9101F4-5640 Tohatsu BOLT

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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 at the probe of the sensor. The sensor contains a probe (2) that is covered with plastic (3) .When the sensor's 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, approximately +5 VDC is sourced to the signal wire. When this condition is detected by the Electronic Control Module (ECM), an event code is activated.Prior to troubleshooting any problems with the coolant level sensor, use Caterpillar Electronic Technician (ET) to check the installation status for the sensor. The coolant level sensor's configuration parameter must be set to "Installed" in order for the ECM to monitor the signal from the sensor.The activation of an event code and/or a warning lamp is probably caused by a low coolant level. The next likely cause is a problem with the wiring harness, a connector, or the sensor. The least likely cause is a problem with the ECM.
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Schematic for the engine coolant level sensor
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Schematic for the coolant level sensor of the aftercoolerTest Step 1. 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.
Remove electrical power from the ECM.Note: Allow the engine to cool prior to removal of the cooling system pressure cap.
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 2.
Not OK - The coolant level is low.Repair: Add coolant according to the procedure in the Operation and Maintenance Manual.There may be a leak in the cooling system. Identify the source of the coolant leak. Repair the leak.STOPTest Step 2. Verify that the Parameter for the appropriate "Coolant Level Sensor" is Programmed Correctly
Remove electrical power from the ECM.
Connect the Cat ET to the service tool connector.
Restore electrical power to the ECM.
Establish communication with the ECM.
Verify that the parameter for the suspect "Coolant Level Sensor" is programmed to "Installed".
Remove electrical power from the ECM.Expected Result:The suspect "Coolant Level Sensor" parameter is programmed to "Installed".Results:
OK - The "Coolant Level Sensor" parameter is programmed correctly. Proceed to Test Step 3.
Not OK - The "Coolant Level Sensor" parameter is not programmed correctly.Repair: Program the "Coolant Level Sensor" parameter to "Installed".Verify that the repair eliminates the problem.STOPTest Step 3. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
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Top front engine view with a heat exchanger (4) Engine coolant level sensor
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Top front engine view with an expansion tank. (4) Engine coolant level sensor (5) Coolant level sensor for the aftercooler
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Location of the ECM connectors (back engine view) (6) J2/P2 connectors
Thoroughly inspect the connectors for sensor (4). Also, thoroughly inspect ECM connectors (5). Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
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Terminal locations for the P2 ECM connector (P2-29) Sensor supply (P2-49) Coolant level (P2-92) Sensor return
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Harness connector for the coolant level sensor (Terminal A) Sensor supply (Terminal B) Sensor return (Terminal C) Sensor signal
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