Code B0078 signals a fault in the deployment‑control circuit for the third‑row right seat‑belt pretensioner. The restraint control module has detected an abnormal voltage, resistance, or communication error in the circuit that activates the pretensioner during a crash.
The pretensioner’s internal squib or initiator has an open or shorted circuit, causing the control module to flag a deployment‑control fault.
Damaged harness, corroded pins, or a disconnected connector between the pretensioner and the restraint control module creates an abnormal resistance reading.
The RCM’s output driver that supplies the deployment signal may be damaged, preventing proper voltage delivery to the pretensioner.
Oxidation or mechanical looseness adds resistance, leading the RCM to detect a deployment‑control error.
An outdated or corrupted RCM firmware version can misinterpret normal circuit values as a fault; a reprogram may resolve it.
No. B0078 is a restraint‑system code handled by the restraint control module; the PCM is not involved in pretensioner deployment control.
Yes. Corroded or loose connectors are a common cause; cleaning and reseating them often restores proper circuit resistance and clears the code.
The pretensioner is the most likely failure point, but wiring and RCM driver faults occur nearly as often; systematic testing is required before replacement.
The light will extinguish once the fault is corrected and the code is cleared with a scan tool; it does not self‑clear on most vehicles.