Komatsu PC88MR-10 Shop Manual page 757

No. Cause
Pump controller is
6
defective.
Defective machine
7
monitor
Circuit diagram related to pump controller power supply
PC88MR-10
Procedure, measuring location, criteria, and remarks
If no failure is found by above checks, pump controller is defective.
(Since this is an internal defect, troubleshooting cannot be performed.)
If no failure is found by above checks, machine monitor is defective.
(Since this is an internal defect, troubleshooting cannot be performed.)
40 Troubleshooting
Troubleshooting by failure code (Display of code)
40-269