AutoCodes – GMC – B2645 2017 GMC Sierra

B2645 2017 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 2017 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 174

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
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code B2645 2017 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 2017 GMC Sierra - Ambient Light Sensor Circuit - AutoCodes.com — B2645 2017 GMC Sierra Code - Ambient Light Sensor Circuit

What does this mean?

What are the Possible Causes of the DTC B2645 2017 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 2017 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 2017 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 B2645 2017 GMC Sierra code?

Need more information on how to fix the B2645 2017 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B2645 2017 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 2017 GMC Sierra Code

1. What are the common symptoms of OBDII code B2645 on a 2017 GMC Sierra related to the Ambient Light Sensor Circuit?

The common symptoms include erratic behavior of interior lights, automatic headlights not functioning correctly, and possibly an illuminated dashboard warning light.

2. What are the possible causes of OBDII code B2645 on a 2017 GMC Sierra?

The code B2645 typically indicates a fault in the ambient light sensor circuit. Possible causes can include a faulty ambient light sensor, damaged wiring or connectors, or a malfunctioning control module.

3. How can I diagnose the issue causing OBDII code B2645 on my 2017 GMC Sierra?

To diagnose the issue, you can start by visually inspecting the ambient light sensor and its wiring for any visible damage. Using a multimeter, you can test the sensor's resistance and voltage values to determine if it is functioning properly.

4. Can I repair the ambient light sensor circuit issue causing OBDII code B2645 on my 2017 GMC Sierra myself?

Depending on your knowledge and experience with automotive electrical systems, you may be able to repair the ambient light sensor circuit issue yourself by replacing the faulty sensor, repairing damaged wiring, or addressing any connector issues.

5. Is it safe to continue driving my 2017 GMC Sierra with OBDII code B2645 related to the Ambient Light Sensor Circuit?

While the code itself may not directly affect the drivability of the vehicle, it is recommended to address the issue promptly to ensure proper functioning of the ambient light sensor and related systems.

6. Can extreme weather conditions impact the ambient light sensor circuit and trigger OBDII code B2645 on a 2017 GMC Sierra?

Yes, extreme weather conditions such as excessive sunlight exposure or moisture can potentially affect the ambient light sensor's performance and contribute to triggering the B2645 code.

7. How much does it typically cost to repair the ambient light sensor circuit issue causing OBDII code B2645 on a 2017 GMC Sierra?

The cost of repairing the ambient light sensor circuit issue can vary depending on the extent of the problem and whether you choose to do the repair yourself or seek professional assistance. Costs may include parts and labor.

8. Are there any preventive measures I can take to avoid encountering OBDII code B2645 related to the Ambient Light Sensor Circuit on my 2017 GMC Sierra?

Regularly inspecting the ambient light sensor and its wiring for any signs of damage, and addressing any issues promptly, can help prevent the occurrence of the B2645 code on your GMC Sierra.

9. Could a recent collision or impact to the front of my 2017 GMC Sierra be a potential cause of OBDII code B2645 related to the Ambient Light Sensor Circuit?

Yes, a recent collision or impact to the front of the vehicle could potentially damage the ambient light sensor or its wiring, leading to the triggering of the B2645 code.

10. How long does it typically take to repair the ambient light sensor circuit issue causing OBDII code B2645 on a 2017 GMC Sierra?

The repair time can vary depending on the exact cause of the issue and the expertise of the person performing the repair. In general, it may take anywhere from a few hours to a day to address the ambient light sensor circuit problem.