Failure Code [Ca731] Engine Backup Speed Sensor Phase Error - Komatsu PC88MR-10 Shop Manual

Failure code [CA731] Engine Backup Speed Sensor Phase Error

CA731-400-A-Z0-A)
Action level Failure code
L01 CA731
Detail of Phase error occurs between signals of engine Ne speed sensor and engine Bkup speed
failure sensor.
Action of
Continues to control engine by using engine Ne speed sensor signal.
controller
Engine can not start or engine is hard to start.
Problem on
Idle speed is unstable.
machine
Exhaust gas color becomes black.
Related
Method of reproducing failure code: Start engine.
information
No. Cause
Damaged engine Ne
1
speed sensor
Damaged engine Bkup
2
speed sensor
Improper installation or
damage of speed
3
sensing wheel on
crankshaft side
Improper installation or
damage of speed
4
sensing ring on
camshaft side
Defective timing
adjustment of
5
crankshaft and
camshaft
Defective connection of
6
ground terminal
PC88MR-10
Engine Backup Speed Sensor Phase Error
Failure
(Engine controller system)
Procedure, measuring location, criteria, and remarks
Engine Ne speed sensor may be damaged. Check it.
Engine Bkup speed sensor may be damaged. Check it.
Wheel (W) on crankshaft side for speed sensing may be mounted incorrectly
or damaged. Check it by reading failure code [CA689].
Speed detection ring on camshaft side may be installed improperly or
damaged. Check it according to following procedure.
1. Rotate crankshaft clockwise when viewed from front to align wide notch
(a) of wheel for speed sensing (W) with "1.4 TOP" (b) on cover.
2. Remove Bkup speed sensor.
3. If you can see two slots on camshaft speed sensing ring (B) through
sensor mounting hole (H), ring for speed sensing is mounted correctly .
(Note that the two slots are visible only once in two turns, when #1 piston
comes to the top.)
Timings of crankshaft and camshaft may not be matched each other. Check
them.
Ground terminal may be poorly connected. Check following terminals:
Ground terminal of machine ((-) terminal of battery)
Ground terminal of engine
Ground terminal of engine controller
Ground terminal of starting motor
40 Troubleshooting
Troubleshooting by failure code (Display of code)
(PC88MR-
40-203