B3904 Chevrolet Code - Rear Compartment Occupant Sensor Signal Invalid
Quick Answer
Rear compartment occupant sensor is connected to battery voltage and ground at all times. Common causes include Faulty Rear Compartment Occupant Sensor, Rear Compartment Occupant Sensor harness is open or shorted, Rear Compartment Occupant 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
- B3904 Chevrolet indicates Rear Compartment Occupant Sensor Signal Invalid.
- Common causes
- Common causes include Faulty Rear Compartment Occupant Sensor, Rear Compartment Occupant Sensor harness is open or shorted, Rear Compartment Occupant 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.
Code B3904 Chevrolet Description
Rear compartment occupant sensor can be disabled by pressing disable switch on rear compartment occupant sensor and holding for 2 seconds. BCM will command trunk ajar telltale on for one minute with each ignition on signal while rear compartment occupant sensor is disabled. Once deck lid is opened, rear compartment occupant sensor will reset to on and resume normal operation. Rear compartment occupant sensor can also be enabled inside of rear compartment with ignition on or off by pressing disable switch. Deck lid ajar switch signal circuit is used for rear compartment occupant sensor class 2 data.
The Diagnostic Trouble Code (DTC) sets when BCM receives an invalid status signal from rear compartment occupant sensor.
What are the Possible Causes of the DTC B3904 Chevrolet?
- Faulty Rear Compartment Occupant Sensor
- Rear Compartment Occupant Sensor harness is open or shorted
- Rear Compartment Occupant Sensor circuit poor electrical connection
- Faulty Body Control Module (BCM)
How to Fix the DTC B3904 Chevrolet?
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 is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the B3904 Chevrolet 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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Frequently Asked Questions about B3904 Chevrolet Code
1. What does the OBDII code B3904 mean on a Chevrolet?
The B3904 code indicates that the Rear Compartment Occupant Sensor Signal is invalid, meaning the system detects an issue with the sensor used to identify occupancy in the rear seats.
2. What are the common symptoms of the B3904 code on a Chevrolet?
Symptoms may include the airbag warning light illuminating, rear seat occupancy detection not functioning properly, or issues with rear passenger safety systems.
3. What causes the B3904 code to appear on a Chevrolet?
Common causes include a faulty rear compartment occupant sensor, damaged wiring or connectors, or a malfunction within the airbag control module.
4. Is the B3904 code related to the airbags in my Chevrolet?
Yes, the B3904 code is tied to the airbag system, as the rear compartment occupant sensor plays a role in determining airbag deployment strategies.
5. Can I drive my Chevrolet with the B3904 code active?
While the vehicle may still be drivable, safety systems like airbags may not function as intended, so it's important to address the issue promptly.
6. How do I diagnose the B3904 code on my Chevrolet?
Diagnosis involves using an OBDII scanner to confirm the code, visually inspecting the rear occupant sensor and its wiring, and testing the sensor's functionality with specialized tools.
7. Can I fix the B3904 code on my Chevrolet myself?
If the issue is due to a loose connection or damaged wiring, you may be able to repair it yourself. However, replacing the sensor or addressing module issues may require professional help.
8. How much does it cost to fix the B3904 code on a Chevrolet?
Repair costs vary depending on the issue. Replacing a rear occupant sensor could cost $100-$300, while more complex wiring or module repairs may be higher.
9. How do I prevent the B3904 code from reoccurring?
Regular inspections of wiring and connectors in the rear seat area can help prevent issues. Avoid placing heavy or unusual objects in the rear seats that may interfere with the sensor.
10. Does the B3904 code require a software update for my Chevrolet?
In some cases, a software update for the airbag control module may be needed to resolve the issue. Check with your dealership to confirm if this applies to your vehicle.
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