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DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B0077

B0077Driver Seatbelt Pretensioner Resistance High

B0077 indicates that the restraint control module has measured excessive resistance in the driver seatbelt pretensioner circuit, which is the pyrotechnic device that retracts the belt during a crash. The module monitors the circuit's resistance and flags this code when the reading exceeds the expected range, typically due to a poor connection, damaged wiring, or an open squib.

SystemBody
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

  • The airbag or supplemental restraint system warning light is illuminated on the dashboard.
  • Often no symptoms besides the warning light, as the pretensioner only activates during a collision.
  • The seatbelt may not lock or retract as designed in a crash, compromising occupant restraint.
  • In some vehicles, other restraint system functions may be disabled or the airbag light may flash.
  • Intermittent warning light operation if the fault is a loose connection or chafed wire.

Common causes, most likely first

  1. Corroded, loose, or disconnected electrical connector at the pretensioner or under the seat.
  2. Damaged or chafed wiring harness in the seat track area or door sill, often from seat movement or debris.
  3. Open circuit in the pretensioner squib (the pyrotechnic element) due to internal failure or prior deployment.
  4. Poor terminal tension or pin fit at the restraint control module connector.
  5. Water intrusion or corrosion in the connector or wiring, especially in vehicles with sunroof drains or leaky seals.
  6. Aftermarket accessories or seat covers that interfere with the pretensioner wiring or connector.

How to diagnose and fix it

  1. Inspect the pretensioner connector under the driver seat for corrosion, looseness, or damage; clean and reseat as needed.
  2. Check the wiring harness along the seat track and sill for chafing, cuts, or pinches; repair any damaged wires.
  3. Measure resistance across the pretensioner squib with a digital multimeter (after disabling the SRS system) to compare with specification.
  4. Perform a wiggle test on the harness and connectors while monitoring resistance to identify intermittent faults.
  5. Check for technical service bulletins (TSBs) or recalls related to the pretensioner circuit for the specific vehicle.
  6. If resistance is out of range and wiring is good, replace the pretensioner assembly as a complete unit.
  7. Clear the code and verify the repair with a scan tool; ensure the SRS light extinguishes and no codes return.

Before you replace the pretensioner

  • A common oversight is a loose or corroded connector under the seat, often caused by seat movement or spilled liquids, which can mimic a failed pretensioner.
  • The code can be set by a poor connection at the restraint control module itself, so always check both ends of the circuit before condemning the pretensioner.
  • After any collision repair or seat removal, the pretensioner connector may not be fully latched, triggering this code even though the component is functional.
  • Some vehicles require the battery to be disconnected and the SRS system to be de-energized for several minutes before working on the pretensioner to avoid accidental deployment.
  • A pretensioner that has already deployed will show an open circuit and set this code; always inspect for a deployed mechanism before testing.

Can I keep driving with B0077?

It is not safe to drive with an active B0077 because the driver seatbelt pretensioner may not function in a crash, increasing injury risk. Have the vehicle diagnosed and repaired by a qualified technician before driving, and avoid any impact to the seat or wiring in the meantime.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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