B0078
Third Row Right Seat Belt Pretensioner Deployment Control.
- Generic
- Body
- Generic code
- High severity
How this code is built
- B
- SystemBody
- 0
- Defined bySAE, the same on every car
- 0
- AreaBody area 0
- 78
- FaultThe specific fault in that area
What it means
B0078 is a generic body code relating to the third row right seat belt pretensioner deployment control circuit in the supplemental restraint system (SRS). The restraint control module monitors the squib circuit and has detected a fault, such as abnormal resistance, an open or short circuit, or a communication problem. The exact fault criteria and the terminology used vary by manufacturer and model, and not every vehicle has third row seating with pretensioners.
Symptoms
- Airbag or SRS warning light on the dashboard
- Warning light stays on after starting and does not clear
- Possible message on the dashboard about a restraint system fault
- Third row right belt pretensioner may not deploy in a crash
- Other SRS codes stored at the same time
Possible causes
- Damaged, loose or corroded connector at the third row right seat belt pretensioner, often disturbed by seat folding or removallikely
- Damaged wiring or yellow SRS harness to the pretensioner, for example chafing, pinching or an open circuit near the seat or trimlikely
- Fault in the pretensioner (squib) itself, giving out-of-range resistancepossible
- Poor connection at an inline SRS connector or shorting bar between the module and the pretensionerpossible
- Water ingress or corrosion in the rear floor or quarter trim area affecting the circuitpossible
- Fault in the restraint control modulerare
- Previous collision damage or incorrect repair of the belt or harnessrare
How to diagnose
- Read all stored codes and freeze frame data, noting whether the fault is current or historic and whether other SRS codes are present
- Ask about recent work, such as seat removal, trim removal, or crash repair, as this often points to a disturbed connector
- Visually inspect the third row right seat belt pretensioner connector, harness routing and trim for damage, pinching, corrosion or water
- Check for any inline SRS connectors along the harness and make sure they are fully seated and the locking clips are intact
- Following the manufacturer procedure, which includes disconnecting the battery and waiting the specified time, test the circuit resistance and check for shorts to ground or voltage
- Check the live data for the pretensioner circuit status where the system supports it
- Check the manufacturer service information for model-specific diagnostic steps and whether the vehicle actually has a third row pretensioner circuit
- Clear the code after repair and confirm it does not return
How to fix
- Repair or replace damaged wiring in the pretensioner circuit using the manufacturer approved method
- Refit, clean or replace corroded or damaged connectors
- Replace the faulty seat belt pretensioner assembly if the circuit tests point to the unit
- Dry out and cure any water ingress source, then repair affected circuits
- Replace or repair the restraint control module only if testing confirms it is faulty, and carry out any required setup procedure
Can I keep driving?
The car will usually still drive, but the right third row belt pretensioner may not work in a collision, so avoid carrying passengers in that seat until repaired. Have the SRS system inspected promptly by a qualified technician.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.