Chapter Fifteen
Power Trim and Tilt System
Tdmming descdbes a change in the angle
of the stem ddve in the water relative to the
bottom of the boat. Moving the stem ddve
away from the transom (tdmming out) raises
the bow in the water; moving it toward the
transom (tdmming in) lowers the bow. See
Figure 1.
Tdmming may be performed with the boat
at rest or at any speed in FORWARD gear. It
is generally done before accelerating onto
plane, after obtaining the desired engine rpm
or boat speed, or when there is a change in
the condition of the boat or water affecting
performance. Proper tdmming assures
maximum performance under any given load
and speed condition.
Use the bow-up position (trim out) for
cruising, running with choppy waves or
running at wide-open throttle. Too much bowup trim causes propeller ventilation which
results in propeller slippage.
Use the bow-down position (tdm in) for
accelerating onto plane, running at slow
planing speeds or running against choppy
waves. When bow-down tdm is excessive and
the boat is operated at high speeds, the bow
will plow into the water and make handling
difficult.
Tdmming will not correct handling
problems resulting from an overloaded boat
or a boat whose load is improperly balanced
as a result of incorrect placement.
The tilt feature is generally used to obtain
sufficient clearance when moodng, launching
the boat from a trailer or to provide adequate
clearance dudng beaching. The ddve may
also be tilted to reduce draft for shallow water
running, as long as engine speed does not
exceed 1,000 rpm. You should also make
sure that the lower gearcase water intakes are
under water at all times when running with a
tilt in shallow water. Tilting should only be
performed at idle speed or at rest.
All Cobra ddves are equipped with an
electro-hydraulic tdm/tilt system. An electdc
motor operates the hydraulic pump to
provide pressure for raising or lowedng the
hydraulic actuators (tdm/tilt cylinders). A
malfunction of the tdm/tilt system can result
in the loss of reverse thmst operation and
POWER TRIM AND TILT SYSTEM
469
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may cause of lack of shock absorbing
protection in the event an underwater object
is struck.
This chapter covers removal/installation
and troubleshooting of the power trim/tilt
system. Table 1 and Table 2 (Hydraulic
Pressure Specifications) and Table 3 and
Table 4 (Troubleshooting Diagnostics) are at
the end of the chapter.
SYSTEM COMPONENTS
The Cobra power trim/tilt system consists
of a valve body, oil pump and electric motor
contained in a single pump housing (Figure
2, 1986-1988 models or Figure 3, 1989-on
models). The pump housing is connected to
a hydraulic cylinder on each side of the drive
unit by hydraulic lines (Figure 4). A sending
unit is installed on the starboard side of the
gimbal ring (Figure 5). The sending unit is
electrically connected to a trim gauge on the
instrument panel or dash. The trim gauge
shows the bow position according to the trim
angle of the drive unit. A switch installed on
the remote control handle (if so equipped) or
on the instrument panel/dash controls the
trim/tilt operation through an UP solenoid or
a DOWN solenoid mounted on the engine on
1986-1988 models and through a relay and
circuit breaker assembly on 1989-on models.
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CHAPTER FIFTEEN
470
System is protected by two 50 amp fuses and
two 20 amp fuses on 1986-1988 models and
by two 50 amp fuses, a 20 amp fuse and a
circuit breaker located in the relay and circuit
breaker assembly on 1989-on models.
A manual release valve on the pump
housing can be used to lower the drive unit if
an electrical malfunction occurs. When the
valve is opened (turned counterclockwise),
the weight of the drive unit will force it back
to a vertical position.
Figure 6 shows the power trim/tilt system
used with 1986-1988 GM engines; Figure 7
shows the system used with 1989-on GM
engines; Figure 8 shows the system used with
1987-1988 Ford engines; Figure 9 shows the
system used with 1989-on Ford engines.
ELECTRICAL SYSTEM
Troubleshooting
If the power trim/tilt system will not
operate, refer to Figure 6 (1986-1988 GM
engines). Figure 7 (1989-on GM engines),
Figure 8 (1987-1988 Ford engines) or Figure
9 (1989-on Ford engines) as appropriate and
check the electrical system with the following
procedure. The fuses are located at the port
(2.3L) or starboard (2.5L/3.0L) side of the
block or at the rear of the intake manifold
(all others).
1. Make sure the battery is fully charged and
that the connections are clean and tight.
2. Turn the ignition switch ON, but do not
start the engine.
3A. 1986-1988-Check the condition of the
50 amp fuses between the assist solenoid,
trim/tilt solenoid and the starter motor. If the
fuses are good, check for battery voltage at
the fuse holders with a voltmeter or 12-volt
test lamp. If battery voltage is not shown,
check for a problem in the wiring between the
fuse holders and the battery.
3B. 1989-on—Check the condition of the 50
amp fuses between the assist solenoid, relay
and circuit breaker assembly and the starter
motor. If the fuses are good, check for battery
voltage at the fuse holders with a voltmeter
or 12-volt test lamp. If battery voltage is not
shown, check for a problem in the wiring
between the fuse holders and the battery.
4A. 1986-1988-Check the condition of the
20 amp fuse between the trim/tilt solenoids
and trim/tilt switch with a voltmeter or
12-volt test lamp. If the fuse is good, check
for battery voltage at the trim/tilt svntch. If
battery voltage is not shown, check for a
problem in the wiring between the fuse holder
or trim/tilt solenoids and the trim/tilt switch.
Check the solenoids as described in this
chapter.
4B. 1989-on—Check the condition of the
internal circuit breaker in the relay and circuit
breaker assembly with a voltmeter or 12-volt
test lamp. Battery voltage should be present
at both red/purple wire terminals on the relay
and circuit breaker assembly. If the circuit
breaker is good, check for battery voltage at
the trim/tilt switch. If battery voltage is not
shown, but supply voltage is present, then
replace relay and circuit breaker assembly.
5A. 1986-1988-Unplug the tdm/tilt motor
harness connector. Check for battery voltage
at the switch side of the connector with a