Failure Code [Ca271] Pcv1 Short Circuit Error - Komatsu PC88MR-10 Shop Manual

Failure code [CA271] PCV1 Short Circuit Error

Action level Failure code
L03 CA271
Detail of
Short circuit is detected in supply pump control valve (SCV) circuit.
failure
Action of
controller
Problem on
Engine output lowers.
machine
Under normal conditions, pulse voltage of approx. 24 V is applied to SCV while engine is
Related
running. However, it cannot be measured by using multimeter since it is pulse voltage.
information
No. Cause
Defective wiring
1
harness connector
Defective supply pump
SCV
2
(internal short circuit)
Short circuit in wiring
3
harness
Ground fault in wiring
harness
4
(contact with ground
circuit)
Defective engine
5
controller
Circuit diagram related to SCV
PC88MR-10
PCV1 Short Circuit Error
Failure
(Engine controller system)
Procedure, measuring location, criteria, and remarks
1. See descriptions of wiring harness and connectors in "c: Electrical
equipment" in "Checks before troubleshooting" of "Related information on
troubleshooting", and check it.
2. Turn starting switch to ON position.
If this failure code is not displayed, wiring harness connector is defective.
a If this failure code is displayed, perform following checks.
1. Turn starting switch to OFF position.
2. Disconnect connector SCV and connect socket to male side.
3. Turn starting switch to ON position.
Resistance Between SCV (male) (1) and (2)
Resistance Between SCV (male) (2) and ground
1. Turn starting switch to OFF position.
2. Disconnect connector J1 and connect T-adapter to female side.
Between J1 (female) (30) and (40) (SCV
Resistance
resistance)
1. Turn starting switch to OFF position.
2. Disconnect connectors J1 and SCV, and connect T-adapter to female side
of connector J1.
Resistance Between J1 (female) (30) and ground
If no abnormality is found by above diagnosis, engine controller is defective.
(Since this is an internal defect, troubleshooting cannot be performed.)
40 Troubleshooting
Troubleshooting by failure code (Display of code)
(PC88MR-CA271-400-A-Z0-A)
1 to 5 z
Min. 1 Mz
1 to 5 z
Min. 1 Mz
40-155