Mercury V8 250 User Manual

Step Test Procedure Test Result
Step 6: Check the up
relay.
1. Connect the voltmeter red lead to
Point 4 (female bullet connector) and
black lead to ground.
2. Depress the up trim button.
Relay is good (battery voltage measured):
• Pump motor wiring is defective.
• Pump motor is defective.
Relay is faulty (no battery voltage measured):
• Replace relay.
Troubleshooting the Up Circuit
IMPORTANT: Refer to the preceding wiring diagram for connection points when troubleshooting the electrical systems.
Connection points are specified by number.
DMT 2004 Digital Multimeter 91‑892647A01
IMPORTANT: Perform the following tests with the engine off and the 14‑pin connector disconnected from the outboard. This
will isolate the outboard from the boat. If the engine tilts when using the cowl trim switch, the problem is related to the trim
switch at the helm.
NOTE: To access test points 2 and 8, partially remove the relay from the connector just far enough to reach the electrical
contacts with the voltmeter lead.
Step
Test Procedure Test Result
Step 1: Check for
battery voltage at
Point 5 by back
probing.
1. Connect the voltmeter black lead to
ground and the red lead to Point 5.
2. Depress the up trim button.
Battery voltage measured:
• Go to Step 2.
No battery voltage measured:
• Go to Step 3.
Step 2: Check for
battery voltage at
Point 8.
1. Connect the voltmeter black lead to
ground and the red lead to Point 8.
2. Depress the up trim button.
Battery voltage measured:
• Go to Step 5.
No battery voltage measured:
• There is an open circuit between Point 8 and the
PCM.
• Check for loose or corroded connections.
• Inspect the wiring harness for opens, shorts, or
damage. Repair or replace the harness.
Step 3: Check for
continuity between
Point 1 and Point 5.
1. Disconnect the 3‑pin connector.
2. Connect the voltmeter black lead to
Point 1 and the red lead to Point 5.
Continuity measured (resistance should be 5.6 kΩ ±
20%):
• Harness and PCM are OK.
• Go to Step 4.
No continuity measured (resistance should be 5.6 kΩ ±
20%):
• Inspect the wiring harness for opens, shorts, or
damage. Repair or replace the harness.
Step 4: Check for
battery voltage at
Point 6.
1. Connect the voltmeter red lead to
Point 6 and black lead to ground.
Battery voltage measured:
• Trim switch is faulty.
No battery voltage measured:
• Check for loose or corroded wire at Point 6.
• Open circuit in wire supplying current between Point
6 and Point 7.
Step 5: Check for
battery voltage at
Point 4.
1. Connect the voltmeter red lead to
Point 4 (female bullet connector) and
black lead to ground.
2. Depress the up trim button.
Battery voltage measured:
• Go to Step 6.
No battery voltage measured:
• Relay is defective.
Step 6: Check the
down relay.
1. Connect the voltmeter red lead to
Point 3 (female bullet connector) and
black lead to ground.
2. Depress the down trim button.
Relay is good (battery voltage measured):
• Pump motor wiring is defective.
• Pump motor is defective.
Relay is faulty (no battery voltage measured):
• Replace relay.
Advanced Midsection (AMS) Power Trim
Page 6D-6 © 2018 Mercury Marine 90-8M0146617 eng JULY 2018

Mercury V8 250 Specifications

General

Brand	Mercury
Model	V8 250
Category	Outboard Motor
Language	English