Mercury 75 Service Manual page 67

CDM Trouble Shooting Flowchart
Chart #2 (No Spark on any CDM)
Step Action
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
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
3 Check Trigger/Crank Shaft Posi-
tion Sensor Output:
Cranking with CDM disconnected.
Cranking with CDM connected.
4 V-6 Models
Resistance Check Crank Position
Sensor
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?
6 If mis-firing is in a repeatable
range:
Perform DVA readings on stator
and trigger at all running speeds.*
* 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.
90-830234R3 DECEMBER 1997
Value Yes
NO continuity Step 2
660-710 Step 3
Ohms
2, 3 & 4 Cyl.
Models
990 - 1210
Ohms 6 Cyl.
1 Volt and Step 5
above - CDM
disconnected.
0.2 - 5 Volts-
CDM
connected.
900 - 1300 Step 5
Ohms
7/16 in. Step 6
(11.11 mm)
gap
Stator: Run Engine
200 Volts and Verify Repair
above
END
Trigger:
2 Volts and
above
No Tools
Repair or DVA/Multimeter
Replace Com- P/N 91-99750
ponent
Run Engine
Verify Repair
Step 6
Replace DVA/Multimeter
Stator P/N 91-99750
Run Engine
Verify Repair
Step 6
2, 3, & 4 Cyl DVA/Multimeter
Replace Trig- P/N 91-99750
ger
TPI/CDM Test
Run Engine Harness
Verify Repair 84-825207A2
Step 6
6 Cyl. - Step 4
Replace DVA/Multimeter
Crank Posi- P/N 91-99750
tion Sensor
Run Engine
Verify Repair
Step 6
Verify All Pre- Spark Gap Tes-
ceding Steps ter P/N
91-850439
Refer to *Note DVA/Multimeter
Below P/N 91-99750
TPI/CDM Test
Harness
84-825207A2
ELECTRICAL - 2A-29