22773 Mercruiser LOCKWASHER, ROCKER COVER SCREW

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Schematic for the brake oil temperature sensor
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
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Left side engine view (typical example)
(1) J1/P1 ECM connector
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Left side engine view (typical example)
(2) J61 Customer connector
Thoroughly inspect connector (1) and (2). Also, thoroughly inspect any other connectors that are associated with the suspect sensor. Refer to Troubleshooting, "Electrical Connectors - Inspect".
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Terminal locations at the P1 ECM connector
(P1-4) +8 V Supply
(P1-5) Sensor return
(P1-14) Brake oil temperature
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Terminal locations at the J61 and the P61 connectors
(8) +8 V Supply
(9) Sensor return
(11) Brake oil temperature
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Sensor connector
(Terminal A) Supply voltage
(Terminal B) Sensor return
(Terminal C) Signal
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the suspect sensor.
Check the allen head screws on each of the ECM connectors for the proper torque. Also, check the allen head screw on the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points from the sensor to the ECM. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The connectors and the wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or the wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the repair eliminates the problem.STOPTest Step 2. Check the Supply Voltage to the Sensor
Turn the keyswitch to the OFF position.
Disconnect the brake oil temperature sensor.
Turn the keyswitch to the ON position.
Measure the voltage between pin A and pin B of the sensor connector on the engine harness. Expected Result:The supply voltage is 8.0 0.5 VDC.Results:
OK - The voltage is 8.0 0.5 VDC. The supply voltage is within the range. Proceed to Test Step 3.
Not OK - The voltage is not within specifications. The supply voltage is not available at the sensor. Proceed to Test Step 6.Test Step 3. Check the Signal Frequency at the Sensor
Turn the keyswitch to the OFF position.
Ensure that the brake oil temperature sensor is disconnected.
Insert a 7X-6370 Adapter Cable As (3-PIN BREAKOUT) between the connectors for the brake oil temperature sensor.
Turn the keyswitch to the ON position.
Measure the signal frequency between pin C and pin B of the breakout. Expected Result:The signal frequency measures 500 200 Hz.Results:
OK - The frequency is 500 200 Hz.Repair: The signal frequency is normal. Leave the breakout in the circuit.Proceed to Test Step 4.
Not OK - The frequency is not within the specifications.Repair: There may be a problem with the sensor. Temporarily connect a new sensor.If the new sensor eliminates the problem then reconnect the suspect connector in order to verify the repair.If the problem returns with the suspect sensor, permanently install the new sensor. Verify that the repair eliminates the problem.STOPTest Step 4. Check the Duty Cycle at the Sensor
Determine the temperature of the brake oil. If the temperature of the brake oil cannot be measured, remove the sensor. Allow the temperature of the sensor to stabilize to room temperature and use the ambient air temperature for the test.
Turn the keyswitch to the ON position.
Measure the duty cycle between pin C (signal) and pin B (return) of the breakout. Use the following table to validate the results.
Table 1
Temperature °C (°F) Duty Cycle (%)
−40 °C (−40 °F) 10.01
−30 °C (−22 °F) 10.48
−20 °C (−4 °F) 11.32
−10 °C (14 °F) 12.72
0 °C (32 °F) 14.97
10 °C (50 °F) 18.36
20 °C (68 °F) 23.17
30 °C (86 °F) 29.51
40 °C (104 °F) 37.22
50 °C (122 °F) 45.84
60 °C (140 °F) 54.70
70 °C (158 °F)