AutoCodes – GMC – B2645 GMC

B2645 GMC 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 GMC 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 4,204

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

What does this mean?

What are the Possible Causes of the DTC B2645 GMC?

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 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 does this mean?

Code Tech Notes

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B2645 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 B2645 GMC code?

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Information for Specific GMC Models

B2645 2014 GMC Sierra — Ambient Light Sensor Circuit
B2645 2015 GMC Sierra — Ambient Light Sensor Circuit
B2645 2016 GMC Sierra — Ambient Light Sensor Circuit
B2645 2017 GMC Sierra — Ambient Light Sensor Circuit
B2645 2018 GMC Sierra — Ambient Light Sensor Circuit

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 GMC Code

1. What are the common symptoms of OBDII code B2645 GMC (Ambient Light Sensor Circuit)?

- Common symptoms include erratic interior lighting behavior, automatic headlight malfunctions, and the inability to adjust interior lighting based on ambient light conditions.

2. What are the possible causes of OBDII code B2645 GMC (Ambient Light Sensor Circuit)?

- Possible causes may include a faulty ambient light sensor, damaged wiring or connectors in the circuit, or issues with the lighting control module.

3. How can I diagnose the Ambient Light Sensor Circuit issue related to OBDII code B2645 GMC?

- To diagnose the problem, you can use a scan tool to read the trouble code, inspect the ambient light sensor for physical damage, and check the wiring and connectors for any signs of wear or corrosion.

4. Can a DIY enthusiast repair the Ambient Light Sensor Circuit issue causing OBDII code B2645 GMC?

- While some DIY enthusiasts may be able to replace a faulty ambient light sensor or repair simple wiring issues, it is recommended to consult a professional technician for a proper diagnosis and repair.

5. What are the potential consequences of ignoring OBDII code B2645 GMC (Ambient Light Sensor Circuit)?

- Ignoring this code may lead to continued malfunctions of the interior lighting system, potential safety hazards while driving in low-light conditions, and possible drainage on the vehicle's battery.

6. How much does it typically cost to repair the Ambient Light Sensor Circuit issue associated with OBDII code B2645 GMC?

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

7. Will resetting the OBDII code B2645 GMC (Ambient Light Sensor Circuit) make the issue go away?

- Resetting the code may temporarily clear the warning light, but it will not fix the underlying problem causing the code to trigger. It is important to address the root cause of the issue for a permanent solution.

8. Can extreme weather conditions affect the performance of the Ambient Light Sensor Circuit in a GMC vehicle?

- Yes, extreme weather conditions such as heavy rain, snow, or intense sunlight can potentially impact the performance of the ambient light sensor and contribute to the triggering of OBDII code B2645.

9. Is it safe to continue driving with OBDII code B2645 GMC (Ambient Light Sensor Circuit) present?

- While it may be safe to drive in daylight conditions, it is not recommended to ignore the code as it can lead to unpredictable lighting behavior at night or in low-light situations, compromising safety.

10. How long does it typically take to repair the Ambient Light Sensor Circuit issue associated with OBDII code B2645 GMC?

- The repair time can vary depending on the complexity of the issue and the availability of parts, but it may take anywhere from 1 to 3 hours for a professional technician to diagnose and fix the problem.