3B2W64513-0 Tohatsu PROPELLER (6.5), 3 X 8.5 X 6.5

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Coolant level sensor (1) Sensor (2) Sensor probe (brass dowel) (3) Plastic coverCoolant level sensor (1) contains no moving parts. The sensor provides the same function as a switch. The state of the switch is dependent on the capacitance value that is detected. The sensor contains a probe (2) that is covered with plastic (3) .When the probe is immersed in coolant, the sensor senses a particular capacitance. The sensor's electronics react by sinking the signal to the digital return (ground).When the probe is not immersed in coolant, the capacitance value changes. The change in the capacitance value is detected by the sensor's electronic circuits. The sensor sources approximately +5 VDC to the signal wire. The Electronic Control Module (ECM) detects the voltage and the ECM activates an event code.Note: This feature is optional and the system configuration parameter for "Coolant Level Sensor" must be configured to "Installed". If the ECM parameter is not programmed, the engine monitoring system will not monitor the status of the sensor. Refer to Troubleshooting, "System Configuration Parameters".The event code for low coolant level is used to indicate that an abnormal condition exists for the engine. A low coolant level may cause damage to the engine. Correct this condition immediately.The most likely cause of an active diagnostic code that is related to the coolant level sensor is a loose connection in a connector. The next likely cause is a problem with the coolant level sensor or a problem with a wiring harness. The least likely cause is a problem with the ECM.
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Typical location of the coolant level sensor (4) Coolant level sensor
Illustration 3 g03428338
Schematic for coolant level sensorTest Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
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Engine view (5) J1/P1 ECM connectors
Thoroughly inspect connectors (5) . Also, thoroughly inspect the connectors for sensor (4) . Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
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P1 ECM connector (P1-4) +8 V digital supply (P1-5) Sensor return (P1-49) Coolant level sensor
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Harness connector for the coolant level sensor (A) +8 V digital supply (B) Sensor return (C) Coolant level sensor
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the coolant level sensor.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - The connectors and wiring are OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or the wiring.Repair: Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Supply Voltage at the Sensor Connector
Disconnect the coolant level sensor at the sensor connector.
Turn the keyswitch to the ON position.
Measure the voltage between terminals A (+8 V digital supply) and B (sensor return) at the harness connector for the coolant level sensor.
Turn the keyswitch to the OFF position.Expected Result:The voltage measurement is 8.0 0.4 VDC.Results:
OK - The voltage measurement is 8.0 0.4 VDC. The supply voltage is reaching the sensor. Proceed to Test Step 3.
Not OK - The voltage measurement is not 8.0 0.4 VDC. The digital sensor supply voltage is not reaching the sensor.Repair: Refer to Troubleshooting, "Digital Sensor Supply Circuit - Test".STOPTest Step 3. Check the Coolant Level
Pressurized System: Hot coolant can cause serious burns. To open the cooling system filler cap, stop the engine and wait until the cooling system components are cool. Loosen the cooling system pressure cap slowly in order to relieve the pressure.
Stop the engine.
After allowing the engine to cool, check the coolant level. Refer to the Operation and Maintenance Manual for the proper procedure to check the coolant level.Expected Result:The coolant is at the proper level.Results:
OK - The coolant is at the proper level. Proceed to Test Step 4.
Not OK - The coolant level is low.Repair: Add coolant according to the procedure in the Operation and Maintenance Manual.Verify that the repair eliminates the problem. Identify the source of the coolant leak and fix the problem.STOPTest Step 4. Disconnect the Coolant Level Sensor and Monitor the Status of "Coolant Level"
Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Disconnect the J800/P800 connectors.
Turn the keyswitch to the ON position.
Monitor the status of "Coolant Level" on Cat ET.
Turn the keyswitch to the OFF position.Expected Result:The status changes from "OK" to "Low" when the sensor is disconnected.Results:
OK - The status is "Low" when the sensor is disconnected. Proceed to Test Step 5.
Not OK - The status is "OK" when the sensor is disconnected. Proceed to Test Step 6.Test Step 5.