Wire Color Code Abbreviations
Wire Color Abbreviations
BLK Black
BLU Blue
BRN Brown GRA Gray
GRN Green ORN Orange
PNK Pink PPL Purple
RED Red TAN Tan
WHT White YEL Yellow
LT Light DK Dark
Warning System Wiring Diagram
a - Engine control module (ECM)
b - Warning horn
c - Warning light
Troubleshooting without a Computer Diagnostic System (CDS)
Troubleshooting without a computer diagnostic system (CDS) is limited to checking resistance on some of the sensors.
Typical failures usually do not involve the ECM. Connectors, setup, or mechanical wear are most likely at fault.
•
Verify the ignition coils are securely connected to the spark plugs.
• The engine may not run or may not run above idle with the wrong spark plugs installed.
• Swap ignition coils to see if the problem follows the coil or stays with the particular cylinder.
IMPORTANT: Disconnecting a sensor while the engine is running may result in a fault recording in the ECM Fault History. Use
the CDS to view the ECM fault history when troubleshooting/repair is completed.
• If all cylinders exhibit similar symptoms, the problem is with a sensor or harness input to the ECM.
• If a problem is speed related or intermittent, it is probably connector or contact related. Inspect connectors for corrosion,
loose wires, or pins pushed back into the connector. Verify the connectors are properly seated.
• Inspect the harness for damage: pinched or cut wires and chafing.
• Secure the grounds and all connections involving ring terminals. Apply Liquid Neoprene to all ring terminal connections.
Tube Ref No. Description Where Used Part No.
25
Liquid Neoprene All ring terminal connections 92- 25711 3
• Inspect the fuel pump electrical connector for corrosion, loose wires, or pins pushed back into connector.
•
Check the fuel pump pressure.
Troubleshooting with CDS G3
The ECM is designed such that if a sensor fails, the ECM will prevent the engine from going into an overly rich condition. This
means that disconnecting a sensor for troubleshooting purposes may have no noticeable effect, presenting the technician with
a difficult diagnostic challenge. To meet this challenge, Mercury Marine has developed the CDS G3 diagnostic tool.
About CDS G3
CDS G3 is a standalone program that provides diagnostic support for select Mercury engines and engine control systems.
CDS G3 also supports all configuration functions necessary for preparing these systems for delivery. CDS G3 provides a clean,
easy‑to‑navigate interface.
1
18
1734
17
1
10
3
2
4
5
6
7
13
15
12
11
14
16
9
8
34
18
27
20
19
21
22
23
24
30
32
29
28
31
33
26
25
1 2
YEL
BLU
LT GRN
YEL
BLU
WHT/RED
LT GRN
1
2
2
4
33
a
b
c
62885
General Troubleshooting
90-8M0125265 eng NOVEMBER 2017 © 2018 Mercury Marine Page 1E-7
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