Service Manual Owner's manual

SECTION 3 - TROUBLESHOOTING
3-14 – JLG Lift – 3120728
No Power At Platform Control
Overview Of Procedure
The following procedure checks voltage and ground starting from the power source (batteries) through the ground control
station (key switch/E-stop) to the MC-1 box and finally to the platform control.
Check For These Obvious Conditions First:
• Battery voltage 24 volts. (Fully charge batteries)
• Keyswitch is turned to PLAT. (Platform)
• Both Emergency Stop Switches Reset (Ground/Platform). (Out)
• Connection of X102 Cable from MC-1 box to Platform Control, secure on both ends.
Table 3-5. No Power At Platform Control.
STEP ACTION SPEC YES NO
1. Check if the inline 5 amp fuse is blown on the Red, 1-1 wire at the
ground control station. (Ground control cover must be removed)
— If OK, go to Step 2 Replace Fuse
2. Check voltage to the Yel/Red, 2-2 wire at the MC-1 box, X101 con-
nector, pin 3.
24 volts Go to Step 3
Perform the E-
Stop/Key Switch
Circuit Check
(Table 3-17)
3. Check for Ground to the Black wire at the MC-1 box, X101 connec-
tor, pin A2.
Ground Go to Step 4
Check connec-
tion/wiring
between Battery
and X101, Pin A2
4. Check voltage to the Yel/Red, 2-3 wire at the MC-1 box, X101 con-
nector, pin 5.
24 volts Go to Step 5
Replace MC-1
Control Box
5. Check voltage to the Yel/Red, 2-5 wire at the MC-1 box, X101 con-
nector, pin A1.
24 volts Go to Step 13 Go to Step 6
6. Check voltage to the Yel/Red, 2-2 wire at the MC-1 box, X101 con-
nector, pin 3, from the Power Relay pin 30.
24 volts Go to Step7
Check the wire
between the
Power Relay and
Connection
7. Check voltage to the Power Relay, pin 87. 24 volts Go to Step 9 Go to Step 8
8. Check for Ground to the Power Relay on the Black wire pin 85, to
Ground.
Ground Replace Relay
Check wiring to
Ground
Connection
9. Check voltage to the Yel/Red, 2-4 wire at the Main Contactor from
the Power Relay, pin 87.
24 volts Go to Step 10
Check the Yel/
Red, 2-4 Wiring
10. Check for Ground, on the Black wire to the Main Contactor.
Ground Go to Step 11
Check wiring to
Ground
Connection
11. Check voltage at the Battery Cable from Battery to Main Contactor.
24 volts Go to Step 12
Check Battery
Cable
12. Check voltage to the Yel/Red, 2-5 wire at the Main Contactor.
24 volts
Check Yel/Red 2-
5 Wire
Replace Main
Contactor