The abs and traction actuator turns off the solenoids and the ecm shuts off vsc control (traction control signal) from the skid control ecu accordingly, the result being that it is as if the abs, trc and vsc systems were not installed.
If it is impossible to control the systems, the warning light comes on to inform the driver of malfunctions in the systems (see page bc-44).
Hint:

Freeze frame data
Data list / active testIf you think
something is wrong
If you notice any of the following symptoms, your vehicle probably
needs adjustment or repair. Contact your toyota dealer as
soon as possible.
Visible symptoms
Fluid leaks under the vehicle
(water dripping from the air conditioning after use is normal.)
Flat-looking tires or uneven tire w ...
Operation check
Inspect driver side seat belt warning light
Turn the ignition switch on.
When the driver seat belt is not fastened, check that
the driver seat belt warning light on the combination
meter blinks.
When the driver seat belt is fastened, check that the
driver seat belt warning light o ...
How to proceed with troubleshooting
Hint:
Use these procedures to troubleshoot the tire pressure
warning system.
*: Use the intelligent tester.
Vehicle brought to workshop
Inspect battery voltage
Standard voltage:
11 to 14 v
If the voltage is below 11 v, recharge or replace the battery
before proceeding.
...