Applicable Systems
PC200 Excavator
Symptoms
Transmission shifts harshly between 1st and 2nd; operator reports jerk.
Possible Causes
- Shift solenoid valve response slow due to worn spool or coil resistance drift.
- Transmission clutch fill pressure incorrect (modulator valve worn).
- Transmission control ECU software needs reflash for shift timing.
Troubleshooting Steps
- Step 1: Measure shift solenoid resistance and activation time.
Resistance 28–32 Ω; response < 50 ms at 24 V. - Step 2: Read clutch fill pressure via service port during 1→2 shift.
Fill pressure peaks at 1.2 MPa then modulates to 2.8 MPa smoothly. - Step 3: Check ECU software version against Komatsu technical bulletin.
Version matches latest bulletin or updated if older.
How to Reset
Replace solenoid or modulator valve; reflash ECU; recalibrate clutch fill times.
Common Replacement Parts
- Shift Solenoid 56B-15-17210: Shift Solenoid 56B-15-17210
- Modulator Valve 417-18-31110: Modulator Valve 417-18-31110
Frequently Asked Questions
- Q: Can harsh shifting damage driveline?
Yes, repeated shocks wear universal joints and axle splines.
- Q: How often update ECU software?
Apply service bulletins as released; check annually.
Source: Komatsu WA380-6 Transmission Manual
Category: Heavy Equipment