Mercury MERCRUISER Service Manual

Chart T4: Ignition System Test
Step Action Yes No
1
• Connect an analog tachometer to the auxiliary tachometer lead
located near the PCM.
• Try to start the engine.
• Turn the ignition key switch off.
Was there any tachometer signal on the analog tachometer
while cranking the engine?
Go to step 2.
Confirm tach link configured
correctly.
Engine mechanical problem,
refer to Section 3 ‑ Engine
Mechanical.
2
Check the spark plug wires for open circuits, cracks in the insulation,
or improper seating of the terminals at the spark plugs and coil
tower.
Was a problem found?
Locate and repair
or replace.
Retest the system.
Go to step 3.
3
Check for adequate spark at all of the spark plugs.
Was adequate spark present?
Go to step 4. Go to step 5.
4
Check the spark plugs for damage and wear.
Was a problem found?
Replace with a new
spark plug gapped
correctly.
Go to step 10.
5
• Turn the ignition key switch on.
• Using the DMT, check for B+ at the coil connector A.
• Turn the ignition key switch off.
With the ignition key on, was B+ present?
Go to step 6.
Locate and repair the open in
the harness.
Retest the system.
6
Check for continuity between the coil harness connectors B and C,
and the coil driver harness connector D.
Was continuity present?
Go to step 7.
Locate and repair the open in
the harness.
Retest the system.
7
• Turn the ignition key switch on.
• Using the DMT, check for B+ at the coil driver harness
connector A.
• Turn the ignition key switch off.
With the ignition key on, was B+ present?
Go to step 8.
Locate and repair the open in
the harness.
Retest the system.
8
Check continuity between the coil driver harness connector C and
the engine ground.
Was continuity present?
Go to step 9.
Locate and repair the open in
the harness.
Retest the system.
9
Check continuity between the coil driver harness connector B and
the PCM connector pin A‑4A.
Was continuity present?
Replace the coil
and coil driver.
Retest the system.
Locate and repair the open in
the harness.
Retest the system.
10
• Disconnect the harness from the crankshaft position sensor
(CPS).
• Turn the ignition key switch on.
• Using a DMT, check for 5 V at the harness connector.
a. Connect the red meter lead to the gray wire (pin 3).
b. Connect the black meter lead to the black/pink wire (pin 2).
• Turn the ignition key switch off.
With the ignition key on, was 5 V present?
Go to step 11.
Locate and repair the open in
the harness.
Retest the system.
11
Check continuity between CPS harness connector B and engine
ground.
Was continuity present?
Go to step 12.
Locate and repair the open in
the harness.
Retest the system.
12
Check continuity between CPS harness connector C and PCM
harness connector B‑4H.
Was continuity present?
No problem found.
Retest the system.
Locate and repair the open in
the harness.
Retest the system.
Troubleshooting
90-8M0099748 eng DECEMBER 2015 © 2016 Mercury Marine Page 1D-21

Mercury MERCRUISER Specifications

General

Brand	Mercury
Model	MERCRUISER
Category	Engine
Language	English