code - Theft Deterrent Start Enable Signal Not Correct

Quick Answer

The Body Control Module (BCM) sends the pre-release information to the Engine Control Module (ECM) via the serial data circuit. Common causes include Perform security relearn procedure, Faulty Ignition switch assembly, Ignition switch assembly 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: P1631 2018 GMC Sierra indicates Theft Deterrent Start Enable Signal Not Correct.
Common causes: Common causes include Perform security relearn procedure, Faulty Ignition switch assembly, Ignition switch assembly 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 259

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 Aug 17, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P1631 2018 GMC Sierra Description

The Body Control Module (BCM) sends the pre-release information to the Engine Control Module (ECM) via the serial data circuit. The ECM then sends a challenge to the BCM. Both the ECM and BCM perform a calculation on this challenge. If the calculated response from the BCM equals the calculation performed by the ECM, the ECM will allow the vehicle to start. The BCM follows this action by sending the remaining immobilizer data to the ECM. If the immobilizer data sent by the BCM matches that stored by the ECM, the ECM will allow the engine to remain running. The Diagnostic Trouble Code (DTC) will be set if the ECM receives incorrect immobilizer data from the BCM.

OBDII Code P1631 2018 GMC Sierra - Theft Deterrent Start Enable Signal Not Correct - AutoCodes.com — P1631 2018 GMC Sierra Code - Theft Deterrent Start Enable Signal Not Correct

What does this mean?

What are the Possible Causes of the DTC P1631 2018 GMC Sierra?

Perform security relearn procedure
Faulty Ignition switch assembly
Ignition switch assembly harness is open or shorted
Ignition switch assembly circuit poor electrical connection

How to Fix the DTC P1631 2018 GMC Sierra?

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 does this mean?

Code Tech Notes

Security Relearn Procedure:

-Insert the key, attempt to start the vehicle, and leave the key in the ON position.
In some vehicles, the Battery and Security light will blink for several seconds, and then shut off. Then the Security light will then remain ON. Leave the ignition ON until the Security light goes OFF. This will take more than 5 mins.
-When the Security light goes OFF, turn the ignition to the OFF position.
-Leave ignition OFF for 20 Seconds.
-Attempt to start the vehicle again and leave the key in the ON position.
-In some vehicles, the Battery and Security light will blink for several seconds, and then shut off. Then the Security light will then remain ON. Leave the ignition ON until the Security light goes OFF. This will take more than 5 mins.
-Turn the ignition to the OFF position for 20 Seconds.
-Attempt to start the vehicle again and leave the key in the ON position.
-In some vehicles, the Battery and Security light will blink for several seconds, and then shut off. Then the Security light will then remain ON. Leave the ignition ON until the Security light goes OFF. This will take more than 5 mins.
-Once this entire procedure has been completed (three times) your vehicle will start on the fourth attempt.

Note: Some vehicles perform the relearn in a different sequence. You may notice your security light, battery light, and abs light will alternate. Once the security light is left out of the sequence that is considered one step. Repeat the procedure two more times and on the fourth time, your vehicle will start.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1631 2018 GMC Sierra 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 P1631 2018 GMC Sierra code?

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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 P1631 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P1631 in a 2018 GMC Sierra?

The common symptoms of OBDII code P1631 in a 2018 GMC Sierra include the vehicle not starting, the security light flashing, and a message indicating "Theft Deterrent System Problem" on the dashboard.

2. What does the OBDII code P1631 indicate in a 2018 GMC Sierra?

OBDII code P1631 in a 2018 GMC Sierra indicates a problem with the Theft Deterrent Start Enable Signal not being correct, which can prevent the vehicle from starting.

3. What are the possible causes of OBDII code P1631 in a 2018 GMC Sierra?

Possible causes of OBDII code P1631 in a 2018 GMC Sierra include a faulty ignition key, issues with the ignition switch, problems with the immobilizer system, or a malfunction in the body control module.

4. How can I diagnose the OBDII code P1631 in my 2018 GMC Sierra?

Diagnosing OBDII code P1631 in a 2018 GMC Sierra may involve checking for any loose connections in the ignition system, testing the ignition key for proper functioning, and using a diagnostic scanner to retrieve specific error codes related to the theft deterrent system.

5. Can I drive my 2018 GMC Sierra with OBDII code P1631?

It is not recommended to drive your 2018 GMC Sierra with OBDII code P1631, as this code indicates a security issue that may prevent the vehicle from starting or lead to unexpected engine shutdowns.

6. How can I repair OBDII code P1631 in my 2018 GMC Sierra?

Repairing OBDII code P1631 in a 2018 GMC Sierra may involve reprogramming the ignition key, replacing a faulty ignition switch, repairing the immobilizer system, or resetting the body control module to resolve the issue.

7. Is it safe to reset the OBDII code P1631 in a 2018 GMC Sierra using a diagnostic scanner?

Resetting OBDII code P1631 in a 2018 GMC Sierra using a diagnostic scanner may clear the error code temporarily, but it is crucial to address the root cause of the issue to prevent the code from reoccurring and ensure the vehicle's security system is functioning correctly.

8. Can a DIY enthusiast fix OBDII code P1631 in a 2018 GMC Sierra?

While some basic troubleshooting steps can be performed by a DIY enthusiast, diagnosing and repairing OBDII code P1631 in a 2018 GMC Sierra may require specialized tools and expertise, so it is advisable to consult a professional mechanic for a thorough inspection and repair.

9. How much does it typically cost to repair OBDII code P1631 in a 2018 GMC Sierra?

The cost of repairing OBDII code P1631 in a 2018 GMC Sierra can vary depending on the specific cause of the issue, parts needed for replacement, and labor charges. It is recommended to obtain quotes from reputable repair shops or dealerships for an accurate estimate.

10. Will OBDII code P1631 in a 2018 GMC Sierra affect the vehicle's performance?

OBDII code P1631 in a 2018 GMC Sierra may not directly impact the vehicle's performance once the issue is resolved. However, unresolved security system problems can lead to starting issues or potential engine immobilization, affecting the overall functionality of the vehicle.