Skyjack SJ20, Service Manual

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SJ20 238886ABA
Section 4 – Troubleshooting Information Hydraulic System
10. Loose or defective wiring from machine controller pins
WS, VS, and/or US to left traction motor
Check continuity. Replace if defective.
11. Loose or defective wiring from machine controller pins
WM, VM, and/or UM to right traction motor
Check continuity. Replace if defective.
12. Defective traction motor Check Motors. Replace if defective.
4.3 Hydraulic System
4.3-1 All Hydraulic Controls Inoperative (No Lift or Steer Functions)
1. Pump motor not engaged
Refer to Electrical troubleshooting. Replace pump
motor if defective.
2. Pump motor coupler defective Check coupler. Replace if defective
3. Defective pump P1 Check pump output. Replace if defective.
4. System relief valve RV1 set too low or stuck
open. Check and adjust valve setting. Replace if
defective.
4.3-2 No Lift Function
1. Check valve CV1 stuck closed
2. Stuck or defective lift valve 3H-14
4.3-3 No Lower Function
1. Stuck or defective lift valve 3H-14 Stuck or defective lift valve 3H-14
2. Stuck or defective lower valve 2H-13 Stuck or defective lower valve 2H-13
3. Blocked lower orifice OR1 Blocked lower orifice OR1
4.3-4 No Steer Left and/or Right
1. Stuck or defective steer valve 4H-23/4h-24
2. Steer crossover relief valve RV2 set too low or
stuck open. Check and adjust valve setting. Replace if
defective.
3.
Steer cylinder C5 bypassing, or mechanically binding
Check cylinder and all steer linkage. Repair or
replace defective componants as required.