Kubota KX91-3a User Manual

II-160
WSM Minor Change II Service Engineering Section
3) If the key switch fails to return and the engine speed sensor is also in trouble
If the key switch start signal is detected to have been on for 30 seconds, the automatic release con-
trol system (3) lets the transistor's base current flow, which turns on the release relay solenoid (1)
and turns off the relay switch.
2. Trouble shooting
1) Check if the safety lock lever is lifted.
Make sure that the safety switch is turned OFF.
Take the following steps, set the unit to tester mode, and check the condition of the safety switch.
A manual check with a circuit tester is possible.
2) Check if the prevention of start mode reentry is working. (Wait two seconds or more.)
3) Check if the auto release relay is turned OFF.
Make a manual check with a circuit tester.
4) Check if the wrong model settings are made.
Depending on the model, the start of the engine is judged at 1,000 rpm or below for KX41-3. There-
fore, the release of the starter motor is judged before the startup revolution of the engine is reached.
5) The reason why detecting engine speed is set at 1000 rpm ;
If 800 rpm is set to detect the engine start - up speed, the controller stops supplying the current to the
startor motor.
Under the low ambient temperature, engine may not start up at around 800 rpm.
Therefor, in order to make sure the actual engine start, sensing engine speed is set higher by 200
rpm.
This varies according to the models. Other than KX41-3, the stant of the engine is detected at 800
rpm.
a:Key switch status b:Engine speed sensor status c:Release relay solenoid action
(1) Normal:
No particular action
Normal Normal:
No particular action
(2) Start position
o Failure to return
Normal Relay deactivated 0.5 or 6 seconds
according the engine speed.
(3) Start position
o Failure to return
Engine failure to start, or no engine
speed sensor signal
Relay deactivated 30 seconds after
the key switch turn to "START"
a.Key switch start signal
b.Engine speed sensor signal
c.Release relay solenoid
Switch
turned off
30 sec
If Engine Does Not Start
Lever travel startKX91-3
(Service mode)
English Diagnosis Tester

Kubota KX91-3a Specifications

General

Brand	Kubota
Model	KX91-3a
Category	Excavators
Language	English