Operation and Maintenance Manual forWP10 Series Four-valve Diesel Engine (China IV, V)
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(2) Inspection and maintenance on critical components (such as injection pump, ECU, common rail and
turbocharger) shall be performed by Weichai designated service stations.
6.2Common Faults and Troubleshooting
6.2.1Failure in diesel engine starting
(1) The starter motor does not work
The starter motor of WP10 series China IV/V diesel engines are controlled by ECU. Under normal working
conditions, the ECU produces anoutput current to drive the starter relay. When the relay is activated, the battery
drives the starter motor to start the engine. In case of start failure, you should mainly check the neutral gear.
Factors to be checked: correlation between neutral gear switch, starter relay, battery and off-vehicle shutdown
switch and related parts.
◆ Check whether the gear shift is at neutral position.
Before starting, check whether the gear shift is at neutral gear position.
◆ Check the position of off-vehicle shutdown switch (which should be at OFF position).
The off-vehicle shutdown switch is of inching switch and capable of automatic reset. Check this switch for normal
functioning.
If the switch cannot reset automatically, check whether it is at ON position.
◆ Check the neutral switch and its wiring to ensure they are under sound conditions, and try to perform
emergency starting (press down and hold the ignition switch for more than 5s).
For the engine of which the starter motor is controlled with ECU, when starting, the ECU determines whether the
gear shift is placed at neutral position based on the signal from the neutral switch. When the neutral switch or its
wiring is damaged, no neutral position signal will be received by ECU, and the starter motor will not work.
◆ Check whether the battery voltage is too low to drive the starter motor.
Normally, the battery voltage is 24V. If the voltage is too low, the starter motor cannot be driven to work. Actual
“battery voltage” can be measured with voltage range of the or with the fault diagnostic device.
◆ Check whether the starter relay and its wiring are under sound conditions.
Check the surface of the wiring terminals for excessive oxide, and check the wiring terminal bolt for looseness or
fracture.
◆ Check whether the starter motor has been burnt.
Check with whether the starter relay is functioning properly.
◆ Check whether the ignition switch and starting switch are damaged.
Turn the ignition key to “ON” position, and check whether the panel lamp becomes on;
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