Mercury V6 175 Diagnostic Manual page 8

How to Use This Manual
Models Covered
This diagnostic manual provides service technicians with information relating to Mercury outboard engines that use the PCM
112 electronic control unit. At the time of this publication, that includes 175–300 hp FourStroke, Pro XS, SeaPro, and Verado
models.
Mercury 175 V6, 175 V6 Pro XS, 200 V6, 200 V6 SeaPro, 225 V6
Mercury 200 V8 Pro XS, 225 V8 Pro XS, 225 V8 SeaPro, 250 V8, 250 V8 Pro XS, 250 V8 SeaPro,
250R V8, 300 V8, 300 V8 Pro XS, 300 V8 SeaPro, 300R V8
PCM label: The number in the lower left identifies the controller: PCM 112. The next two digits are the year it was introduced.
Manual Organization
Section 1 ‑ Important Information
The following comprise Section 1.
Section 1A ‑ How to Use This Manual.
Section 1B ‑ System Theory gives an overview of the speed/density theory and how it relates to open‑loop and closed‑loop
control. This section also covers the oxygen sensor used on PCM 112 engines and how it gives precise control over fueling.
Section 1C ‑ Emissions provides an overview of the emission control process.
Section 1D ‑ Glossary, Reference Charts, and Conversions.
Section 2 ‑ PCM 112
The following comprise Section 2.
Section 2A ‑ PCM 112 Important Information and Pinouts provides an overview of the PCM 112 and discusses
recommended test equipment. The PCM 112 pinout diagrams list the function and wire color of each pin in the PCM 112
module.
Section 2B ‑ PCM 112 and Engine Control Overview focuses on how faults are generated, and the steps involved when the
engine starts and enters into closed‑loop control.
Section 3 ‑ General Troubleshooting and CDS G3
The following comprise Section 3.
Section 3A ‑ General Troubleshooting discusses the audio warning system, and general approaches for addressing MFD
faults.
Section 3B ‑ Troubleshooting with the Computer Diagnostic System (CDS G3) contains information on connecting the
CDS G3 system to your PCM 112, as well as the different screens, information, and functions available to the technician.
Section 3C ‑ CDS G3—Live Data covers the information available to the technician on CDS G3's live data screen—the data
fields, a description of the data field, and typical data values—all useful information to provide a snapshot of what the engine is
doing at this moment.
Section 3D ‑ CDS G3—PCM 112 Freeze Frame Data provides an overview of the freeze frame data screen. The freeze frame
data screen provides a snapshot of the engine at the time a fault occurred.
Page 1A-2
Models Covered
P/N:
VPEDVU-12A650-CA
S/N:
PCM112-17-311
The last three numbers are an internal cross-reference number.
© 2018 Mercury Marine
1751-6685
8M6005749
*XXXXXXXXXXXX*
29180308
Serial Number or Year
2018 and Newer
2018 and Newer
67721
90-8M0146617 eng JULY 2018