Mitsubishi 1992 3000GT, Service Manual

Page: 833 / 1308

SERVICE BRAKES
Troubleshooting Anti-lock Braking System Troubleshooting
Symptom
Probable cause
Remedy
Squealing noise when Disc brakes rusted, stuck
brakes are not applied
Lubricate or replace
Loose or extra brake parts
Retighten
Improper positioning of pads in caliper Correct
Improper installation of support mounting to caliper Correct
body
Poor return of brake booster or master cylinder
Replace
Incorrect adjustment of brake pedal or booster Adjust
push-rod setting
Groaning, clicking or Stones or foreign material trapped inside wheel Remove stones, etc.
rattling noise when covers
brakes are not applied
Loose wheel nuts
Retighten
Disc brakes -failure of anti-rattle shim
Replace
Disc brakes loose installation bolt
Retighten
Incorrect adjustment of brake pedal or booster Adjust
push-rod setting.
to 1995 models>
PARTICULAR PHENOMENA OF THE
ANTI-LOCK BRAKING SYSTEM
Models equipped with the anti-lock braking system
(ABS) may exhibit one or more of the following
phenomena from time to time, but none of these
are abnormal.’
(1) A pulsing feeling in the brake pedal, or vibration
of the body or the steering wheel, when the
anti-lock braking system is activated by sudden
braking or by braking on a slippery road surface.
Actually, this phenomenon is an indication that
the anti-lock braking system is functioning nor-
mally.
(2) When the vehicle speed reaches approximately
6 km/h (4 mph) after the engine is started and
the vehicle starts off (for the first time), a whining
motor noise may be heard from the engine
compartment if the vehicle is traveling in a quiet
place, but this noise is simply the result of a
self-check being made of the anti-lock braking
system operation.
TROUBLESHOOTING METHODS
Problems related to the anti-lock braking system
(ABS) can be classified into two general categories:
problems in the electrical system and those in the
hydraulic system.
For problems in the electrical system, the on-board
diagnostic is built into the electronic control unit
(ECU) causing the ABS warning light to illuminate
as a warning to the driver. In this instance, checks
can be made by using the multi-use tester and
oscilloscope.
Problems in the hydraulic system (poor, braking,
etc.) can be located in the same way as for ordinary
brakes. There is, however, the necessity to check
to determine whether the problem is related to ordi-
nary brake components or to the components re-
lated to the ABS. To make this check, use the
scan tool.
HOW TO USE THE
TROUBLESHOOTING FLOW CHART
(1) Using the flow chart, check the ABS warning
light light-up sequence. Read the diagnosis
codes and check the condition of braking opera-
tion.
(2) Following the check chart listed in the remedy
column, perform the checks. There are [Ex-
planation] and [Hint] in each check chart. Refer
to them when troubleshooting.
NOTE
ECU: Electronic control unit
HU: Hydraulic unit
TSB Revision