Komatsu PC200-8M0, Shop Manual, Page: 662 / 1254

302 Troubleshooting by failure code, Part 2
Failure code [CA731] Eng Bkup Speed Sens Phase Error
40-302
42
PC200, 200LC, 220, 220LC-8M0
SEN06134-00
Failure code [CA731] Eng Bkup Speed Sens Phase Error
Action
level
Failure code
Failure
Engine Bkup Speed Sensor Phase Error
(Engine controller system)
L01 CA731
Detail of failure
q
Phase error is detected between signals from engine Ne speed sensor and engine Bkup speed
sensor
Action of con-
troller
q
Continues to control engine by using signal from engine Ne speed sensor.
Problem on
machine
q
Engine does not start at all or does not start easily.
q
Idle speed is unstable.
q
Exhaust gas becomes black.
Related infor-
mation
q Method of reproducing failure code: Start engine.
Cause Procedure, measuring location, criteria and remarks
1
Breakage of engine Ne speed sen-
sor
Engine Ne speed sensor may be broken. Check it.
2
Breakage of engine Bkup speed
sensor
Engine Bkup speed sensor may be broken. Check it.
3
Defective installation or breakage
of speed sensing wheel on crank-
shaft side
Speed sensing wheel on crankshaft side may be installed defectively or bro-
ken. Check it according to following procedure.
1. Align paint mark (M1) on damper with Ne speed sensor top (M2).
a
Do not align with mark of No. 1 cylinder compression top dead center
(approimately 80 deg. before compression top dead center).
2. If center of oblong hole (WS) of speed sensing wheel aligns with Ne speed
sensor top (M2), installation is correct.
4
Defective installation or breakage
of speed sensing ring on camshaft
side
Speed sensing ring on camshaft may be installed defectively or broken. Check
it according to the following procedure.
1. Set No. 1 cylinder to compression TDC (align with mark).
2. Remove Bkup speed sensor.
3. If you can see double-slot part (with one crest) (B) on speed sensing ring
through sensor mounting hole (H), speed sensing ring is installed correctly.
5
Defective timing of crankshaft and
camshaft
Timing of crankshaft and camshaft may be defective. Check it.
6
Defective connection of ground
terminal
Connection of ground terminal may be defective. Check following terminals.
q
Ground terminal of machine ((-) terminal of battery)
q
Ground terminal of engine
q
Ground terminal of engine controller
q
Ground terminal of starting motor