JLG sky trak mmv Service Manual page 527

Before troubleshooting any
electrical circuit, ALWAYS
begin by checking the
following:
1. Fuses
2. All connections relating
to circuit are clean and
tight
Model MMV Rev. 12/04
All four wheels steer with
the steer select switch in
the 2 wheel mode.
Check circuits 19B (YEL/BLK)
and 18B (GRY/GRN)
for battery voltage at steer
select valve mounted on
hydraulic tank. Should
read "0" volts.
If OK
Refer to 9.7, Hydraulic
System Testing and perform
steering relief test.
If OK
Replace steer select valve.
Electrical System
Not
Replace steer select switch.
OK
10.47