Failure Code [Ca778] Eng Bkup Speed Sensor Error - Komatsu PC200-8M0 Shop Manual

SEN06134-00

Failure code [CA778] Eng Bkup Speed Sensor Error

Action
Failure code
level
L01 CA778
q
Detail of failure Singal from engine Bkup speed (cam) sensor is abnormal.
Action of con-
q
Continues to control engine by using signal from engine Ne speed sensor.
troller
q
Problem on Starting performance is poor.
machine q Engine output lowers.
q
Method of reproducing failure code: Start engine.
q
Since inside of speed sensor is not coil but Hall sensor and electronic circuit, speed sensor cannot
Related infor- be determined to be normal by measuring its resistance with multimeter.
q
mation Since speed sensor outputs 5 V pulse voltage during normal operation, it cannot be measured by
using multimeter.
q
Speed sensor scans rotating slot of speed sensing ring mounted on camshaft.
Cause
Defective wiring harness connec-
1
tor
Defective sensor power supply 2
2
system
Damage or incorrect (loose) instal-
3 lation of engine Bkup speed (CAM)
sensor
Defective power input to engine
4
Bkup speed sensor
Open circuit in wiring harness
5 (wire breakage or defective con-
tact of connector)
6 Short circuit in wiring harness
Ground fault in wiring harness
7
(contact with ground circuit)
Hot short circuit in wiring harness
8
(contact with 24 V circuit)
44
40-302
Engine Bkup Speed Sensor Error
Failure
(Engine controller system)
Procedure, measuring location, criteria and remarks
See descriptions of wiring harness and connectors in "c: Electrical equipment"
in "Checks before troubleshooting" of "General information on troubleshoot-
ing", and check them.
If failure code [CA187] or [CA227] is also displayed, troubleshoot it first.
Engine Bkup speed (CAM) sensor may be damaged or incorrectly (loosely)
installed. Check it.
1. Turn starting switch to OFF position.
2. Disconnect connector CAM SENSOR , and connect T-adapter to female
side.
3. Turn starting switch to ON position.
Between CAM SENSOR (female) (1)
and (2)
1. Turn starting switch to OFF position.
2. Disconnect connectors ECM and CAM SENSOR, and connect T-adapters
to each female side.
Between ECM (female) (37) and CAM SENSOR
(female) (1)
Between ECM (female) (47) and CAM SENSOR
(female) (2)
Between ECM (female) (26) and CAM SENSOR
(female) (3)
1. Turn starting switch to OFF position.
2. Disconnect connectors ECM and CAM SENSOR, and connect T-adapters
to either female side.
Between ECM (female) (26) and (37) or CAM SEN-
SOR (female) (1) and (3)
Between ECM (female) (26) and (47) or CAM SEN-
SOR (female) (2) and (3)
1. Turn starting switch to OFF position.
2. Disconnect connectors ECM and CAM SENSOR, and connect T-adapters
to either female side.
Between ECM (female) (26) or CAM SENSOR
(female) (3) and ground
1. Turn starting switch to OFF position.
2. Disconnect connector CAM SENSOR, and connect T-adapter to female
side.
3. Turn starting switch to ON position.
Between CAM SENSOR (female) (3) and ground
302 Troubleshooting by failure code, Part 2

Failure code [CA778] Eng Bkup Speed Sensor Error

Power sup-
ply
PC200, 200LC, 220, 220LC-8M0
Voltage 4.75 to 5.25V
Resis-
Max. 10 z
tance
Resis-
Max. 10 z
tance
Resis-
Max. 10 z
tance
Resis-
Min. 100 kz
tance
Resis-
Min. 100 kz
tance
Resis-
Min. 100 kz
tance
Voltage Max. 1 V