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Knorr-Bremse Group
PD-203-500
Doc. No. Y250905 (EN - Rev. 000)
July 2016
The information contained herein is subject to alteration without notice and therefore may not be the latest release. Please check our website www.knorr-bremseCVS.com for the latest update or contact your local Knorr-Bremse representative.
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KB4TA D System Overview
C o m m e r c i a l V e h i c l e S y s t e m s
Error Detection
The KB4TA D ECU contains self-testing diagnostic circuitry that monitors the ABS components and wiring. When
the ECU senses an erroneous system condition, it activates the trailer ABS warning lamp in the towing vehicle (and
headboard if installed), disables all or part of the ABS functions and stores the error in memory as a Diagnostic
Trouble Code (DTC).
For some trouble codes, the KB4TA D ECU will automatically reset and clear the “active” DTC once the error has
been corrected. When an “active” DTC is cleared automatically, the error remains stored in memory as an „inactive“
DTC and can be viewed using blink code diagnostics or ECU
talk
®. However repeated occurrences of certain errors
will result in the DTC being “latched” which means the error remains “active” even if the condition is only intermittent.
Once the code is latched, a manual reset will be necessary. After the problem is resolved, trouble codes can be
deleted using the diagnostic tool ECU
talk
®
.
ABS Shutdown
Depending on the detected error and the ABS configuration the ECU will either partially or totally disable the ABS
function as follows:
• 2S/2M configurations: total shut down.
• 4S/2M configurations: Reduce to 2S/2M
• 4S/3M configurations: Reduce to 2S/2M.
The above shutdown modes are dependent on the type and location of the detected error. For more information see
ABS Electronics Information Document
Y023867
. In all cases a warning signal will be transmitted to illuminate the
trailer ABS warning lamp which will remain “ON” as long as the ignition is in the “RUN” position. In cases where the
ABS is completely disabled, the vehicle reverts to normal braking (without ABS intervention).
ABS faults should be rectified at the earliest opportunity.
ECU Errors
If an ECU related problem is detected the ABS function is disabled while normal brake control remains available.
Low and High Voltage Operation
Should the supply voltage to the ECU be outside the defined voltage range (18 to 32V) the ABS function is disabled
while normal brake control remains available.
For further information on diagnostics see PD-203-390, Document No. Y250910.
Y026787: 006: EN: Released: Fri Nov 11 11:18:50 CET 2016:
