DRIVE-CONTROL COMPONENTS - ABS
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/ FAIL-SAFE FUNCTION
i Should a failure occur in the ABS system, theABS- it causes the ABS warning light to light, drives
ECU isolates the system to retain the vehicle’s ordi-the valve relay to interrupt control of the solenoid
nary braking function, thus assuring a high measurevalves in the HU, and restores the ordinary brak-
of safety. ing mode.
l If the ABS-ECU determines that the system
is defective as the result of diagnostic test mode,
DIAGNOSTIC FUNCTIONS
To facilitate inspection of the ABS system, the ABS-the vehicle must be stopped, and the ignition should
ECU offers the following facilities: be OFF.
l Diagnostic trouble code output and erasureThe ABS scan tool mode is entered when you select
l Actuator test the ABS system on the scan tool. In this mode,
All of the items described above can be checked
diagnostic output, data list output and actuator test
by the scan tool. functions are available. During an actuator test, how-
Scan Tool- ABS Interface ever, the ABS warning light illuminates and anti-lock
control is inhibited to prevent ABS operation when
The scan tool function is entered by connectinga brake is temporarily inactivated during the actuator
the scan tool to the data link connector. At this time,
Scan tool 0 Wheel speeds of 0 km/h (0 mph), parkedcondi-
mode entry tion
condition Q Check harness of scan tool connected to data
link connector of vehicle
0 ABS system selected by control switch of scan
tool (Specified serial data received)
i NOTE
No communications with the ABS-ECU can be made by con-
necting the scan tool while the vehicle is in operation [wheel
speeds not 0 km/h (0 mph)].