Mercury V8 300

ECT Sensor Resistance Test
Temperature Reading (nominal)
0 °C (32 °F) 32.6 kΩ
20 °C (68 °F) 12.5 kΩ
40 °C (104 °F) 5.3 kΩ
65 °C (150 °F) 2.1 kΩ
95 °C (203 °F) 786 Ω
4. Perform a continuity check of the sensor wiring between the sensor connector and the PCM. Note that there are splices in
the ground circuit.
NOTE: The quickest way to check the wiring is to measure the resistance of the thermistor at room temperature, connect
the sensor to the engine harness, and measure the resistance across PCM connector sockets CE1 and BE2. If the two
resistance values match, then the wiring is good.
DMT 2004 Digital Multimeter
91‑892647A01
Terminal Test Probe Kit Bosch P/N MM‑ 46523
a - Engine coolant temperature
(ECT) sensor connector
b - PCM connector B
c - PCM connector C
Connector Pin Wire Color Function PCM
53172
B
A
A Black/orange Sensor ground A (–) CE1
B Brown/black Engine coolant temperature signal BE2
ECT Sensor Removal
1. Cut the cable tie that secures the sensor harness connector to the engine harness.
2. Disconnect the sensor harness from the engine harness.
100A
100B
BLK/ORN
BRN/BLK
BRN/BLK
BLK/ORN
A
B
H4
E1
A1
E2
M4
A1
A B
C
D E F G H
J
K
AB
C
DEFGH
J
K
1
3
2
4
L
M
L
M
M
A
4
1
A
B
C
D
E
F
G
H
1
2
3
4
A
B
C
D
E
F
G
H
A
H
1
4
66023
a
b
c
Sensors
Page 5A-18 © 2018 Mercury Marine 90-8M0146617 eng JULY 2018