AutoCodes – GMC – B2645 2016 GMC Sierra

B2645 2016 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 2016 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 190

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 2016 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 2016 GMC Sierra - Ambient Light Sensor Circuit - AutoCodes.com — B2645 2016 GMC Sierra Code - Ambient Light Sensor Circuit

What does this mean?

What are the Possible Causes of the DTC B2645 2016 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 2016 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 2016 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 2016 GMC Sierra Code

1. What are the common symptoms of OBDII code B2645 in a 2016 GMC Sierra related to the Ambient Light Sensor Circuit?

- The common symptoms include erratic behavior of automatic headlights, inconsistent dimming of interior lights, and malfunctioning ambient light adjustments.

2. What are the possible causes of OBDII code B2645 in a 2016 GMC Sierra?

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

3. How can I diagnose the issue causing OBDII code B2645 in my 2016 GMC Sierra?

- To diagnose the issue, you can start by visually inspecting the ambient light sensor and its wiring for any signs of damage. Using a multimeter, test the sensor's resistance and voltage. You may also need a diagnostic scanner to retrieve more specific fault codes and data.

4. Is it safe to continue driving my 2016 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 you may experience issues with the automatic lighting control system. It is recommended to address the problem promptly to avoid further complications.

5. How can I repair OBDII code B2645 in my 2016 GMC Sierra?

- The repair process may involve replacing the ambient light sensor, repairing or replacing damaged wiring or connectors, or reprogramming the ambient light sensor control module. It is advisable to consult a professional mechanic for an accurate diagnosis and repair.

6. Can extreme weather conditions affect the functionality of the Ambient Light Sensor Circuit in a 2016 GMC Sierra?

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

7. How much does it typically cost to repair OBDII code B2645 in a 2016 GMC Sierra at a dealership or repair shop?

- The cost of repairing OBDII code B2645 can vary depending on the extent of the issue and the specific repairs needed. On average, you can expect to pay between $100 to $300 for parts and labor.

8. Can resetting the ambient light sensor system clear OBDII code B2645 in a 2016 GMC Sierra?

- Resetting the system may temporarily clear the code, but if the underlying issue causing the fault code is not addressed, the code is likely to reappear. It is recommended to diagnose and fix the root cause of the problem.

9. Are there any preventive maintenance tips to avoid OBDII code B2645 in a 2016 GMC Sierra?

- Regularly inspecting the ambient light sensor and its wiring for damage, keeping the sensor clean from dirt or debris, and avoiding harsh environmental conditions can help prevent issues leading to OBDII code B2645.

10. Will OBDII code B2645 cause my 2016 GMC Sierra to fail an emissions test?

- OBDII code B2645 related to the Ambient Light Sensor Circuit is not directly related to emissions, so it should not cause your vehicle to fail an emissions test. However, it is still important to address the issue for proper functioning of the lighting system.