Transmission Solenoid Valves - JLG sky trak mmv Service Manual

10.13.8

Transmission Solenoid Valves

The transmission is shifted via six solenoids. Three sole-
noids valves Y1, Y2, and Y3 are contained in an UPPER
spool-type solenoid cartridge assembly (valve body) (6).
The remaining three solenoid valves Y4, Y5 and Y6 are
contained in the LOWER spool-type solenoid cartridge
assembly (valve body) (7). While each 12-volt solenoid
coil at the transmission is the same, the internal wiring to
the solenoids is different and connected so that the vari-
ous transmission clutches can be actuated via input from
the transmission shift control switch (travel select lever).
By placing the transmission shift control switch (travel se-
lect lever) in any given position a combination of sole-
noids is activated, which in turn engages a set
combination of internal clutches. (Refer to Section
10.13.8, b. Travel Select Lever and Wiring Harness Test-
ing and Section 10.13.8, c. Upper and Lower Transmis-
sion Valve Body Solenoid Testing .)
7
Model MMV Rev. 12/04
6
MT2280
If the transmission is not shifting properly, the transmis-
sion shift control switch (travel select lever), dash panel,
wiring harness or transmission shift solenoids should be
checked in order to determine which component is defec-
tive. Specific information to determine which travel posi-
tion and corresponding component is not responding can
be found by referring to Section 10.8.1, Transmission,
Forward - First Gear Circuit and subsequent circuits and
troubleshooting charts. Replace a defective component.
a. Travel Select Lever and Dash Panel Testing
If the transmission is not shifting properly, it must be
determined which component is defective. The following
test will determine if the problem is in the travel select
lever or dash panel.
Turn the ignition switch to the RUN position. Move the
travel select lever to the FORWARD [F], REVERSE [R]
and NEUTRAL [N] positions (8) and through each gear
selection. Note that the corresponding dash panel shift in-
dicators (9) are activated. If the dash panel lights are
working properly, the problem is in the transmission har-
ness or the transmission shift solenoids.
Electrical System
9
8
MM2001
10.145