The following warning indicates a possible problem in the brake system.
Immediately stop the vehicle in a safe place and contact your Toyota dealer.

If a warning light turns on or a warning buzzer sounds...
Stop the vehicle immediately.Security Horn Circuit
DESCRIPTION
When the theft deterrent system is switched from the armed state to the alarm
sounding state, the main body ECU (driver side junction block assembly) controls
the security horn.
WIRING DIAGRAM
PROCEDURE
1.
PERFORM A ...
Precaution
PRECAUTION
NOTICE:
When disconnecting the cable from the negative (-) battery terminal, initialize
the following systems after the cable is reconnected.
System Name
See Procedure
Back Door Closer System
...
On-vehicle Inspection
ON-VEHICLE INSPECTION
PROCEDURE
1. INSPECT COMPRESSOR FOR METALLIC SOUND
(a) Check if there is abnormal metallic sound from the A/C compressor (compressor
with pulley) when the A/C switch is on and the A/C compressor (compressor with pulley)
operates.
...