Engine Coolant Temperature (Ect) Sensor - Mercury 15 EFI FourStroke Service Manual

Engine Coolant Temperature (ECT) Sensor

The engine coolant temperature sensor is located at the top of the cylinder block. The ECT sensor monitors the temperature of
the cooling water that has passed through the engine as controlled by the thermostat. The ECM uses the data from the ECT
sensor in its calculations for the amount of fuel to inject into the combustion chamber to achieve optimum fuel economy, based
on the engines RPM.
In the event of an overtemperature exceeding 85 °C (185 °F), the ECM will limit engine power, generate a failure code, and
complete the circuit for the warning horn and warning light, informing the operator of potential engine damage.
ECT Wiring Diagram
18
1
a
18 1
19 2
20 3
21 4
22 5
23 6
24 7
24
25 8
26 9
27 10 27
28 11
29 12
30 13
31 14
32 15
33 16
34 17
34 17
ECT Sensor Removal
1. Remove the air box and recoil starter.
• It is easiest to remove and install these two items together.
• Refer to Section 3C ‑ Air Box Removal and Section 8A ‑ Recoil Starter.
2. Release the reusable cable tie that secures the sensor lead to the electrical bracket.
3. Disconnect the ECT 2‑pin connector from the engine harness.
4. Use an appropriate wrench to remove the ECT sensor from the engine.
b
a
ECT Sensor Test
1. Place the ECT sensor in a container filled with water.
2. Place a thermometer in the water, and slowly heat the water.
90-8M0125265 eng NOVEMBER 2017
GRN/YEL
BLK/BLU
J2
21113
b
BLK/BLU 1
GRN/YEL 2
62904
a - ECT sensor
c
b - Flywheel
c - Engine lifting eye
62969
© 2018 Mercury Marine
a - ECM connector
b - ECT connector
Ignition
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