Knorr-Bremse Group
9
Doc. No. Y250910 (EN - Rev. 001)
September 2016
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KB4TA / KB4TA D System Diagnostics
C o m m e r c i a l V e h i c l e S y s t e m s
PD-203-390
Chart 4
Troubleshooting the ISO 7638 (and ISO 1185 if connected) Power Supply
NO
YES
KB4TA/KB4TA D Module Wiring Harness,
ECU X1 Connector - measure:
Pin 9 (Ignition Power) to Pin 7 (ground)
12 11 10
9
8
7
KB4TA/KB4TA D Module Wiring Harness,
ECU X1 Connector - measure:
Pin 12 (Stop lamp Power) to Pin 11 (ground)
12 11 10
9
8
7
KB4TA/KB4TA D Module Wiring Harness,
ECU X1 Connector - measure:
Pin 6 (Battery Power) to Pin 4 (ground)
12 11 10
9
8
7
Turn off power to module,
disconnect the 12-pin-connector.
With ignition power, battery power &
stop lamp power to the trailer.
Measure voltage between the ignition
pin and its corresponding ground,
measure voltage between the battery
pin and its corresponding ground,
measure voltage between the stop
lamp supply and stop lamp ground.
The operating range should be bet-
ween 18 and 32 Volts DC.
With a voltmeter, check power and
ground wires. Look for corroded or
damaged wires or pins.
If corrections are made, rerun the
power-up sequence.
With the voltmeter, check the power
and ground wires. Look for corroded
or damaged wires or pins.
If corrections are made, rerun the
power-up sequence.
Check for high resistance (corrosion,
wire/connector damage or improper
termination of the power line) resulting
in high voltage drop across the lines.
Measure the voltage under load by
placing a load such as a stop lamp bulb
with ignition power, battery power &
stop lamp power to the trailer.
Measure voltage between the ignition
pin and its corresponding ground,
measure voltage between the batte-
ry pin and its corresponding ground,
measure voltage between the stop lamp
supply and stop lamp ground.
The operating range should be
between 18 and 32 Volts DC.
Verify that the voltage drop measure-
ments are not more than 1 Volt DC at
each of the respective vehicle circuits
(ignition, battery and stop lamp).
Y026787: 006: EN: Released: Fri Nov 11 11:18:50 CET 2016:
