JLG 20VP (3120849) Service Manual - Manual (Page 85)

SECTION 3 - TROUBLESHOOTING
3120849 – JLG Lift – 3-29
Platform Will Not Lower Using Platform Control
Overview Of Procedure
This procedure tests for ground coming out of the MC-1 box to the dump valve circuit and through to the ground control tog-
gle switch.
Check For These Obvious Conditions First:
• Battery voltage 24 volts. (Fully charge batteries)
• Hydraulic oil is within it’s specified operating temperature range.
Table 3-23. Platform Will Not Lower Using Platform Control.
STEP ACTION SPEC YES NO
1. Will machine lower manually, using the manual descent knob? — Go to Step 2 See (Table 3-26)
2. Will machine lower from ground control switch?
Note: Key switch must be set to GRND to check this.
— Go to Step 3 See (Table 3-23)
3. Check for ground on the Tan, 4-1 wire at the MC-1 box, X105 con-
nector, pin 6.
— Go to Step 4
Repair/Replace
Joystick/
MC-1 Box
4. Check for ground on the Tan, 4-1 wire at the lift down coil.
— Go to Step 5
Replace/Repair
Wire or
Connection
5. Check complete pump motor circuit . (See Table 3-21) — — —