Code [731/Ca731] Eng. Bkup Speed Sensor Phase Error - Komatsu 114E-3 Series Shop Manual

SEN00460-01
E-45 Code [731/CA731] Eng. Bkup Speed Sensor Phase Error
Error code Failure code
731
Contents of
• Abnormal phase is detected in signals of engine Ne speed sensor and engine Bkup speed sensor.
trouble
Action of
• Controls with signals of engine Ne speed sensor.
controller
Problem that • Engine does not start or is difficult to start.
appears • Idle speed is unstable.
on machine • Exhaust smoke is black.
Related infor-
• Method of reproducing failure code: Start engine.
mation
Broken engine Ne speed
1
sensor
Broken engine Bkup speed
2
sensor
Defective or broken mount of
3 rotation sensing ring on
crankshaft side
Possible
causes and
standard value
Defective or broken mount of
in normal state
4 rotation sensing ring on cam-
shaft side
Defective timing between
5
crankshaft and camshaft
Defective connection of
6
ground terminal
34
Trouble
CA731
Causes
Abnormality in engine Bkup speed sensor phase
Standard value in normal state/Remarks on troubleshooting
Inspect engine Ne speed sensor for breakage directly.
Inspect engine Bkup speed sensor for breakage directly.
Inspect it for defect or breakage according to the following proce-
dure.
1) Set No. 1 cylinder to compression top dead center (align stamp-
ing mark).
2) If center of speed sensor ring notch is at end of Ne speed sensor,
speed sensor ring is installed normally.
Inspect rotation sensing gear for defect or breakage according to
the following procedure.
1) Set No. 1 cylinder to compression top dead center (align stamp-
ing mark).
2) Remove Bkup speed sensor.
3) If groove of rotation sensing gear side can be seen through sen-
sor mounting hole, it is mounted normally.
Inspect crankshaft and camshaft for timing directly.
Inspect following directly for connection of ground terminal.
• Ground terminal (battery (–)) of machine main unit.
• Ground terminal of engine
• Ground terminal of engine controller
• Ground terminal of starting motor
40 Troubleshooting
1
114E-3 Series