Mercury 90 Service Manual

5B-18 - MID-SECTION 90-830234R3 DECEMBER 1997
Troubleshooting the “Down” and “Up” Circuits* (All Circuits Inoperative)
*Remote Control NOT Equipped with Trailer Button
Battery Voltage Indicated:
• Connect Voltmeter red lead to Point
8 and black lead to ground.
• Depress “Up” trim button and check
for battery voltage.
No Voltage Indicated:
Red wire is open between Point 3 and red terminal
on back of the ignition switch.
• Check for loose or corroded connections.
• Check for open circuit in wire.
Battery Voltage Indicated:
• Check black ground wires for poor con-
nection or poor ground.
• Pump motor is faulty. Refer to “Motor and
Electrical Tests/Repair,” following.
Battery Voltage Indicated:
Trim switch is faulty or there is an open cir-
cuit in wires (green-white, blue-white) be-
tween trim buttons and trim pump.
• Check trim switch.
• Check all trim harness connectors for
loose or corroded connections.
• Check for pinched or severed wires.
Battery Voltage Indicated:
There is an open circuit in wire between
Point 5 and Red terminal on the back of the
ignition switch.
No Voltage Indicated:
Check that voltage is being supplied to control
by performing the following checks:
• DO NOT start engine.
• Turn ignition switch to “Run” position.
• Check for voltage at any instrument, us-
ing a Voltmeter.
No Voltage Indicated:
Connect red Voltmeter lead to Point
5, and black lead to ground.
No Voltage Indicated:
• Check battery leads for poor
connections or open circuits.
• Check battery charge.
Blown Fuse:
• Correct problem that
caused fuse to blow.
• Replace fuse.
Fuse Not Blown:
Connect Voltmeter red lead to Point 3
and black lead to ground, Battery volt-
age should be indicated.
Check in-line fuse (under cowl) to see if fuse is blown

Mercury 90 Specifications

General

Brand	Mercury
Model	90
Category	Outboard Motor
Language	English