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Knorr-Bremse Group
PD-203-400
Doc. No. Y250904 (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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Note: If service work is carried out on a vehicle based on information provided herein, it is the responsibility of the workshop to ensure the vehicle is fully tested and in full
functional order before the vehicle is returned into service. Knorr-Bremse accepts no liability for problems caused as a result of appropriate tests not being carried out.
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KB4TA System Overview
P r o d u c t D a t a
KB4TA System diagram (2S/2M) for semi-trailer with mechanical suspension and drum brakes
11
SE
RVICE
PA
RKING
1
2
11
SER
VICE
PAR
KING
12
11
SE
RVICE
PA
RKING
1
2
11
SER
VICE
PAR
KING
12
sys_dia_002
1
2
3
15
5
6
4
8
14
9
10
7
11
Legend:
1 Coupling Head with Filter -
“Supply”
2 Coupling Head with Filter -
“Control”
3 ABS Connector ISO 7638
4 Park / Shunt Valve with
Emergency Function
5 Air Reservoir
6 Drain Valve
7 Load Sensing Valve
8 ABS Module with 6 delivery
ports
9 Brake Chamber
10 Spring Brake
11 Sensing Ring and Wheel Speed
Sensor
14 Test Connector
15 Electrical Connector “Lighting”
acc. to ISO 1185
Power up Sequence
At power up, the KB4TA module performs a series of self-checks that can assist a technician to determine the ABS
system status and configuration.
Trailer ABS Warning Lamp
At power up (when no faults are detected) the trailer ABS warning lamp in the towing vehicle will turn on for
approximately 2 seconds as a bulb check and then turn off. If a fault has been detected the bulb will remain on. The
same warning lamp sequence is produced by the trailer mounted headboard warning lamp (when installed)
Modulator ‘Chuff Test’ at Power up
At power up, the KB4TA module activates a modulator ‘chuff test’. This electrical and pneumatic ABS modulator test
can help the technician identify problems with modulator installations and/or wiring.
With brake pressure applied, a properly installed modulator will generate five rapid audible ‘chuffs’ of air pressure on
the left internal modulator followed by five ‘chuffs’ on the right modulator. There will then be five further ‘chuffs’ on
the additional axle modulator if fitted .
If the modulator is wired incorrectly, the modulator will only produce one ‘chuff’, or no ‘chuffs’ at all. If a fault is
detected during the modulator ‘chuff test’, compare the wiring and piping to the electrical system schematic and
make any necessary alterations.
System Description
Y026787: 006: EN: Released: Fri Nov 11 11:18:50 CET 2016:
