3-54
DRIVE-CONTROL
COMPONENTS
-
ABS
<AWD>
INITIAL CHECK FUNCTION
The ECU always performs an initial check on the
ABS system with the on-board diagnostic function.
1. Initial Check Operation
(1) When the ignition key is placed in the ON posi-
tion, the power is supplied to the ABS-ECU,
and the ABS-ECU starts a diagnostic sequence.
During the diagnostic period, the ABS valve
relay stays in the “OFF” state and the warning
light continues to light.
(2) Then, the ABS-ECU forces the ABS valve relay
into the “ON” state and executes diagnostic test
mode of the ABS valve relay to detect an ON
or OFF failure.
(3) All the solenoid valves are caused to be ON
and OFF to make sure that the valves are not
sticking.
If it detects an error, it illuminates the warning light,
and disables the ABS system.
(4) If the engine starts and the ignition key is re-
turned to the “ON” position, the ABS-ECU power
supply is resumed, and initial checks in (1)
through (3) are performed again.
(5) When the initial checks are satisfactorily com-
pleted, the ABS becomes ready for operation.
NOTE
An operation check for the motor relay and the motor
is performed when the vehicle is put in motion after
starting the engine. This check is performed only
once whenever the ignition switch is turned “ON”.
START
Ignition key
ON
ACC
ABS-ECU
power supply
12v
ov
.
..i..
ABS
warning light
ABS valve
ON
relay
Solenoid ON
valve
OFF
14X0243
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