Troubleshooting the Down and Up Circuits (All Circuits Inoperative)
IMPORTANT: Numerical callouts shown in the circuit diagrams are test points. Refer to Troubleshooting the Down Circuit or
Troubleshooting the Up Circuit.
DMT 2004 Digital Multimeter 91‑892647A01
Problem Possible Cause Remedy
The up and down trim
switches are both
inoperative, but the cowl
switch does operate.
1. Faulty trim switch.
2. A wire is open between the trim
pump motor and the trim
switch.
1. Replace the trim switch.
2. Check for a loose or corroded connection.
Trim switch and cowl
switch are both
inoperative.
1. One of the trim pump motor
wires is open between the
motor and the relays.
2. A wire is open between the trim
pump motor and the trim
switch.
3. Faulty trim relay.
4. Faulty trim pump motor.
1. Check the wire connections at point 2 or 8 for loose or
corroded condition.
2. If voltage is present at the connections at point 2 or 8
when the appropriate trim button is pressed, the relays
are okay.
3. Check if voltage is present at point 3 or 4 when the
appropriate trim button is pressed. If voltage is not
present, check for an open connection or a cut wire.
4. If voltage is present at point 3 or 4 when the
appropriate trim button is pressed, replace the trim
pump motor.
Trim system operates
(trim motor runs) without
pressing the trim switch at
the helm or the cowl trim
switch.
The trim switch at the helm or the
cowl trim switch is shorted.
Disconnect each trim switch. If the trim motor stops running
when either trim switch is disconnected, replace the trim
switch.
Trim Circuit
When the trim relays are de‑energized, contacts 30 and 87a of both relays complete the circuit to the trim motor leads. Both
trim motor leads are to ground.
Advanced Midsection (AMS) Power Trim
90-8M0146617 eng JULY 2018 © 2018 Mercury Marine Page 6D-7
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