No Boom Extend Or Retract - Skyjack SJ85 AJ Service Manual

Hydraulic System

4.3-5 No Boom Extend or Retract

No Boom Extend:
1. Stuck or defective differential sensing valve
DSV2.
2. Stuck or defective boom extend valve 4H-39.
3. Stuck or defective valve V2 (stuck open, or leak
to tank port).
4. Stuck or defective releif valve RV6 (stuck open, or
leak to tank port).
5. Stuck or defective counterbalance valve CB5.
6. Return valve V5 stuck in the closed position or is
defective.
7. Defective lift cylinder C2.
No Boom Retract:
1. Stuck or defective differential sensing valve
DSV2.
2. Stuck or defective boom retract valve 4H-38.
3. Stuck or defective valve V5 (stuck open, or leak
to tank port).
4. Stuck or defective counterbalance valve CB4.
5. Return valve V2 stuck in the closed position or is
defective.
6. Defective lift cylinder C2.
SJ85 AJ
Section 4 – Troubleshooting Information
Clean valve. Check O-rings on valve. Check
operation of valve. Repair or replace valve as
required.
Clean valve. Check operation of valve. Repair or
replace valve as required.
Clean valve. Check O-rings on valve. Check
operation of valve. Repair or replace valve as
required.
Clean valve. Check O-rings on valve. Check
operation of valve. Repair or replace valve as
required.
Clean valve. Check O-rings on valve. Repair or
replace valve as required.
Clean valve. Check operation of valve. Repair or
replace valve as required.
Check seals on cylinder. Replace as necessary.
Replace cylinder if defective.
Clean valve. Check O-rings on valve. Check
operation of valve. Repair or replace valve as
required.
Clean valve. Check operation of valve. Repair or
replace valve as required.
Clean valve. Check O-rings on valve. Check
operation of valve. Repair or replace valve as
required.
Clean valve. Check O-rings on valve. Repair or
replace valve as required.
Clean valve. Check operation of valve. Repair or
replace valve as required.
Check seals on cylinder. Replace as necessary.
Replace cylinder if defective.
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