Knorr-Bremse TEBS KB4TA-D User manual

Doc. No. Y364866 (EN - Rev. 000)
March 2020
TEBS KB4TAD
SERVICE MANUAL

2
» Y364866 – (EN - REV. 000) | March 2020
Disclaimer
The information contained in this document is intended for the exclusive use of trained persons within the commercial vehicle industry, and must not be passed on
to any third party. All recommendations regarding products and their servicing or usage are with reference to Knorr-Bremse products and should not be considered
applicable to products from other manufacturers.
This information does not purport to be all-inclusive and no responsibility is assumed as a result of its use. We cannot accept any liability nor oer any guarantee
regarding data accuracy, completeness or timeliness. The information does not represent any guarantee or ensured characteristics of the Products or Systems
described. No liability can be accepted based on the information, its use, recommendations or advice provided. In no event may we be held liable for any damage or
loss except in the case of wilful intent or gross negligence on our part, or if any mandatory legal provisions apply.
Any legal disputes arising from the use of this information shall be subject to German law.
Note: If service work is carried out on the vehicle, 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.
This disclaimer is an English translation of a German text, which should be referred to for all legal purposes.
Revision Details
Rev. 000 Mar. 2020 New document

3
» Service Manual - KB4TA-D
Contents
Safety and Environment Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1 KB4TA-D System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2 System Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.1 Power up Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.2 Trailer ABS Warning Lamp (No Active Fault) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.3 Trailer ABS Warning Lamp (With Active Faults) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.4 Modulator ‘Chu Test’ at Power up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.5 ABS Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2.6 Normal Braking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.2.7 Odometer Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.2.8 Service Interval. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.2.9 ABS Auto Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.2.10 ABS Manual Conguration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.2.11 Auxiliary Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.2.12 Auxiliary Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2 ERROR DETECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
2.1 ABS Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1.1 ECU Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1.2 Low and High Voltage Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3 KB4TA-D ABS ECU. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
3.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.2 Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2.1 ECUs K068353 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2.2 Stop Lamp Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2.3 Stop Lamp Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.3 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4 Label Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4 KB4TA-D System Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
4.1 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.1.1 Coupling Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.1.2 Park / Shunt Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1.3 ABS Modulator Relay Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1.4 Wheel Speed Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.1.5 TABS Bracket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.1.6 Cables for KB4TA-D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4
» Y364866 – (EN - REV. 000) | March 2020
Contents
5 KB4TA -D System Diagnostics And Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
5.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.2 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.2.1 Warning Lamp Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.2.2 Diagnostic Program ECUtalk®. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.2.1 ADL (Auxiliary Design Language) Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.3 Diagnostic Components/Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.3.1 Tools list and UDIF (Universal Diagnostic Interface) Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.3.2 Blink Code Diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.3.3 Diagnostic Trouble Codes (DTCs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
5.3.4 Blink Code Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
5.3.5 Diagnostic Trouble Codes — Blink Code Quick Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
5.3.6 Diagnostic Troubleshooting Flow Charts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5
» Service Manual - KB4TA-D
Contents

6
» Y364866 – (EN - REV. 000) | March 2020
Note: The safety advice listed below is applicable to general service and diagnostic work on braking systems. Also observe any
recommendations from the axle or vehicle manufacturer concerning towing, jacking-up and securing the vehicle.
CAUTION: KNORR-BREMSE IS NOT LIABLE FOR ANY INJURIES OR DAMAGES CAUSED BY IMPROPER USE OF SPECIFIED SERVICE KITS AND/OR
SERVICE TOOLS. FURTHERMORE, MISUSE OF TOOLS OR INCORRECT INSTALLATION OR APPLICATION OF SERVICE KITS MAY RESULT IN DAMAGE OR
POTENTIALLY UNSAFE VEHICLE OPERATIONS. IN THIS CASE, KNORR-BREMSE DOES NOT HAVE ANY WARRANTY OBLIGATIONS.
Before and whilst working on or around compressed air systems and devices, the following precautions should be observed, along with the many
hazard notes contained throughout the document:
1 Always wear safety glasses when working with air pressure.
2 Never exceed the vehicle manufacturer’s recommended air pressures.
3 Never look into air jets or direct them at anyone.
4 Never connect or disconnect a hose or line containing pressure; it may whip as air escapes.
5 When removing or servicing a product, ensure all pressure related to the specic system it is contained in has been depleted to 0 bar. Be aware that if the vehicle
is equipped with an air dryer system, it can also contain air pressure along with its purge reservoir, if tted, even after pressure has been drained from the other
reservoirs.
6 If it is necessary to drain the air pressure from reservoirs, etc., keep away from brake actuator push rods and levers since they may move as system pressure
drops. On vehicles tted with air suspension, it is advised when undertaking such work, to support the chassis from sudden lowering and therefore prevent any
possibility of being trapped between the chassis and axle or ground.
7 Park the vehicle on a level surface, apply the parking brakes, and always chock the wheels as depleting vehicle air system pressure may cause the vehicle to roll.
8 When working under or around the vehicle, and particularly when working in the engine compartment, the engine should be shut o and the battery
disconnected. Where circumstances require that the engine be running, EXTREME CAUTION should be taken to prevent personal injury resulting from contact
with moving, rotating, leaking, heated or electrically charged components. Additionally, it is advisable to place a clear sign on or near the steering wheel advising
that there is work in progress on the vehicle.
9 When working on vehicles equipped with air suspension, to guard against injury due to unexpected downward movement of the chassis caused by sudden
pressure loss in the suspension system, ensure that the vehicle chassis is mechanically supported with a ‘prop’between the chassis and the axle or between the
chassis and the ground.
10 Examine all pipework for signs of kinks, dents, abrasion, drying out or overheating. Be aware that kinks in pipework may result in air pressure being trapped in the
pipework and associated equipment. Replacement hardware, tubing, hose, ttings, etc. must be of equivalent size, type and strength as original equipment and
be designed specically for such applications and systems. Check the attachment of all pipework; it should be installed so that it cannot abrade or be subjected
to excessive heat.
11 Components with stripped threads or damaged/corroded parts must be replaced completely. Do not attempt repairs requiring machining or welding unless
specically stated and approved by the vehicle or component manufacturer.
12 Never attempt to install, remove, disassemble or assemble a device until you have read and thoroughly understood the recommended procedures. Some units
contain powerful springs and injury can result if not properly dismantled and reassembled. Use only the correct tools and observe all precautions pertaining to
use of those tools.
13 Before removing any device note its position and the connections of all pipework so that the replacement/serviced device can be properly installed. Ensure that
adequate support or assistance is provided for the removal/installation of heavy items.
14 Use only genuine replacement parts, components and kits as supplied by Knorr-Bremse or the vehicle manufacturer. Only use the recommended tools as
specied in related Knorr-Bremse instructions.
15 The serviced or replaced product must be checked for correct function and eectiveness.
16 If products have been dismantled, serviced or replaced, whose performance could aect braking performance or system behaviour, this should be checked on
a roller dynamometer. Bear in mind that a lower performance may be experienced during the bedding-in phase if new brake pads/linings and/or brake discs/
drums have been tted.
17 The use of impact screwdrivers or impact wrenches in conjunction with Knorr-Bremse service tools for air disc brakes is not permitted. The service tools are not
designed for such use. It is likely that the tools or the vehicle will be damaged and there is a serious risk of injury – see Caution above.
18 Do not use compressed air to clean the disc brake. Avoid air contamination of brake dust.
19 Prior to returning the vehicle to service, make certain that all components and the complete brake systems are leak free and restored to their proper operating
condition.
Safety and Environment Guidelines

7
» Service Manual - KB4TA-D
Welding
To avoid damage to electronic components when carrying out electrical welding, the following precautions should be observed:
1 In all cases, before starting any electrical welding, remove all connections from any electronic control units or modules, noting their position and the order in
which they are removed.
2 When re-inserting the electrical connectors (in reverse order) it is essential that they are tted to their correct assigned position - if necessary this must be
checked by PC Diagnostics.
Disposal of Waste Equipment by Business Users in the European Union
This symbol on the product, packaging or in user instructions, indicates that this product must not be disposed of with other general waste. Instead,
it is your responsibility to dispose of the waste electrical and electronic parts of this product by handing them over to a company or organisation
authorised for the recycling of waste electrical and electronic equipment. For more information about arrangements for waste equipment disposal
please contact your Knorr-Bremse distributor or local Knorr-Bremse representative.

8
» Y364866 – (EN - REV. 000) | March 2020

9
1
» Service Manual - KB4TA-D
1 KB4TA-D System Overview
1.1 Function
Fig. 1 KB4TA-D Overview
The Basic Knorr-Bremse KB4TA-D brake system comprises a KB4TA-D ECU ES1220 plus
two ABS Modulator Valves. It is designed for air braked trailers with mechanical or air
suspension. KB4TA D is designed to work in trailer systems powered via ISO 7638 but
the addition of ISO 1185 stop lamp powering is included as standard as a safety feature
so, in the event that there is no ISO 7638 powering, the ABS function is maintained.
The KB4TA-D ECU is designed for all normal system variants from 2S/2M up to 4S/3M. The conguration as supplied is 2S/2M, but
with the integrated auto-conguration the ECU detects additional sensors and adjusts upward to 4S/2M automatically. Other con-
gurations and additional functions can be quickly and eectively achieved using PC Software ECUtalk®. For 4S/3M applications an
additional external (third) ABS is necessary The KB4TA-D brake system is capable of working with drum brake or disc brakes and the
systems shown below are only typical. For more systems see PD-203-580, Document No. Y250913.
Note:
Stop lamp powering should only be considered as a backup in the event of failure of
the ISO 7638 connection.

10
1
1
1-2
2
21
3
1
4
2
1
4
2
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
7
7
3
2
1
4
5
8
6
» Y364866 – (EN - REV. 000) | March 2020
KB4TA-D System Overview
BOM list for Fig. 2
No. Description Part No. Qty
1 TABS ECU K068353N00 1
2 TABS Relay Modulator Valve K019290TY 2
3 TABS Relay Modulator Valve Cable K159651N49 1
4 Power Supply Cable K159650N49 1
5 TABS 3m Extension Cable K159652N49 4
6 Park and Shunt Valve K015380N00 1
7 Palm Coupling Brake-Yellow K000954 1
8 Palm Coupling Supply-Red K000952 1
Fig. 3 System Diagram4S/2M Semi-trailer with mechanical (split system)
Legend:
1
ABS-Connector ISO 7638
2 Coupling Head with
Filter - “Control”
3 Coupling Head with
Filter - “Supply”
4 Park-/Shunt Valve with
Emergency Function
5 Trailer wheel
6 Air Reservoir
7 ABS Relay Modulator
Valve
8 ABS ECU
Example KB4TA System diagram (4S/2M) for semi-trailer with mechanical suspension in China (split system)

11
1
1
1-2
2
21
3
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
11
SERVICE
PARKING 12
1
4
2
1 4
2
3
2
1
4
5
7
6
» Service Manual - KB4TA-D
KB4TA-D System Overview
BOM list for Fig. 3
No. Description Part No. Qty
1 TABS ECU K068353N00 1
2 TABS Relay Modulator Valve K019290TY 2
3 TABS Relay Modulator Valve Cable K159651N49 1
4 Power Supply Cable K159650N49 1
5 TABS 3m Extension Cable K159652N49 4
6 Park and Shunt Valve K015380N00 1
7 Palm Coupling Brake-Yellow K000954 1
8 Palm Coupling Supply-Red K000952 1
Example KB4TA System diagram (4S/2M) for semi-trailer with mechanical suspension in China (integrate model)
Legend:
1
ABS-Connector ISO 7638
2 Coupling Head with
Filter - “Control”
3 Coupling Head with
Filter - “Supply”
4 Park-/Shunt Valve with
Emergency Function
5 Trailer wheel
6 Air Reservoir
7 ABS Integrate model
Fig. 3 System Diagram4S/2M Semi-trailer with mechanical (integrate model)
Note:
Alternative cables can be found in the section cables for the KB4TA-D

12
1
» Y364866 – (EN - REV. 000) | March 2020
KB4TA-D System Overview
1.2.1 Power up Sequence
1.2 System Description
1.2.2 Trailer ABS Warning Lamp (No Active Fault)
1.2.3 Trailer ABS Warning Lamp (With Active Faults)
1.2.4 Modulator‘Chu Test’ at Power up
At power up, the KB4TA D ECU performs a series of self-checks that can assist a technician to determine the ABS system status and
conguration.
At power up (when no active 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 o.
At power up (when active 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 active fault will displayed according to the blink code, diagnostic trouble code described in the
section “ Diagnostics”
At power up, the KB4TA-D ECU activates a modulator ‘chu test’. This electrical and pneumatic ABS modulator test can help the
technician identify problems with modulator installations and/or wiring.
When power supplied, a properly installed modulator will generate ve rapid audible ‘chus’of air pressure on the left internal
modulator followed by ve ‘chus’on the right modulator. There will then be ve further ‘chus’on the additional axle modulator if
tted .
If the ECU is wired incorrectly, the modulator will only produce one ‘chu’, or no ‘chus’at all. If a fault is detected during the modu-
lator ‘chu test’, compare the wiring and piping to the electrical system schematic and make any necessary alterations.
BOM list for TABS Kit
No. Description Part No. Qty
1 TABS Kit K188808 1
3 TABS Relay Modulator Valve Cable K159651N49 1
4 Power Supply Cable K159650N49 1
5 TABS 3m Extension Cable K159652N49 4
6 Park and Shunt Valve K015380N00 1
7 Palm Coupling Brake-Yellow K000954 1
8 Palm Coupling Supply-Red K000952 1
9 Valve connection cable K191808 1
10 Nuts C31865 9
11 Bolts K194144 9

13
1
» Service Manual - KB4TA-D
KB4TA-D System Overview
1.2.6 Normal Braking
1.2.7 Odometer Function
1.2.5 ABS Operation
During normal braking, the KB4TA D ECU system operates as two standard relay valves in parallel. If the ECU does not detect exces-
sive wheel slip, ABS control will remain inactive while the vehicle is braked according to driver demand.
Odometer
The KB4TA D ECU has an odometer function to provide a means of storing the accumulated mileage of the trailer. The mileage is
computed by utilizing information calculated from the wheel speed sensors. This feature will accurately store mileage information
up to 1,000,000 km. The accuracy of readings higher than this cannot be guaranteed. The mileage can be displayed using PC diag-
nostics ECUtalk® or through blink codes.
Trip Counter
The KB4TA-D ECU provides a counter to record the trip mileage. The feature is accessed through PC diagnostics ECUtalk®.
Non Standard Tyre Sizes
The KB4TA D ECU allows for tyre rolling radius and sensing ring tooth count parameters to be set for each axle using a diagnostic
tool ECUtalk®. This setting is necessary for the ECU to accurately calculate the vehicle speed and determine the odometer mileage.
Wheels of the same axle must be set to the same rolling radius and sensing ring tooth count. In most cases, these parameters are
set by the trailer OEM and do not need to be adjusted. In the case of a service replacement unit, always check that these param-
eters are set to match the vehicle. Refer to the manufacturer’s tyre specication for correct values. Sensing ring tooth count is
defaulted to 100 teeth, but can be adjusted between 60 and 120 teeth.
KB4TA-D provides basic service braking in addition to the ABS function. The KB4TA D ECU is used to prevent the wheels of a trailer
locking whilst braking. The friction between the tyre and the road is created by relative movement between their two surfaces, i.e.
dierence in surface speeds of road and tyre and is referred to as‚slip‘. It is well known that a wheel operating on a wet surface has
reduced friction (adhesion) and hence can transmit reduced braking eort to the road.
The KB4TA-D ECU constantly monitors the rotational speed of all sensed wheels on the trailer by using the wheel speed sensor
outputs. It then calculates an average of these wheel speeds (Reference Speed) and constantly compares it with the speed of each
wheel.
During braking, if one or more wheels is on a slippery surface and is unable to support the level of braking that it is being asked to
contribute, the wheel speed will drop relative to the Reference Speed, i.e. there will be ‘slip’, and deceleration of that wheel will in-
crease. The KB4TA-D ECU will normally detect this during the application of the brake and, before the wheel becomes locked, send
an electrical signal to the appropriate modulator to reduce the pressure in the service brake actuator(s) on that wheel or group of
wheels. Once the wheel starts to accelerate and the slip is reduced, the KB4TA-D ECU will send an electrical signal to the modulator
to gradually increase the pressure until either the wheel again starts decelerating or the requested level of braking is reached. It is
therefore possible to maximise the utilisation of the available adhesion to improve stopping distance whilst maintaining stability.

14
1
» Y364866 – (EN - REV. 000) | March 2020
KB4TA-D System Overview
1.2.10 ABS Manual Conguration
1.2.11 Auxiliary Conguration
1.2.12 Auxiliary Conguration
Depending upon the required ABS conguration it may be necessary to use the diagnostic tool ECUtalk® to manually congure the
KB4TA D ECU, i.e. 4S/3M ABS conguration.
Once manually congured, the KB4TA D ECU will no longer auto-congure, unless the “Reset ABS Conguration” option is used in
the diagnostic tool ECUtalk®.
The KB4TA D ECU supports the conguration of auxiliary functions on AUXIO1 and AUXIO2 using the diagnostic tool ECUtalk®.
However, the associated pins can only be congured as AUXIO if they are not already congured as 4S/3M and stop lamp power
respectively.
ADL is a programming language, developed and patented by Knorr-Bremse, that enables the expansion of the functionality of the
TEBS Brake Module without having to update the basic hard coded software; this enables signicant exibility. By using an ADL
program it is possible to adapt the individual or combined functionality of any combination of congured AUXIO functions as well
as update the content of the J1939 CAN communications to realise specic customer objectives.
ADL is an important feature for the following reasons:
• Continuous development within the commercial vehicle industry in general and a varied customer base demands
exibility.
• A clear trend towards realising an increasing number of functions by electronic means.
• Products are developed based on what is known to be required up to the time of launch. The introduction of new
functions takes signicant time to introduce on a permanent basis.
• Special applications require special solutions.
1.2.8 Service Interval
1.2.9 ABS Auto Conguration
The KB4TA D ECU provides a feature that can be used to indicate a service interval for the trailer. The service interval can be ac-
cessed via PC diagnostics ECUtalk®. If congured, the KB4TA D ECU can ash the warning lamp when the vehicle is at standstill and
the ABS is rst powered to indicate when the service interval has been exceeded. Conguration of the KB4TA D ECU
When manufactured the KB4TA D ECU has a default ABS conguration of 2S/2M. If the ABS conguration has not been manually
set using the diagnostic tool ECUtalk® then, at power up, if the KB4TA D detects additional sensors it will perform an auto-cong-
uration. An auto-conguration only adjusts upward (e.g. from 2S/2M to 4S/2M). A conguration will not be accepted if a wheel
speed signal is generated at the time of conguration.
A 4S/3M conguration cannot be realised automatically, this requires manual conguration with the diagnostic tool ECUtalk®.

15
2
» Service Manual - KB4TA-D
2.1.1 ECU Errors
2.1.2 Low and High Voltage Operation
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 ECUtalk®. 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 ECUtalk®.
Depending on the detected error and the ABS conguration the ECU will either partially or totally disable the ABS function as
follows:
• 2S/2M congurations: total shut down.
• 4S/2M congurations: Reduce to 2S/2M
• 4S/3M congurations: Reduce to 2S/2M.
The above shutdown modes are dependent on the type and location of the detected error. For more information see ABS Elec-
tronics 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 rectied at the earliest opportunity.
The KB4TA D ECU supports the conguration of auxiliary functions on AUXIO1 and AUXIO2 using the diagnostic tool ECUtalk®.
However, the associated pins can only be congured as AUXIO if they are not already congured as 4S/3M and stop lamp power
respectively.
Should the supply voltage to the ECU be outside the dened voltage range (18 to 32V) the ABS function is disabled while normal
brake control remains available.
2 ERROR DETECTION
2.1 ABS Shutdown

16
3
» Y364866 – (EN - REV. 000) | March 2020
3 KB4TA-D ABS ECU
3.1 Function
Fig. 4 ECU for the KB4TA-D
Note:
Stop lamp powering should only be considered as a backup in the event of
failure of the ISO 7638
The KB4TA D ECU is designed for all normal system variants from 2S/2M up to 4S/3M. The conguration as supplied is 2S/2M for use
with two external ABS modulators (see PD 203-360, Document No. Y250908), but with the integrated auto-conguration the mod-
ule detects additional sensors and adjusts upward to 4S/2M automatically. Other congurations and additional functions can be
quickly and eectively achieved using PC Software ECUtalk®. For 4S/3M applications an additional external (third) ABS modulator is
necessary (see PD 203-360, Document No. Y250908).
Depending on the version, the KB4TA D ECU has the option of various auxiliary functions:
• Odometer/trip counter/service interval
• Reset to Ride (RtR)
• Integrated Speed Switch (ISS)
• ABS Active
• Brake wear monitoring
• Stop lamp powering
• Headboard warning lamp
• 24V output
To ensure fast and eective trouble shooting, the KB4TA D ECU can be used with a universal diagnostic interface which, with
diagnostic software ECUtalk®, allows connection to a personal computer (PC) for fault diagnosis, odometer reading and velocity
output parameter setting. Alternatively, a diagnostic blink code can be displayed on the towing vehicle’s “in-cab”and/or the trailer
headboard warning light. This can be activated via the stop lamp supply by depressing the foot brake valve in the towing vehicle.
For more information see PD-403-390, Document No. Y250910.
The KB4TA D ECU with external ABS modulators is designed to be used as the service replacement part for the Knorr-Bremse
KB3TA, A9 & A18 trailer ABS modules.
Technical Data:
• Operating temperature range: -40 °C to +65 °C
• Weight: 1.2 kg approximately
• Degree of protection: DIN 40050 part 9 IP69K
• Nominal Voltage: 24 V DC
The Knorr-Bremse KB4TA D ECU ES1220 is designed for air braked trailers
(semi-trailers, centre-axle trailers and full trailers) with mechanical or air suspen-
sion.
KB4TA D is powered via ISO 7638. As an additional safety feature the ISO 1185
connection is included as standard so, in the event that there is no ISO 7638
powering, the ABS function is maintained.

17
3
X2
4
» Service Manual - KB4TA-D
KB4TA-D ABS ECU
3.2 Electrical Connections
Fig. 5 Electrical Connection for ECU K068353
X1 - Code A
X1 Connector
X2 Connector
SR − Right Sensor
SAR − Additional Right Sensor for 4S/2M and
4S/3M
ISO 7638 Connection (5 Pins) X1-4 = ISO 7638 Pin 4 valve ground
X1-6 = ISO 7638 Pin 1 valve supply X1-7 = ISO 7638 Pin 3 ignition / warning lamp ground
X1-8 = ISO 7638 Pin 5 warning lamp X1-9 = ISO 7638 Pin 2 ignition
SL − Left Sensor
SAR − Additional RLeft Sensor for 4S/2M and
4S/3M
X1 - Code B
The Knorr-Bremse KB4TA D ECU connectors use a 12-pin Deutsch DT series connector (Code A) for ISO 7638 power supply, diag-
nostics and auxiliary I/Os such as ISO 1185 stop lamp power supply, additional third modulator and one additional Input/Output.
Also a Code B connector for the connections to the ABS Relay Modulators.
The ECU also utilizes either two or four wheel speed sensor inputs:
• SL & SR are used for 2S/2M applications.
• SAL and SAR are additional connections for 4S/2M and 4S/3M applications, note: these sensors may be installed on
lift axles in certain system applications.
3.2.1 ECUs K068353
Pin Signal Connection
X1-1 AUXIO10 Auxiliary Input/Output
(4S/3M: Valve 3rd Modulator)
X1-2 AUXRET23 Return Line for AUXI03
(Diagnostics Ground)
X1-3 TI_CANL 5V-CAN Low for Diagnostics
X1-4 GND_M System Ground
(ISO 7638 - ABS connector - Pin 4)
X1-5 TI_CANH 5V-CAN High for Diagnostics
X1-6 BAT Valve Supply Voltage
(ISO 7638 - ABS connector - Pin 1)
Pin Signal Connection
X2-3 MV1 (SL side) 24V Modulator 1 (pin 6.3)
X2-4
MV2 (SR side) 24V Modulator 2 (pin 6.3)
Pin Signal Connection
X2-9 LSS1 GND Modulator 2 (pin 6.2)
X2-10
LSS1 GND Modulator 1 (pin 6.2)
Pin Signal Connection
X1-7 GND_H System Ground
(ISO 7638-ABS connector-Pin3)
X1-8 WL Warning Lamp Ground
(ISO 7638 - ABS connector - Pin 5)
X1-9 IGN ECU Supply Voltage
(ISO 7638 - ABS connector - Pin 2)
X1-10 AUXIO3 (DIA)
Auxiliary Input/Output
(Diagnostics Supply Voltage)
X1-11 AUXIO2/
GND_BL
Auxiliary Input/Output
(Stop lamp ground)
X1-12 AUXRET1/BL
Return Line for AUXI01 (Stop lamp Supply)
(4S/3M: Return Line 3rd Modulator)

18
3
1
4
» Y364866 – (EN - REV. 000) | March 2020
KB4TA-D ABS ECU
Diagnostic Connector
KB4TA D harnesses provide a 4-pin 5 Volt J1939 CAN diagnostic connection for a diagnostic tool. Remote diagnostic cables are
available from Knorr-Bremse to provide a J1939 diagnostic port at the side of the trailer.
X1-2 = Diagnostics ground
X1-3 = 5 Volt CAN low
X1-5 = 5 Volt CAN high
X1-10 = 24 Volt diagnostics supply
12 11 10 9 8 7
ISO 1185
X1 - Grey Connector
Fig. 6 Installation: Stop Lamp Power with External Warning Lamp
Pin Connection
1 Common return
2 Left-hand rear position, end outline marker light and rear registration plate illuminating
3 Left-hand direction-indicator light
4 Stop lamp
5 Right-hand direction-indicator light
6 Right-hand rear position, end outline marker light and rear registration plate illuminating
7 Connection “54g“ - free
Note:
The use of a headboard mounted warning lamp is prohibited on vehicles approved to ECE Regulation 13 unless national require-
ments specically allow the installation.
Note:
A system congured for stop lamp power can not support 4S/3M system conguration
3.2.2 Stop Lamp Power
The KB4TA D ECU provides a connection for stop lamp power, with an optional connection for a headboard mounted warning
light.

19
3
» Service Manual - KB4TA-D
KB4TA-D ABS ECU
Fig. 7 Fixing for the KB4TA-D ECU without Cover
Note:
Tightening torque of the M8 retaining nuts/screws = 24 +/- 4.8 Nm.
The ECU should be mounted on a at surface. The cable entries must not point upwards. The pressure compensation hole on the
back must not be blocked.
3.2.3 Stop Lamp Power
3.3 Installation
Diagram showing xings for the KB4TA D ECU (view without Cover)
KB4TA D oers two independent possibilities for diagnostics:
• Blink Code diagnostics (ABS warning lamp in the cab and/or headboard warning lamp). This function is integrated in
ECU.
• Direct access to the module via PC and software ECUtalk® (all relevant congurations and EOL are possible) For more
information section for the diagnostics

20
3
» Y364866 – (EN - REV. 000) | March 2020
KB4TA-D ABS ECU
3.4 Label Information
The small identication label (1) is located on the top of the ECU. A further label (2) containing additional information is located
under the removable cover of the KB4TA D ECU. If the part number label is not readable or is painted over, the ECU part number
and revision can be read using the PC diagnostic tool ECUtalk®. The ECU part number, and pin-out information is shown on the
label beneath the removable cover.
Fig. 8 Label Information
Module Production Date (Year, week, day, serial number
(EMC)
Electromagnetic
Compatibility number
1. Fit the KB4TA D ECU to the trailer either:
- on a cross member in the centre of the rear axle bogie or
- on the trailer headboard.
2. If required t the additional axle modulator, normally on a cross member in the centre of the front axle bogie.
3. Make the necessary pneumatic connections between the pneumatic components.
4. Make the necessary electrical connections - see PD-203-380, Document No. Y250909.
Required checks after installation
1. Before performing the checks, chock the wheels.
2. Fully charge air brake system and verify proper brake adjustment.
3. Make several trailer brake applications and check for prompt application and release at each wheel brake.
4. Check the module, modulator valve(s) and all air hose ttings for leakage using a soap solution.
5. Apply power and monitor the power-up sequence to verify proper system operation.
6. Determine the current ABS conguration by activating blink code diagnostics or using the PC diagnostic tool ECUtalk®
(see PD-203-390, Document No. Y250910).
7. Where necessary congure the required ABS conguration and Auxiliary conguration using the diagnostic tool ECUtalk®.
8. It is recommended that a full EOL check is carried out using the diagnostic tool ECUtalk®.