Dodge Neon 2001, Руководство по обслуживанию

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TIRE NOISE AND MARKS
Although the ABS system prevents complete wheel
lockup, some wheel slip is desired in order to achieve
optimum braking performance. Wheel slip is defined
as follows: 0 percent slip means the wheel is rolling
freely and 100 percent slip means the wheel is fully
locked. During brake pressure modulation, wheel slip
is allowed to reach up to 25–30 percent. This means
that the wheel rolling velocity is 25–30 percent less
than that of a free rolling wheel at a given vehicle
speed. This slip may result in some tire chirping,
depending on the road surface. This sound should not
be interpreted as total wheel lockup.
Complete wheel lockup normally leaves black tire
marks on dry pavement. The ABS will not leave dark
black tire marks since the wheel never reaches a
fully locked condition. However, tire marks may be
noticeable as light patched marks.
START-UP CYCLE
When the ignition is turned on, a popping sound
and a slight brake pedal movement may be noticed.
The ABS warning indicator lamp will also be on for
up to 5 seconds after the ignition is turned on. These
conditions occur as part of an ABS self-diagnosis test
performed by the antilock brake system. The popping
noise is the result of brief activation of the solenoids
inside the integrated control unit (ICU).
DRIVE-OFF CYCLE
When the vehicle is first driven off, a humming
may be heard or felt by the driver at approximately
25–40 km/h (15–25 mph). This is caused by brief acti-
vation of the ABS pump motor on the ICU and is a
normal function of ABS as the system is performing
a diagnosis check.
PREMATURE ABS CYCLING
Symptoms of premature ABS cycling include: click-
ing sounds from the solenoid valves; pump/motor
running; and pulsations in the brake pedal. Prema-
ture ABS cycling can occur at any braking rate of the
vehicle and on any type of road surface. Neither the
red BRAKE warning indicator lamp, nor the amber
ABS warning indicator lamp, illuminate and no fault
codes are stored in the controller antilock brake
(CAB).
Premature ABS cycling is a condition that needs to
be correctly assessed when diagnosing problems with
the antilock brake system. It may be necessary to use
a DRBIII
t
scan tool to detect and verify premature
ABS cycling.
Check the following common causes when diagnos-
ing premature ABS cycling: damaged tone wheels;
incorrect tone wheels; damaged steering knuckle
wheel speed sensor mounting bosses; loose wheel
speed sensor mounting bolts; excessive tone wheel
runout; excessively large tone wheel-to-wheel speed
sensor air gap, or a damaged speed sensor head face.
Give special attention to these components when
diagnosing
a vehicle exhibiting premature ABS
cycling.
After diagnosing the defective component, repair or
replace it as required. When the component repair or
replacement is completed, test drive the vehicle to
verify that premature ABS cycling has been cor-
rected.
DIAGNOSIS AND TESTING - INSPECTION AND
ROAD TEST
(1) Visually inspect the ABS for damaged or dis-
connected components and connectors.
(2) Verify the brake lamps are operational. If they
are not, repair them prior to continuing.
(3) Connect the DRBIII
t
scan tool to the Data
Link Connector located under the instrument panel
to the left of the steering column (Fig. 1). If the
DRBIII
t
does not power-up, check the power and
ground supplies to the connector.
(4) Turn the ignition key to the ON position. Select
ANTILOCK BRAKES.
(5) Read and record any Diagnostic Trouble Codes
(DTCs). If any DTCs are present, refer to the appro-
priate chassis diagnostic information.
Fig. 1 Diagnostic Data Link Connector Location
1 - DRIVER AIRBAG
2 - PASSENGER AIRBAG
3 - DATA LINK CONNECTOR
5s - 28 BRAKES-ABS
PL
BRAKES-ABS (Continued)
ProCarManuals.com
2001 NEON