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AutoCodes – Generic – B2645:03

B2645:03 Code - Ambient Light Sensor Circuit Low Voltage

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
B2645:03 indicates Ambient Light Sensor Circuit Low Voltage.
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 367
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on May 29, 2023
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Code B2645:03 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. The Diagnostic Trouble Code (DTC) will be set when the BCM detects a short to ground in the ambient light sensor signal circuit.
OBDII Code B2645:03 - Ambient Light Sensor Circuit Low Voltage - AutoCodes.com
B2645:03 Code - Ambient Light Sensor Circuit Low Voltage
What does this mean?

What are the Possible Causes of the DTC B2645:03?

  • 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 B2645:03?

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





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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B2645:03 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 B2645:03 Code

1. What does the OBDII code B2645:03 mean?

This code indicates a low voltage issue in the ambient light sensor circuit, which helps the vehicle adjust lighting systems based on external light conditions.

2. What are the common symptoms of code B2645:03?

Symptoms may include malfunctioning auto headlights, dim or overly bright interior lighting, and dashboard warnings related to the lighting system.

3. What causes the B2645:03 code to appear?

Common causes include a faulty ambient light sensor, damaged wiring or connectors, or a malfunctioning body control module (BCM).

4. Can I still drive my car with the B2645:03 code?

Yes, the vehicle is drivable, but automatic lighting features may not work properly, which could affect visibility in changing light conditions.

5. How can I diagnose the B2645:03 code?

Use a scan tool to confirm the code, inspect the ambient light sensor and wiring for damage, and check for proper voltage and ground at the sensor connector.

6. How do I fix the B2645:03 code?

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

7. How much does it cost to repair the B2645:03 code?

Repair costs vary but generally range from $50 to $200, depending on whether the sensor, wiring, or BCM needs replacement or repair.

8. Can I reset the B2645:03 code without fixing the issue?

Clearing the code with a scan tool may temporarily remove it, but it will likely return if the underlying issue is not resolved.

9. Is the ambient light sensor the only component that can trigger code B2645:03?

No, issues with wiring, connectors, or the body control module can also cause this code.

10. How can I prevent the B2645:03 code from recurring?

Regularly inspect and maintain the ambient light sensor and wiring, and address any electrical issues promptly to prevent further damage.

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