B1903 LEXUS, SCION, TOYOTA: SHORT TO POSITIVE IN FRONT DRIVER SIDE PRETENSIONER SQUIB CIRCUIT
POST UPDATED IN May, 2023
B1903 Code failures by brands
Description of DTC code B1903
The circuit that activates the front pretensioner on the driver’s side includes the center airbag sensor and the outside left belt corresponding to the front seat (LH). The function of this ignition circuit is to command the SRS (Supplemental Restraint System) to initiate deployment once the conditions for deployment are met.
In case the driver’s side front pretensioner activation circuit does not work properly, specifically a positive short circuit, the DTC B1903 OBDII code will be set for Lexus, Scion, Toyota vehicles.
Symptoms of fault code B1903
- Check Engine light is ON.
- The airbag light remains ON.
Causes of OBD2 B1903
Reasons for setting the B1903 OBD2 fault code B1903:
- The wiring of the front seat outer left seat belt circuit may be faulty.
- Possibly the left front seat outer belt (front driver's side pretensioner squib) is in poor condition.
- The center airbag sensor assembly may be damaged.
Possible solutions of the DTC code B1903
To troubleshoot the B1903 OBD2 diagnostic code, please note this:
- First, consult the TSBs.
- Check all the wires related to the front seat outer left seat belt circuit, and check for common damage. If you find remarkable deficiencies causing the short, proceed with repairs.
- Read the voltages of the front seat outer left seat belt circuit, and check that these values match those indicated by the manufacturer. If one of the voltages is not within the proper parameters, make the appropriate corrections.
- By using the manufacturer's recommended diagnostic steps, verify that the center airbag sensor assembly and the left front outboard front seat belt are in good condition. If you find deficiencies, make the appropriate adjustments.
