Mitsubishi 1992 3000GT, Service Manual

Page: 854 / 1308

SERVICE BRAKES Anti-lock Braking System Troubleshooting
No.
4
Trouble condition
After the ignition key is turned to the “ON”
position, it blinks once and then illumi-
nates when it is turned to the “START’
position. When the key is returned to the
“ON” position, the light blinks again.
(Blinking with the ignition key in the “ON”
position is synchronized with operation
noise of the valve relay.)
ABS
warning
light
Ignition
ACC,
Major causes
l
Break in harness for ECU warning
light drive circuit
l
Malfunction of ECU
CONTINUED FROM PREVIOUS PAGE
Does the ABS
when starting to drive
Yes
Trouble with the motor relay, solenoid
valve [due to self test at start-up or
function of wheel speed sensor]
No
Is there one-sided braking, insufficient CONTINUED ON NEXT PAGE
braking force or malfunction of ABS op-
eration?
Yes
Trouble condition Major causes
One-sided braking
lnsuff braking force
Decline in ABS function
ABS sometimes functions even when
there is no sudden braking. (ABS opera-
tion vibration is transmitted.)
l
Hydraulic line in HU is clogged.
Mechanical lock of HU solenoid valve
l
Hydraulic line in HU is clogged.
l
Malfunction in HU solenoid valve op-
eration
l
Insufficient wheel speed sensor out-
put voltage (sensor malfunction, too
large a gap between sensor rotor,
missing rotor teeth)
l
Malfunction of ABS ECU
Remedy
Check, using flow
chart D (Refer to
Remedy
Check HU operation and, if
necessary, replace HU. If HU
is normal, check structural
parts for normal braking.
Check wheel speed sensor
(Refer to
and, if nec-
essary, replace sensor, adjust
gap or replace rotor.
If tests indicate that there are
no mechanical or electrical
failures, replace the ECU.
TSB
Revision