JLG 20VP (3120728) Service Manual - Manual (Page 82)

SECTION 3 - TROUBLESHOOTING
3-22 – JLG Lift – 3120728
Won’t Drive (Platform Elevated Only)
Overview Of Procedure
The following procedures check the components and circuits that feed data to the MC-1 Controller box assuring it is receiv-
ing the proper signals and conditions before engaging the machines’ drive motors.
Check For These Obvious Conditions First:
• Joystick Powered On
• Unit will Lift & Lower Platform
• Machine is not Tilted - (3 LEDs flashing at joystick control)
• PHP Device is not Obstructed - (4 LEDs flashing at joystick control)
• Brakes are not Released - (2 LEDs flashing at joystick control)
• Charger is not Plugged In - (8 LEDs flashing at joystick control)
Table 3-11. Won’t Drive with Platform Elevated
STEP ACTION SPEC YES NO
1. Check for ground on tilt circuit at MC-1 box, X101 connector, pin 2,
(O/R, 49-6 wire).
— Go to Step 2
Check Tilt Sensor
Circuit (Table 3-
12)
2. Check for ground on PHP circuit at MC-1 box, X105 connector, pin
12, (O/R, 49-1 wire).
—
Problem in MC-1
controller box
Check PHP
Switch Circuit
(Table 3-13)
Table 3-12. Tilt Sensor Circuit Check
• No ground at MC-1 box, X101 connector, pin 2, (O/R, 49-6 wire).
STEP ACTION SPEC YES NO
1. Is tilt sensor light on showing a tilt condition, even though machine is
within tilt limit.
—
Adjust tilt sensor
if necessary
Go to Step 2
2. Check for ground on the Black wire (direct to ground) running into tilt
sensor. (Continuity to B-)
— Go to Step 3
Repair
Connection
3. Check for 24 volts at the Green to (Y/R, 2-5) wire from the main con-
tactor relay.
— Go to Step 4
Check Connec-
tion to Main Con-
tactor Relay
4. Check for ground on the White to (O/R, 49-6) wire at connector.
—
Repair connec-
tion at the X101
connector end/
broken wire O/R
49-6
Replace
Tilt Sensor