B3856 Code - Discard Rollover Sensor
Quick Answer
The inflatable restraint vehicle Rollover Sensor (ROS) utilizes the battery power supply and a bidirectional interface circuit. Common causes include Faulty Rollover Sensor, Rollover Sensor harness is open or shorted, Rollover 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
- B3856 indicates Discard Rollover Sensor.
- Common causes
- Common causes include Faulty Rollover Sensor, Rollover Sensor harness is open or shorted, Rollover 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 B3856 Description
What are the Possible Causes of the DTC B3856?
- Faulty Rollover Sensor
- Rollover Sensor harness is open or shorted
- Rollover Sensor circuit poor electrical connection
- Faulty Sensing and Diagnostic Module (SDM)
How to Fix the DTC B3856?
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 B3856 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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Information for Specific Makes
- B3856 Buick — Discard Rollover Sensor
- B3856 Cadillac — Discard Rollover Sensor
- B3856 Chevrolet — Discard Rollover Sensor
- B3856 GMC — Discard Rollover Sensor
- B3856 Hummer — Discard Rollover Sensor
- B3856 Pontiac — Discard Rollover Sensor
- B3856 Saturn — Discard Rollover Sensor
Precautions for SRS “AIR BAG” and “SEAT BELT PRE-TENSIONER” Service
- Never probe the electrical connectors on air bag, side air curtain modules or seat belts.
- Never disassemble or tamper with safety belt buckle/retractor pretensioners, adaptive load limiting retractors, safety belt inflators, or probe the electrical connectors.
- Do not use electrical test equipment to check SRS circuits unless instructed to in this Service Manual.
- Before servicing the SRS, turn ignition switch OFF, disconnect both battery cables and wait at least 3 minutes. For approximately 3 minutes after the cables are removed, it is still possible for the air bag and seat belt pre-tensioner to deploy. Therefore, do not work on any SRS connectors or wires until at least 3 minutes have passed.
Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.
Frequently Asked Questions about B3856 Code
1. What is OBDII code B3856?
OBDII code B3856 indicates a fault in the "Discard Rollover Sensor" circuit, suggesting a malfunction related to the vehicle’s rollover sensing system, which is crucial for activating safety measures during a rollover accident.
2. What symptoms might I notice if my vehicle has the B3856 code?
Symptoms can include the airbag warning light illuminating on the dashboard, potential failure of the airbag system to deploy correctly in a rollover, and occasionally, error messages related to the stability or traction control systems.
3. What causes the B3856 code to be triggered?
The B3856 code can be triggered by several issues including faulty rollover sensor, damaged wiring or connectors associated with the rollover sensor, or a problem with the airbag control module.
4. How can I diagnose the B3856 code?
Diagnosis involves using a scan tool to read the fault code and examining the rollover sensor and its connections for signs of damage or corrosion. It may also include checking the continuity and resistance in the sensor circuit and assessing the functionality of the airbag control module.
5. What are the steps to repair or fix the B3856 code?
Repair steps typically include replacing the faulty rollover sensor, repairing or replacing any damaged wiring or connectors, and potentially resetting or replacing the airbag control module if it is found to be defective.
6. Is it safe to drive with the B3856 code active?
Driving with the B3856 code active is not recommended as it implies a critical safety feature related to rollover accidents may not function properly, potentially increasing the risk of injury in an accident.
7. Can the B3856 code affect the vehicle’s handling or performance?
While the B3856 code primarily affects the rollover sensor, it should not impact the vehicle's general handling or performance. However, safety features related to rollover protection may be compromised.
8. What tools are needed to confirm the B3856 code?
Confirming the B3856 code requires a diagnostic scan tool capable of reading chassis codes, a multimeter for electrical testing, and possibly an oscilloscope to further analyze sensor output.
9. How often does the B3856 code occur in vehicles?
The occurrence of code B3856 is not very common and typically depends on the vehicle's condition, age, and exposure to harsh driving conditions that might affect the sensor or associated wiring.
10. What is the cost implication of resolving the B3856 code?
The cost to resolve the B3856 code can vary widely. Expenses may include the cost of a new sensor, which can range from $100 to $300, plus labor costs depending on the vehicle make and model and the complexity of the sensor installation.
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