3BJ-06060-1 Tohatsu CD UNIT

Illustration 1 g01150024
Coolant level sensor
(1) Sensor
(2) Sensor probe (brass dowel)
(3) Plastic cover Coolant 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 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.
Illustration 2 g01381926
Schematic for coolant level sensor
The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.
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.
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
Illustration 3 g01365227
Location of the coolant level sensor (typical left front engine view)
(4) Coolant level sensor
Illustration 4 g01388281
Location of the ECM connectors (typical engine view)
(5) J1/P1 connectors
Thoroughly inspect the connectors for sensor (4). Also, thoroughly inspect ECM connectors (5). Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 5 g01381925
P1 terminals that are associated with the engine coolant level sensor
(P1-5) Return
(P1-4) +8 VDC (digital sensor supply)
(P1-49) Engine coolant level
Illustration 6 g01389016
Terminals at the customer connector that are associated with the engine coolant level sensor
(8) +8 VDC (digital sensor supply)
(9) Return
(36) Engine coolant level
Illustration 7 g01159881
Harness connector for the coolant level sensor
(A) Sensor supply
(B) Sensor return
(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 completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion or of pinch points.Results:
OK - The harnesses 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 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.STOPTest Step 2. Check the Supply Voltage at the Sensor Connector
Disconnect the coolant level sensor at the sensor connector.
Restore electrical power to the ECM.
Measure the voltage between terminals A (sensor supply) and B (sensor return) at the harness connector for the coolant level sensor.
Remove electrical power from the ECM. 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.Repair: The digital sensor supply voltage is not reaching the sensor. There is a problem in the circuit for the digital sensor supply. Refer to Troubleshooting, "Sensor Supply - Test".STOPTest Step 3. Check the Coolant Level