Sensor Tests; Swapping Sensors; General Sensor Troubleshooting - Mercury V6 175 Diagnostic Manual

Sensors
Lubricants, Sealants, Adhesives
Tube Ref No.
Extreme Grease
Special Tools
DMT 2004 Digital Multimeter
H z TEMP
m A
A
V
H z
mV
IG
OFF
IP
TEMP
A m A
C O M V H z
Terminal Test Probe Kit
CDS G3 Interface Kit
Oxygen Sensor Socket

Sensor Tests

IMPORTANT: The propulsion control module (PCM) is a highly dependable device and should not be replaced before testing
the sensor or wiring harness. Given the corrosive operating environment and heavy vibrations to which marine engines are
subjected, the highest occurrences of electrical problems are with the engine harness or the sensors themselves.

Swapping Sensors

The quickest and easiest ways to test a sensor are to either replace it with a known good sensor or to monitor the signal
voltage to determine if it varies as expected. While actual sensor values may differ from engine to engine, different sensor
types will always behave in predictable ways. For instance, the voltage drop across a temperature sensor will always vary
according to applied temperature.

General Sensor Troubleshooting

When trying to troubleshoot a sensor, try to narrow the fault to the wiring harness or the sensor. Typically, the propulsion
control module (PCM) is not the source of the fault. Replacing the PCM might appear to fix an issue, but the very act of
disconnecting and reconnecting components can reposition a connector with a broken wire (intermittent connection) or even
clean corrosion from a connector that is the actual cause of a fault.
Page 5A-2
Description
Measures RPM on spark ignition (SI) engines, ohms, amperes, AC and DC
voltages; records maximums and minimums simultaneously, and accurately
reads in high RFI environments.
4516
Test probes adapt test meter leads to harness connections without damaging
harness terminals. May be used with Computer Diagnostic System (CDS).
7915
CDS G3 License Key, Interface, Adapter, and Harness
66165
Aids in the removal and installation of oxygen sensors.
32314
© 2018 Mercury Marine
Where Used
Camshaft position sensor O-ring
91‑892647A01
Bosch P/N MM‑ 46523
8M0138392
Obtain from Local Tool Supplier
Part No.
8M0071842
90-8M0146617 eng JULY 2018