A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- SRS unit internal fault
- The SRS unit after a crash: it must be restored or replaced
- The SRS unit’s power and ground
- Low voltage: a flat battery or corroded terminals
What you can do yourself
- You can drive, but don’t put off the repair: the airbags may not deploy in a crash.
- Don’t test squibs or airbags with a multimeter and don’t take them apart: the airbag can deploy and injure you. Touch the connectors only with the battery terminal disconnected and after waiting several minutes. Don’t fit airbag “emulators”: there will be no protection in a crash.
- Check the battery: with low voltage the SRS unit also stores faults.
- After a crash, deployed airbags and pretensioners are replaced, and the SRS unit is restored or replaced.
- After the repair the code won’t go away by itself: it is cleared with a scan tool.
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
On cars with flash-code self-diagnosis the SRS light shows this code as 31. This is the Toyota and Lexus meaning. On other makes this number means something else: if your car isn’t a Toyota or Lexus, change the make at the top.
Source: Toyota 4Runner 1996–2002 repair manual (ether3al.com)
The explanation comes from the error code reference in the AvtoElektrik PRO app.