AutoCodes – GMC – B2645 2015 GMC Sierra

B2645 2015 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 2015 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 197

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 2015 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 2015 GMC Sierra - Ambient Light Sensor Circuit - AutoCodes.com — B2645 2015 GMC Sierra Code - Ambient Light Sensor Circuit

What does this mean?

What are the Possible Causes of the DTC B2645 2015 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 2015 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 2015 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 2015 GMC Sierra Code

1. What are the common symptoms of OBDII code B2645 on a 2015 GMC Sierra related to the Ambient Light Sensor Circuit?

- The common symptoms include erratic behavior of automatic headlights, dim or overly bright interior lighting, and malfunctioning ambient light sensor readings.

2. What are the possible causes of OBDII code B2645 on a 2015 GMC Sierra?

- The code B2645 can be triggered by a faulty ambient light sensor, damaged wiring or connectors in the ambient light sensor circuit, or a malfunction in the body control module.

3. How can I diagnose the cause of OBDII code B2645 on my 2015 GMC Sierra?

- Diagnose the code by visually inspecting the ambient light sensor and its wiring for any visible damage. Use a multimeter to test the sensor's resistance and check for proper voltage supply to the sensor.

4. Is it safe to drive my 2015 GMC Sierra with OBDII code B2645 related to the Ambient Light Sensor Circuit?

- It is generally safe to drive the vehicle with this code, but be aware that your automatic lighting system may not function correctly. It's recommended to address the issue promptly.

5. Can I reset OBDII code B2645 on my 2015 GMC Sierra without fixing the underlying issue?

- While you can reset the code with an OBDII scanner, it will likely reappear if the root cause, such as a faulty ambient light sensor, is not addressed.

6. How much does it typically cost to repair OBDII code B2645 on a 2015 GMC Sierra related to the Ambient Light Sensor Circuit?

- The repair cost can vary depending on the exact cause of the issue, but it may range from $100 to $300 for parts and labor.

7. Are there any DIY repair tips for fixing OBDII code B2645 on a 2015 GMC Sierra?

- DIY enthusiasts may attempt to replace the ambient light sensor themselves after proper diagnosis. However, if unsure, it's best to consult a professional mechanic.

8. Will fixing OBDII code B2645 on my 2015 GMC Sierra improve fuel efficiency or performance?

- Resolving this specific code is unlikely to directly impact fuel efficiency or performance, as it primarily affects the ambient light sensor functionality.

9. Can extreme weather conditions affect the triggering of OBDII code B2645 on a 2015 GMC Sierra?

- Yes, extreme temperatures or exposure to moisture can sometimes lead to issues with the ambient light sensor circuit, potentially triggering the code.

10. How long does it typically take to repair OBDII code B2645 on a 2015 GMC Sierra at a dealership or repair shop?

- The repair time can vary based on the exact cause and shop workload, but most repairs related to this code can be completed within a few hours to a day.