What Does B0078 Mean?
This code indicates that the Body Control Module (BCM) or Restraint Control Module (RCM) has detected a fault in the third row right seatbelt pretensioner deployment circuit. The pretensioner is designed to tighten the seatbelt during a collision, and this subfault suggests an electrical or mechanical issue preventing proper deployment control. The system has identified a specific problem within the pretensioner circuit that could compromise occupant safety during a crash.
Safety Warning
This is a critical safety system fault that compromises occupant protection in the event of a collision. The affected seatbelt pretensioner may not deploy properly during a crash, potentially resulting in serious injury. Vehicle should be repaired immediately and occupants should avoid using the third row right seat until repaired.
Common Causes
35%
Faulty seatbelt pretensioner assembly or internal resistance out of specification
30%
Damaged wiring harness or connector corrosion between BCM/RCM and pretensioner
20%
Poor ground connection or open circuit in pretensioner deployment circuit
15%
Faulty Body Control Module or Restraint Control Module
Diagnostic Steps
1
Step 1: Perform visual inspection of the third row right seatbelt pretensioner assembly and connector for physical damage, corrosion, or water intrusion. Check connector pins for bent, pushed back, or corroded terminals.
2
Step 2: Measure resistance of the pretensioner squib circuit using a digital multimeter (typical specification: 2-3 ohms). Disconnect the pretensioner connector and measure across the pretensioner terminals. Compare reading to manufacturer specifications.
3
Step 3: Check continuity and resistance of the wiring harness from the BCM/RCM connector to the pretensioner connector. Verify no opens, shorts to ground, or shorts to power exist in the circuit (typically requires less than 5 ohms total circuit resistance).
4
Step 4: Inspect and test the ground circuit for the pretensioner system. Verify ground connection integrity and measure voltage drop (should be less than 0.1 volts with circuit energized).
5
Step 5: If all wiring and connections test within specification, monitor live data for pretensioner circuit voltage and deployment readiness status while wiggling harnesses to identify intermittent faults.
6
Step 6: Clear codes and perform system self-test function if available. If code returns immediately with known-good wiring and pretensioner resistance within spec, suspect BCM/RCM internal fault requiring module replacement or professional diagnosis.
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) or Restraint Control Module (RCM) has detected a fault in the third row right seatbelt pretensioner deployment circuit. The pretensioner is designed to tighten the seatbelt during a collision, and this subfault suggests an electrical or mechanic...
The most common cause of B0078 (Third Row Right Seatbelt Pretensioner Deployment Control (Subfault)) is: Faulty seatbelt pretensioner assembly or internal resistance out of specification
Typical repair costs for B0078 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This is a critical safety system fault that compromises occupant protection in the event of a collision. The affected seatbelt pretensioner may not deploy properly during a crash, potentially resulting in serious injury. Vehicle should be repaired immediately and occupants should avoid using the third row right seat until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B0078 to identify the root cause.
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Quick Info
Category
Body
System
Supplemental Restraint System (SRS) / Seatbelt Pretensioner
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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