Evinrude E-tec 75 HP, Service Manual

Page: 139 / 344

139
ELECTRICAL AND IGNITION
TACHOMETER CIRCUIT TESTS
6
TACHOMETER CIRCUIT
TESTS
IMPORTANT:
Make sure all outboard and boat
wiring and connectors are in good condition.
Check voltage at the battery. Use this reading as
a reference for battery voltage.
STEP 1
Connect the red meter lead to the tachometer pur-
ple wire and the black meter lead to the tachome-
ter black wire (key ON, outboard NOT running).
•
If meter shows battery voltage, go to STEP 2 .
•
If meter shows less than battery voltage, check
the purple, red/purple, and black wiring circuits,
fuse, key switch, and battery connections.
STEP 2
Disconnect instrument harness gray wire and
black wire at tachometer. Set
Fluke
29 Series II
meter, or equivalent, to Hz scale. Connect meter
between gray wire and black wire. With outboard
running at 1000 RPM, meter should indicate 90 to
105 Hz.
•
If meter reads 90 to 105 Hz, replace tachome-
ter.
•
If meter reads low or no signal, confirm output
on gray wire at pin 16 of
EMM
J1-A connector.
– Reading OK – Check condition of tachometer
circuit (gray wire). Repair as needed.
– Reading not OK – Check connection at
EMM
;
replace faulty
EMM
.
1. Purple lead
2. Black lead
3. Gray lead
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