Abs Electronic Diagnosis; Abs Self-Diagnosis; Drive-Off Cycle; Ongoing Tests - Chrysler 2000 LHS Owner's Manual

5 - 66 BRAKES
DIAGNOSIS AND TESTING (Continued)
to cause the ABS to cycle. Again accelerate the vehi-
cle past 40 kph (25 mph). Refer to the diagnostic
manual for further testing of the antilock brake sys-
tem.

ABS ELECTRONIC DIAGNOSIS

The following information is presented to give the
technician a general background on the diagnostic
capabilities of the ABS system. Complete electronic
diagnosis of the ABS system used on this vehicle is
covered in the ITT Teves Mark 20 Antilock Brake
System diagnostics manual.
Electronic diagnosis of the ABS used on this vehicle
is performed using the DRB scan tool. The vehicle's
scan tool diagnostic connector is located under the
instrument panel, near the steering column (Fig. 11).
Fig. 11 ABS System Diagnostic Connector Location
1 – JUNCTION BLOCK
2 – STEERING WHEEL
3 – DATA LINK CONNECTOR
4 – PARKING BRAKE

ABS SELF-DIAGNOSIS

The ABS system is equipped with a self-diagnosis
capability, which may be used to assist in the isola-
tion of ABS faults. The features are described below.
START-UP CYCLE
The self-diagnosis ABS start-up cycle begins when
the ignition switch is turned to the ON position.
Electrical checks are completed on ABS components,
including the CAB, solenoid continuity, and the relay
system operation. During this check the amber ABS
warning lamp is turned on for approximately 5 sec-
onds and the brake pedal may emit a popping sound,
moving slightly when the solenoid valves are
checked.

DRIVE-OFF CYCLE

The first time the vehicle is set in motion after an
ignition off/on cycle, the drive-off cycle occurs. This
cycle is performed when the vehicle reaches a speed
of approximately 25 kph (15 mph.).
• The pump/motor is briefly activated to verify
function. When the pump/motor is briefly activated, a
whirling or buzzing sound may be heard by the
driver. This sound is normal, indicating the pump/
motor is running.
• The wheel speed sensor output correct operating
range is verified.

ONGOING TESTS

While the system is operating, these tests are per-
formed on a continuous basis:
• solenoid continuity
• wheel speed sensor continuity
• wheel speed sensor output
• system voltage
• CAB self-diagnosis
• PCI communication circuit - sending/receiving
messages
DIAGNOSTIC TROUBLE CODES (DTC's)
Diagnostic trouble codes (DTC's) are kept in the
controller's memory until either erased by the techni-
cian using the DRB, or erased automatically after
3500 miles. DTC's are retained by the controller even
if the ignition is turned off or the battery is discon-
nected. More than one DTC can be stored at a time.
When accessed, the number of occurrences and the
DTC that is stored are displayed. Most functions of
the CAB and the ABS system can be accessed by the
technician for testing and diagnostic purposes using
the DRB.
LATCHING VERSUS NON-LATCHING DIAGNOSTIC TROUBLE
CODES
Some DTC's detected by the CAB are "latching"
codes. The DTC is latched and ABS braking is dis-
abled until the ignition switch is reset. Thus, ABS
braking is non-operational even if the original DTC
has disappeared. Other DTC's are non-latching. Any
warning lamps that are turned on are only turned on
as long as the DTC condition exists; as soon as the
condition goes away, the amber ABS warning lamp is
turned off, although, in most cases, a DTC is set.
INTERMITTENT DIAGNOSTIC TROUBLE CODES
As with virtually any electronic system, intermit-
tent electrical problems in the ABS system may be
difficult to accurately diagnose. Most intermittent
electrical problems are caused by faulty electrical
connections or wiring. A visual inspection should be
done before trying to diagnose or service the antilock
brake system; this will eliminate unnecessary diag-
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