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GENERAL INFORMATION
3.2.1 ABS INITIALIZATION
System initialization starts when the key is
turned to ''run''. At this point, the CAB performs a
complete self-check of all electrical components in
the antilock brake systems.
At 20 km/h (12 mph) a dynamic test may be
performed. If the brake lamp switch is activated the
test will be run at 40 km/h (24 mph) regardless of
the brake lamp switch state. This will momentarily
run the pump/motor. If during the dynamic test, the
driver has his/her foot on the brake pedal, he/she
may feel the test through brake pedal pulsations.
This is a normal condition.
If any component causes a diagnostic trouble code
during system initialization or dynamic check, the
CAB will request the ABS indicator to illuminate.
3.2.2 DIAGNOSTIC MODE
For a Mark 20e system to enter a diagnostic
mode, vehicle speed must be below 10 km/h (6 mph)
and no ABS condition present. If vehicle speed is
not below 10 km/h (6 mph), a ''No Response'' mes-
sage could be displayed by the DRBIII . The follow-
ing are characteristics of diagnostic mode:
•
The amber ABS warning indicator will blink
rapidly. If a hard trouble code is present, such as
a CAB Power Feed Circuit diagnostic trouble
code, the ABS warning indicator will be illumi-
nated without blinking until the diagnostic trou-
ble code condition is corrected.
•
Antilock operation is disabled.
3.2.3 INTERMITTENT DIAGNOSTIC
TROUBLE CODES
If the malfunction is not present while perform-
ing a test procedure, the diagnostic procedures will
not locate the problem. In this case, the code can
only suggest an area to inspect. Check for the
following:
•
mechanical interference with brake or accelera-
tor pedal
•
loose or corroded conditions
•
damaged components (sensors, tone wheels,
pedal drive cable)
•
damaged wiring
•
excessive axle shaft runout
•
loose pedal mounting
•
hydraulic system leaks
•
regular brake system problems, non-ABS related
If no obvious problems are found, erase diagnostic
trouble codes and with the key on, wiggle the wire
harness and connectors. Recheck for codes periodi-
cally as you work through the system. This proce-
dure may uncover a difficult to locate malfunction.
3.3 FREEZE FRAME
Freeze Frame takes a ''snapshot'' of specific vehi-
cle information the instant an ABS failure is recog-
nized and stores this information into the CAB
memory. This information can be accessed using the
DRBIII to help diagnose the fault. Freeze Frame
will capture the first time failure or only a new
failure that occurs during the current ignition cycle.
3.4 USING THE DRBIII
Refer to the DRBIII user's guide for instructions
and assistance with reading diagnostic trouble
codes, erasing diagnostic trouble codes and other
DRBIII functions.
3.5 DRBIII ERROR MESSAGES
Under normal operation, the DRBIII will dis-
play one of only two error messages:
—
User-Requested
Requested COLD Boot
If the DRBIII
should display any other error
message, record the entire display and call the
STAR Center for information and assistance. This
is a sample of such an error message display:
ver: 2.14
date: 26 Jul93
file: key_itf.cc
date: Jul 26 1993
line: 548
err: 0x1
User-Requested COLD Boot
Press MORE to switch between this display
and the application screen.
Press F4 when done noting information.
3.5.1 DRBIII DOES NOT POWER UP
(BLANK SCREEN)
If the LED's do not light or no sound is emitted at
start up, check for loose cable connections or a bad
cable. Check the vehicle battery voltage (data link
16-way connector cavity 16). A minimum of 11 volts
is required to adequately power the DRBIII . Also
check for a good ground at the DLC.
If all connections are proper between the
DRBIII and the vehicle or other devices, and the
vehicle battery is fully charged, an inoperative
DRBIII may be the result of faulty cable or vehicle
wiring.
4
WARM
Boot
or
User-
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