B3904 GMC 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 GMC 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 GMC 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 GMC?
- 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 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 is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the B3904 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.
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Frequently Asked Questions about B3904 GMC Code
1. What are the common symptoms of OBDII code B3904 GMC?
The common symptoms of OBDII code B3904 GMC, Rear Compartment Occupant Sensor Signal Invalid, may include the airbag warning light illuminating on the dashboard and possible issues with the airbag system.
2. What are the possible causes of OBDII code B3904 GMC?
Possible causes of OBDII code B3904 GMC can include a faulty rear compartment occupant sensor, damaged wiring or connectors in the airbag system, or a malfunction in the airbag control module.
3. How can I diagnose OBDII code B3904 GMC?
Diagnosing OBDII code B3904 GMC involves using a diagnostic scanner to retrieve the fault code from the vehicle's computer system and performing a thorough inspection of the rear compartment occupant sensor, wiring, and connections for any signs of damage or malfunction.
4. Can I still drive my vehicle with OBDII code B3904 GMC present?
It is not recommended to drive your vehicle with OBDII code B3904 GMC present, as it indicates a potential issue with the airbag system, which is crucial for occupant safety in the event of a collision.
5. How can I repair OBDII code B3904 GMC?
Repairing OBDII code B3904 GMC may involve replacing the rear compartment occupant sensor, repairing or replacing damaged wiring or connectors, or reprogramming the airbag control module as necessary.
6. Is it safe to reset the OBDII code B3904 GMC without addressing the underlying issue?
Resetting OBDII code B3904 GMC without addressing the underlying issue is not recommended, as the problem with the airbag system may persist and compromise occupant safety in the vehicle.
7. Are there any DIY repair tips for OBDII code B3904 GMC?
DIY repair tips for OBDII code B3904 GMC include checking for loose or damaged wiring connections, inspecting the rear compartment occupant sensor for physical damage, and ensuring all components in the airbag system are properly connected and functioning.
8. How much does it cost to fix OBDII code B3904 GMC at a repair shop?
The cost of fixing OBDII code B3904 GMC at a repair shop can vary depending on the extent of the issue, the specific repairs needed, and the labor rates of the service provider. It is recommended to obtain quotes from multiple shops for comparison.
9. Can OBDII code B3904 GMC affect the functionality of other vehicle systems?
OBDII code B3904 GMC specifically relates to the rear compartment occupant sensor signal and the airbag system, but if left unresolved, it could potentially impact the overall safety of the vehicle and its occupants in the event of a collision.
10. How can I prevent OBDII code B3904 GMC from recurring in the future?
To prevent OBDII code B3904 GMC from recurring in the future, it is essential to address any underlying issues promptly, perform regular maintenance checks on the airbag system, and follow the manufacturer's guidelines for vehicle service intervals.
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