Mercury 90 Service Manual

90-830234R3 DECEMBER 1997 ELECTRICAL - 2A-29
CDM Trouble Shooting Flowchart
Chart #2 (No Spark on any CDM)
Step
Action Value Yes No Tools
1 With the key switch ON:
Verify continuity between BLK/YEL
harness wire and ground.
This Test Checks:
Lanyard Switch
Key Switch
Rev Limiter (external)
Chafed BLK/YEL wire
CDM Stop Circuit
NO continuity Step 2 Repair or
Replace Com-
ponent
Run Engine
Verify Repair
Step 6
DVA/Multimeter
P/N 91-99750
2
Check Stator
Resistance between GRN/WHT
and WHT/GRN
Open circuit voltage at cranking
should be no less than 100 Volts
on the DVA
660-710
Ohms
2, 3 & 4 Cyl.
Models
990 - 1210
Ohms 6 Cyl.
Step 3 Replace
Stator
Run Engine
Verify Repair
Step 6
DVA/Multimeter
P/N 91-99750
3
Check Trigger/Crank Shaft Posi-
tion Sensor Output:
Cranking with CDM disconnected.
Cranking with CDM connected.
1 Volt and
above - CDM
disconnected.
0.2 - 5 Volts-
CDM
connected.
Step 5 2, 3, & 4 Cyl
Replace Trig-
ger
Run Engine
Verify Repair
Step 6
6 Cyl. - Step 4
DVA/Multimeter
P/N 91-99750
TPI/CDM Test
Harness
84-825207A2
4 V-6 Models
Resistance Check Crank Position
Sensor
900 - 1300
Ohms
Step 5 Replace
Crank Posi-
tion Sensor
Run Engine
Verify Repair
Step 6
DVA/Multimeter
P/N 91-99750
5
Test all CDMs at Cranking with
Spark Gap Tester
Spark on All CDMs?
Will spark jump a 7/16 in.
(11.11 mm) gap?
7/16 in.
(11.11 mm)
gap
Step 6 Verify All Pre-
ceding Steps
Spark Gap Tes-
ter P/N
91-850439
6
If mis-firing is in a repeatable
range:
Perform DVA readings on stator
and trigger at all running speeds.*
Stator:
200 Volts and
above
Trigger:
2 Volts and
above
Run Engine
Verify Repair
END
Refer to *Note
Below
DVA/Multimeter
P/N 91-99750
TPI/CDM Test
Harness
84-825207A2
* Note: Stator tests will only isolate problem down to
a charging pair. Further testing is necessary to deter-
mine faulty CDM. Disconnecting one CDM of the
charging pair is recommended.

Mercury 90 Specifications

General

Brand	Mercury
Model	90
Category	Outboard Motor
Language	English