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
- The brake pump motor relay or fuse
- The relay connector or wiring
- A brake fluid leak inside the brake actuator (per Toyota bulletins for the Prius and Highlander Hybrid)
What you can do yourself
- If the brake pedal has become hard, soft or sinks, or the car brakes worse — don’t drive, call a tow truck.
- Check the brake pump motor fuse and relay.
- Check the brake fluid level in the reservoir.
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.
A code of brakes with a pump and a hydraulic accumulator (as given in the 4Runner 1996–2002 manual and Toyota bulletins for the Prius and Highlander Hybrid). 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; Toyota T-SB-0032-16, T-SB-0079-18 (static.nhtsa.gov)
The explanation comes from the error code reference in the AvtoElektrik PRO app.