AutoCodes – GMC – B2645 2014 GMC Sierra

B2645 2014 GMC Sierra Code - Ambient Light Sensor Circuit

Quick Answer

The ambient light sensor is used to monitor outside lighting conditions. Common causes include Faulty Ambient Light/Sunload Sensor, Ambient Light/Sunload Sensor harness is open or shorted, Ambient Light/Sunload 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: B2645 2014 GMC Sierra indicates Ambient Light Sensor Circuit.
Common causes: Common causes include Faulty Ambient Light/Sunload Sensor, Ambient Light/Sunload Sensor harness is open or shorted, Ambient Light/Sunload 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 202

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 29, 2023

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code B2645 2014 GMC Sierra Description

The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between 0.2 and 4.9 V depending on outside lighting conditions. The Body Control Module (BCM) provides a 5 V reference signal to the ambient light sensor and the Heating, Ventilation, and Air Conditioning (HVAC) control module provides a low reference ground. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either Daytime Running Lights (DRL) or automatic lamp control when the headlamp switch is in the AUTO position. In daylight conditions, the BCM will command the daytime running lamps ON. During low light conditions, the BCM will command the low beam headlamps ON. Any function or condition that turns on the headlamps will cancel daytime running lamps operation.

OBDII Code B2645 2014 GMC Sierra - Ambient Light Sensor Circuit - AutoCodes.com — B2645 2014 GMC Sierra Code - Ambient Light Sensor Circuit

What does this mean?

What are the Possible Causes of the DTC B2645 2014 GMC Sierra?

Faulty Ambient Light/Sunload Sensor
Ambient Light/Sunload Sensor harness is open or shorted
Ambient Light/Sunload Sensor circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC B2645 2014 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

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B2645 2014 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.

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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 B2645 2014 GMC Sierra Code

1. What does the OBDII code B2645 mean on a 2014 GMC Sierra?

Code B2645 indicates an issue with the ambient light sensor circuit, which monitors exterior lighting conditions to adjust the vehicle's lighting systems accordingly.

2. What are the common symptoms of code B2645 in a 2014 GMC Sierra?

Common symptoms include malfunctioning automatic headlights, improper dimming or brightness of the instrument cluster, or a dashboard warning light.

3. What causes the B2645 code to appear in a 2014 GMC Sierra?

Typical causes include a faulty ambient light sensor, damaged wiring or connectors in the sensor circuit, or a malfunction in the Body Control Module (BCM).

4. How do I diagnose the B2645 code in my 2014 GMC Sierra?

Start by scanning the vehicle with an OBDII scanner to confirm the code. Then inspect the ambient light sensor, wiring, and connectors for damage or corrosion. Test the sensor's functionality with a multimeter if needed.

5. Can I drive my 2014 GMC Sierra with the B2645 code active?

Yes, you can drive the vehicle, but the automatic lighting features may not work properly, which could reduce visibility under certain conditions.

6. How do I fix the B2645 code on a 2014 GMC Sierra?

Repairs may include replacing the ambient light sensor, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the BCM if necessary.

7. Where is the ambient light sensor located in a 2014 GMC Sierra?

The ambient light sensor is typically located on the dashboard near the windshield, where it can detect external light conditions.

8. How much does it cost to repair a B2645 code on a 2014 GMC Sierra?

Repair costs vary, but replacing the ambient light sensor generally costs $50â€“$150 for parts, plus labor if done by a mechanic.

9. Can a dead battery trigger the B2645 code in a 2014 GMC Sierra?

A dead or weak battery can sometimes cause electrical issues, including triggering this code. Ensure the battery is fully charged and functional before further diagnosis.

10. Do I need to clear the B2645 code manually after repairs?

Yes, after completing the repairs, use an OBDII scanner to clear the code. If the issue is resolved, the code should not return.