Mitsubishi ECLIPSE Technical Information Manual

DRIVE-CONTROL COMPONENTS - ABS <FWD>
DIAGNOSIS OF THE WHEEL SPEED SENSOR SYSTEM
L
On-board diagnosis of the wheel speed sensor sys- is detectable only when the vehicle is put into
tern is accomplished by executing the diagnostic
motion or when it is running.
program stored in the computer. U&g the program,
the ABS-ECU monitors each wheel speed sensor
system (wheel speed sensor, rotor, etc.) to detect
a failure. In addition, the ABS-ECU monitors a short
or open circuit in the sensor system by using its
voltage monitoring circuit and voltage monitoring
program.
The former is called “software failure detection”,
whereas the latter is called “hardware failure detec-
tion”.
(1) Software failure detection
In this diagnostic test mode, the speeds of the
four wheels calculated from the sensor outputs
are compared. If there is any sensor system
that outputs an abnormal speed or an abnormal
decelerated speed, the ABS-ECU determines
that the system is out of order. Such a failure
FAIL-SAFE FUNCTION
Should a failure occur in the ABS system, the ABS-
ECU isolates the system to retain the vehicle’s ordi-
nary braking function, thus assuring a high measure
of safety.
L
l If the ABS-ECU determines that the system
is defective as the result of diagnosis, it causes
DIAGNOSTIC FUNCTIONS
To facilitate inspection of the ABS system, the ABS-
ECU offers the following facilities:
l Diagnostic trouble code output and erasure
l Data list output
l Actuator tests
All of the items described above can be checked
by the scan tool.
Scan Tool -
ABS Interface
The scan tool function is entered by connecting
the scan tool to the data link connector. At this time,
(2) Hardware failure detection
The ABS-ECU monitors the sensors, harness,
etc. by using its open/short circuit monitoring
circuit and voltage monitoring program to detect
a failure such as an open or short circuit. A
major feature of the open/short circuit monitoring
circuit is that an open or short circuit failure
is always detectable (even when the vehicle
is stationary).
When the vehicle is in motion, however, a failure
may be detected by software failure detection
function before the same open or short circuit
failure is detected by the hardware failure detec-
tion function. Such a situation may occur de-
pending on the condition of vehicle and the
nature of the failure.
the ABS warning light to light, drives the valve
relay to interrupt control of the solenoid valves
in the HU, and restores the ordinary braking
mode.
the vehicle must be stopped, and the ignition should
be OFF.
The ABS scan tool mode is entered when you select
the ABS system on the scan tool. In this mode,
diagnostic output, data list output and actuator test
functions are available. During an actuator test, how-
ever, the ABS warning light illuminates and anti-lock
control is inhibited to prevent ABS operation when
a brake is temporarily inactivated during the actuator
test.
Scan tool
0 Wheel speeds of 0 km/h (0 mph), parked condi-
mode entry
tion
condition
0 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)
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)]

Mitsubishi ECLIPSE Specifications

General

Brand	Mitsubishi
Model	ECLIPSE
Category	Automobile
Language	English