GROVE Published 1-20-2017, Control# 483-02 7-11
CD5515-2/YB5515-2 SERVICE MANUAL TRANSMISSION AND TORQUE CONVERTER
Electrical Troubleshooting
System Operation
Each powershift transmission is provided with electrical
safety locks which inhibit inadvertent operation of the crane
while in an unsafe condition.
When the parking brake is ENGAGED the crane is
prevented from moving by “dumping” oil in the transmission’s
oil system to the internal oil reservoir. No oil is directed to any
of the drive mechanisms, thereby inhibiting crane
movement. When DISENGAGED the crane will only start
when the shift control lever is in the NEUTRAL position.
Change of crane travel direction is accomplished by moving
the shift control lever, located on the steering column, from
Neutral (center) position up to the FORWARD position or
down to the REVERSE position. Change of speed range is
accomplished by rotating the shift control handle
COUNTERCLOCKWISE to increase the travel speed range
or CLOCKWISE to decrease the travel speed range.
Movement of the shift control lever and rotation of the shift
control handle energizes combinations of solenoid valves
through the ECU, which are connected to two shafts located
in the transmission (See Table 7-1).
Transmissions are furnished with six solenoid valves (SV1,
SV2, SV3, SV4, SV5 and SV6) See arrangement in
Figure 7-9. Two of the solenoid valves control speed ranges
while the remaining four control speed and the direction of
travel.
The solenoids are controlled by the transmission Electronic
Control Unit (ECU) and are connected through the wire
harness.
Table 7-1 shows which solenoid valves are energized for the
four speeds and two directions of travel.
Electronic Control Unit (ECU)
The Electronic Control Unit (ECU) is designed to do two
things Figure 7-10:
• To control the selection of gears and direction of travel.
• To protect the gearbox from damage due to incorrect
use of the controls.
It is a microprocessor controlled unit which is mounted in the
battery compartment. A wire harness connects the ECU to
the transmission harness, which connects to the solenoids,
the oil pressure switch and a speed sensor, on the
transmission. A second harness connects the unit to various
switches and selectors in the cab.
The unit receives signals from the gear/direction and other
switches in the cab and operates the appropriate
transmission solenoids accordingly. Built-in software
prevents potentially damaging (and dangerous) selections
from being made. The control features provided by the ECU
software are listed below:
1. Downshift Inhibit - prevents too low of a gear being
selected for a given speed.
2. Kickdown - operated by a button on the shift lever in the
cab - changes down a gear (from 2nd, 3rd or 4th) for a
period of 6 seconds before reverting to the selected
gear.
3. Reverse Inhibit - prevents directional changes if the
speed is too high.
4. Neutral Start - the machine will only start with the shift
control handle in neutral, irrespective of gear selection
(speed) position.
FIGURE 7-9
HIGH
MAIN
SHAFT
LOW
LOW
LAY
SHAFT
HIGH
Table 7-1: Solenoid Valve Energizing Sequence
GEAR DIRECTION VALVES
First Forward SV6 and SV3
Second Forward SV5 and SV3
Third Forward SV6 and SV4
Fourth Forward SV5 and SV4
First Reverse SV1 and SV3
Second Reverse SV2 and SV3
Third Reverse SV1 and SV4
Fourth Reverse SV2 and SV4
Reference Only
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