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Doc. No. Y250910 (EN - Rev. 001)
September 2016
KB4TA / KB4TA D System Diagnostics
P r o d u c t D a t a
PD-203-390
Chart 1
Power-up Sequence − Dashboard mounted ABS Warning Lamp
NO
NO
YES
Dashboard-mounted Trailer
ABS Warning Lamp at Power up.
Trailer ABS warning lamp does not come
on at power up.
Troubleshoot the lamp circuit on the
towing vehicle.
Verify that the trailer is connected to the
towing vehicle via the 5-pin ISO 7638
connector. Turn ignition on and observe
the dashboard-mounted trailer
ABS warning lamp.
Verify that the dashboard-mounted ABS
warning lamp stays “ON”
for approximately 2 seconds and then
turns “OFF”.
The KB4TA module/KB4TA D ECU is
functioning normally. No service to the
ABS components is needed.
Verify that the dashboard-mounted trailer
ABS warning lamp illuminates within
2 seconds of ignition power being
applied to the vehicle.
The dashboard-mounted trailer ABS warning lamp stays
“ON”. This is an indication that the trailer ABS system has
a fault.
Go to Quick Reference table.
If the dashboard-mounted trailer ABS warning lamp
remains “ON” with no trailer connected,
troubleshoot the lamp circuit on the towing vehicle.
If the trailer ABS lamp remains “ON” with a trailer
connected, rerun the power-up sequence for trailer-
mounted ABS warning lamp.
Go to Quick Reference table.
Does the warning lamp go out when driven at a
speed >7km/h. => no error (stored dynamic wheel
speed sensor error).
YES
YES
NO
Diagnostic Troubleshooting Flow Charts
Diagnostic trouble code information can be retrieved from the KB4TA module/KB4TA D ECU by using blink code
diagnostics or the PC diagnostic tool ECU
talk
®. The following troubleshooting flow charts will help the technician
isolate the cause of the problem and confirm whether the problem lies in the component, wiring or connectors.
Troubleshooting should always begin by observing the dashboard or trailer-mounted ABS warning lamp
during the KB4TA module/KB4TA D ECU’s power-up sequence.
If it is necessary to make electrical measurements, always begin by taking voltage and resistance measurements at
the 12-pin ECU harness connector.
Once the circuit problem is found, isolate the area needing attention by repeating the measurements at all connections
in the affected circuit working towards the modulator, wheel speed sensor, etc.
No voltage or resistance measurements must to be made on the X1 connector pins of the KB4TA module/
KB4TA D ECU.
The following pages contain detailed information.
Y026787: 006: EN: Released: Fri Nov 11 11:18:50 CET 2016:
