Testing Of Ecu Inputs + Outputs - jcb JS300 Service Manual

Care should be taken when testing the inputs + outputs of
the ECU to ensure that correct test method is used to
determine if the ECU is functioning normally.
Testing Low Side Input
With the switch open the meter will read 0v.
With the switch closed the meter will read 24-28v.
ECU
Input
Fig 16.
Testing High Side Input
With the switch open the meter will read 0v.
With the switch closed the meter will read 24-28v.
ECU
Input
Fig 17.
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Testing of ECU Inputs + Outputs

Switch (rocker, momentary,
pressure, level, etc.)
Red lead
V
Black lead
C005840GB
Switch (lights, engine preheat,
etc.)
Red lead
V
Black lead
C005850GB
Testing Low Side Output
With the output off the meter will read 0v.
With the output on the meter will read 24-28v.
ECU
Output
Testing High Side Output
With the output off the meter will read 0v.
With the output on the meter will read 24-28v.
ECU
Output
The ECU is internally configured to give short circuit
protection and detection of short circuit / open circuit, this
is done by internal resistors. This internal configuration can
give some confusing results when testing the outputs on
the ECU.
Voltage at point A:
9813/5100-1
Section C - Electrics
Electronic Controllers
Testing of ECU Inputs + Outputs
Actuator; relay coils
Red lead
V
Black lead
Fig 18.
Actuator (solenoid, motor,
bulb, horn relay)
Red lead
V
Black lead
Fig 19.
+24
C005860GB
C005870GB
C-57