31-3X: Driver Side Airbag Inflator Short

Circuit fault

What 31-3X means

Side airbags on these cars are built into the outboard side of the seat back, and their inflator sits on a monitored loop like every other pyrotechnic device in the system. The SRS unit expects a specific resistance. A reading under that range means current has an extra path, and Acura stores 31-3X for the driver side bag.

The wiring for a seat-mounted bag has a hard life. It has to reach a seat that slides, reclines, and on many cars raises and lowers, so the harness flexes every time somebody adjusts their position. Years of that flexing wear insulation from the inside out, and two conductors in the same loom eventually touch.

Common causes

• Insulation worn through inside the seat harness from years of seat travel
• The under-seat connector crushed or dragged when the seat was moved to its limit
• A spilled drink soaking into the seat cushion and reaching the airbag connector
• Seat heater or power seat wiring added later and rubbing against the SRS pair
• Damage inside the seat back from an aftermarket seat cover installed over the bag

Crash data or hardware fault?

This code reflects a measurement the module takes continuously, so it is a live circuit fault. When the extra path is gone the resistance returns to normal and the code stops being current. Crash data does not behave that way. It is written once when a bag fires and stays in the module permanently until a bench reset removes it.

Does our reset clear it?

Clearing 31-3X on a scan tool does not repair the short. The module retests the loop within seconds of key-on and stores it again. Find the contact point, repair it, then clear. Where our mail-in reset fits is a module that fired and is locked on deployment data, and that service happens after the seat, bag, and wiring work is done.

Which makes throw it

31-3X sits in the Acura portion of our code index. Look the number up against the list that matches the vehicle so the circuit you test is the one the code names.

What to do next

Slide the seat forward and back and watch the harness under it before you take anything apart, since a short that comes and goes with seat position tells you where to look. Unplug the side airbag at the seat back and measure the loop at the seat connector. If the low reading disappears with the bag unplugged, the fault is in the seat harness, and if it follows the bag, the side airbag assembly is the part to replace. Related codes: 22-9X, 31-8X, 00592.