Mercury 75 Service Manual page 388

Troubleshooting the Power Trim Electrical System
Refer to wiring diagram on preceding page for location of wire connections.
Problem
Trim Switch "UP" is inoperative,
but the Cowl Switch "UP" does
operate.
Cowl Switch "UP" is inoperative,
but the Trim Switch "UP" does
operate.
Trim Switch "UP" and Cowl
Switch "UP" are both inoperative.
Trim Switch "DOWN" is
inoperative, but the Cowl Switch
"DOWN" does operate.
Cowl Switch "DOWN" is
inoperative, but the Trim Switch
"DOWN" does operate.
Trim Switch "DOWN" and Cowl
Switch "DOWN" are both
inoperative.
Trim Switch "UP" and "DOWN"
are both inoperative, but the
Cowl Switch does operate.
Trim Switch and Cowl Switch are
both inoperative.
Trim system operates (motor
runs) without pressing the
switches.
5C-28 - MID-SECTION
Possible Cause
1. Open wire between Wire Connection (1) and
Trim Switch.
2. Faulty Trim Switch.
1. Open wire between Wire Connection (2) and
Solenoid.
2. Faulty Cowl Switch.
1. Open wire between Wire Connection (1) and
the Up Relay.
2. Open BLK wire between ground and UP
Relay.
3. Open RED wire between Solenoid and Up
Relay.
4. Faulty Up Relay .
1. Open wire between Wire Connection (3) and
Trim Switch.
2. Faulty Trim Switch.
1. Open wire between Wire Connection (2) and
Solenoid.
2. Faulty Cowl Switch.
1. Open wire between Wire Connection (3) and
the Up Relay.
2. Open BLK wire between ground and Down
Relay.
3. Open RED wire between Solenoid and Down
Relay.
4. Faulty Down Relay
1. 20 AMP Fuse blown.
2. Faulty trim switch.
3. Wire is open between fuse holder and
solenoid.
4. Wire is open between fuse holder and trim
switch.
1. One of the Trim Pump Motor wires is open
between the motor and the Relays.
2. Faulty trim pump motor.
1. The Trim or Cowl switch is shorted.
Remedy
1. Check for a open connection or cut wire.
2. Replace
1. Check for a open connection or cut wire.
2. Replace
1. Check for an open connection.
2. Check for an open connection.
3. Check for an open connection.
4. Replace
1. Check for a open connection or cut wire.
2. Replace
1. Check for a open connection or cut wire.
2. Replace
1. Check for an open connection.
2. Check for an open connection.
3. Check for an open connection.
4. Replace
1. Replace fuse. Locate the cause of the
blown fuse. Check electrical wiring for a
shorted circuit.
2. Replace
3. Check for a open connection or cut wire.
4. Check for a loose or corroded connection.
1. Check wire connections (4) for loose or
corroded condition.
2. If voltage is present at connections (4)
when the appropriate trim button is pressed,
than motor is faulty. Replace motor.
1. Replace
90-830234R3 DECEMBER 1997