JLG 20VP (3120728) Service Manual - Manual (Page 91)

SECTION 3 - TROUBLESHOOTING
3120728 – JLG Lift – 3-31
Table 3-21. Pump Circuit
• Battery voltage 24 volts. (Fully charge batteries)
• Key switch set to Platform .
STEP ACTION SPEC YES NO
1. At the pump motor, check for 24 volts at both ends of the battery
cable running from the main contactor to the pump case stud. (left
side)
24 volts Go to Step 2
Tighten
Connection or
Replace Cable
if Necessary
PUMP CONTACTOR RELAY CIRCUIT
2. Check the connection of the ground cable (attached to 5/16" stud,
left side) to the pump contactor, is tight and connected on other end
to B- at the right side battery.
Ground Go to Step 3
Tighten
Connection or
Replace Cable
if Necessary
3. Check the connection of the ground cable (other side) is tight and
connected to the pump case stud (center).
Ground Go to Step 4
Tighten
Connection or
Replace Cable
if Necessary
4. Check the Yel/Red, 2-6 wire connected to the positive post on the
pump case for tightness and 24 volt reading.
24 volts Go to Step 5
Tighten/Repair
Connection
5. Check the Tan, 55-1 wire connected to both the Ground control
switch and the MC-1 box, X105 connector, pin 5 through the pump
contactor relay. Without any lift functions activated, it should show
24 volts, with a lift function activated it should show ground.
Ground Go to Step 6
Tighten/Repair
Connection
DUMP VALVE CIRCUIT
6. Check the Yel/Red, 2-6 wire connected to the positive (+) post on
the pump case for 24 volts.
24 volts Go to Step 7
Tighten/Repair
Connection
7. Check the Tan, 3-1 wire connected to both the Ground control
switch and the MC-1 box, X105 connector, pin 4 through the lift up
valve. Without any lift function activated, it should show 24 volts,
with a lift function activated it should show ground.
24 volts Go to Step 8
Tighten/Repair
Connection
DOWN VALVE CIRCUIT
8. Check the Yel/Red, 2-6 wire connected to the positive (+) post on
the pump case for 24 volts.
24 volts Go to Step 9
Tighten/Repair
Connection
9. Check the Tan, 4-1 wire connected to both the Ground control
switch and the MC-1 box, X105 connector, pin 6 through the lift
down valve. Without any lift functions, it should show 24 volts, with
a lift function it should show ground.
24 volts Go to Step 10
Tighten/Repair
Connection
MAIN CONTACTOR CIRCUIT
10. Check the battery cable from the B+ (left side) battery for 24 volts.
24 volts Go to Step 11
Tighten/Repair
Connection
11. Check the battery cable going out to the pump case (left side) stud
for 24 volts.
24 volts Go to Step 12
Tighten/Repair
Connection
12. Check the Yel/Red, 2-5 (10 ga.) wire to the MC-1 box, X101 connec-
tor, pin A1 for 24 volts.
24 volts Go to Step 13
Tighten/Repair
Connection
13. Check the Yel/Red, 2-4 wire to the Power Relay, pin #87 for 24
volts.
24 volts Go to Step 14
Tighten/Repair
Connection