PREVOST X3-45 Multiplex, Maintenance Manual

Page: 591 / 1422

17
REVISED 5/31/05
Active Diagnostic Trouble Code Mode
For troubleshooting, typically the Active and Inactive
Diagnostic Trouble Retrieval Modes are used. The
technician presses the blink code switch once and the ABS
indicator lamp flashes a first group of two codes, and if
there are more trouble codes recorded, this is followed by
a second set of codes, etc. (See page 21 for a directory of
these codes.) All active trouble codes may also be retrieved
using a hand-held or PC-based diagnostic tool, such as
the Bendix
®
ACom
™
Diagnostics software.
To clear active diagnostic trouble codes (as problems
are fixed), simply clear (or “self-heal”) by removing and
re-applying ignition power. The only exception is for wheel
speed sensor trouble codes, which clear when power is
removed, re-applied, and the ECU detects valid wheel
speed from all wheel speed sensors. Alternately, codes
may be cleared by pressing the diagnostic blink code switch
3 times (to enter the Clear Active Diagnostic Trouble Code
Mode) or by using a hand-held or PC-based diagnostic
tool. Hand-held or PC-based diagnostic tools are able to
clear wheel speed sensor trouble codes without the vehicle
being driven.
Inactive Diagnostic Trouble Code Mode
The ECU stores past trouble codes and comments (such
as configuration changes) in its memory. This record is
commonly referred to as “event history.” When an active
trouble code is cleared, the ECU stores it in the event
history memory as an inactive trouble code.
DIAGNOSTIC MODES
In order to communicate with the ECU, the controller has
several modes that the technician can select, allowing
information to be retrieved, or other ECU functions to be
accessed.
Diagnostic Modes
To enter the various diagnostic modes:
Blink Code Timing
The ECU responds with a sequence of blink codes. The
overall blink code response from the ECU is called a
“message.” Each message includes, depending on the
mode selected by the technician, a sequence of one or
more groups of blinks. Simply record the number of blinks
for each sequence and then use the troubleshooting index
on page 21 for active or inactive trouble codes and you
will be directed to the page that provides troubleshooting
information.
NOTE:
1. Sequences of blinks illuminate the ABS indicator lamp
for half a second, with half-second pauses between
them.
2. Pauses between blink code digits are 1.5 seconds.
3. Pauses between blink code messages are 2.5
seconds.
4. The lamp remains on for 5 seconds at the end of
messages.
Once the ABS indicator lamp begins displaying a sequence
of codes, it continues until all blink code messages have
been displayed and then returns to the normal operating
mode. During this time, the ECU will ignore any additional
blink code switch activation.
All trouble codes, with the exception of voltage and
J1939 trouble codes, will remain in an active state for the
remainder of the power cycle.
Voltage trouble codes will clear automatically when the
voltage returns within the required limits. All ABS functions
will be re-engaged.
J1939 trouble codes will clear automatically when
communications are re-established.
* To enter the Reconfiguration Mode, the switch must
be held in before the application of ignition power.
Once the power is supplied, the switch is released
and then pressed seven times.
No. of Times to
Press the Blink
System Mode Entered
Code Switch
1 Active diagnostic trouble code retrieval
2 Inactive diagnostic trouble code retrieval
3 Clear active diagnostic trouble codes
4 System configuration check
5 Dynamometer Test Mode
7* Reconfigure ECU
CHART 2 - DIAGNOSTIC MODES