Mercury 25 EFI Service Manual page 385

Test for Ground
1. Use a DMT 2004 Digital Multimeter or ohmmeter (R x 1 scale). Place one lead of meter on the armature shaft and the
other lead on the commutator. If continuity is indicated, armature is grounded and must be replaced.
d
DMT 2004 Digital Multimeter
Red
Commutator
Checking and Cleaning Commutator
1. Inspect the commutator. If the commutator is worn, it can be turned down on an armature conditioner tool or on a lathe.
2. Clean the commutator with number 00 sandpaper.
Field Tests
IMPORTANT: The commutator end of the armature must be installed in the brushes when performing the following tests.
DMT 2004 Digital Multimeter
Meter Test Leads
Red
Green motor wire
Green motor wire
Blue motor wire
1. If specific readings are not obtained, check for:
• Defective armature
• Dirty or worn brushes
• Dirty or worn commutator
2. If defective components are found, repair or replace the component and retest.
90-8M0105568 eng MARCH 2016
a
c
b
11421
Meter Test Leads
Black
Armature shaft
Black
Blue motor wire
Motor bracket
Motor bracket
a - DMT 2004 Digital Multimeter
b - Armature
c - Commutator
d - Armature shaft
Meter Scale
R x 1
91‑892647A01
Meter Scale
R x 1
R x 1
R x 1
© 2016 Mercury Marine
91‑892647A01
Reading (Ω)
No continuity (OUCH)
Reading (Ω)
0
No continuity (OUCH)
No continuity (OUCH)
Power Trim
Page 5B-23