0330912 JOHNSON COVER, Air silencer

Illustration 1 g01150024
Components of the 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 probe is immersed in coolant, the sensor senses a particular capacitance. The sensor electronics react by sinking the signal to the sensor 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 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.Before you perform this test procedure, ensure that the coolant level is OK.
Illustration 2 g02688557
Typical schematic for the coolant level sensor
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
Turn the main disconnect switch to the OFF position.
Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g02721290
Location of the J1/P1 and the J2/P2 ECM connectors (typical engine view)
(1) J1/P1 ECM connector
(2) J2/P2 ECM connector
Illustration 4 g02725354
Terminal locations at the P2 ECM connector for the coolant level sensor
(P2-92) Digital return
(P2-29) Digital supply
Illustration 5 g01443908
Terminal locations at the P1 ECM connector for the coolant level sensor
(P1-44) Coolant level
Illustration 6 g01159881
Terminal locations at the harness connector for the coolant level sensor
(Terminal A) Digital supply
(Terminal B) Digital 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 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 (digital supply) and B (digital return) at the harness connector for the coolant level sensor.
Turn the main disconnect switch 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.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. Disconnect the Coolant Level Sensor and Monitor the Status for "Coolant Level"
Disconnect the harness connector for the coolant level sensor.
Restore electrical power to the ECM.
Monitor the status of "Coolant Level" on Cat ET. Note: Wait at least 30 seconds for activation of the status indicator.
Turn the main disconnect switch 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. There may be a problem with the coolant level sensor. Proceed to Test Step 4.
Not OK - The status is "OK" when the sensor is disconnected. The problem is between the ECM and the harness connector. There may be a problem with the ECM. Proceed to Test Step 5.Test Step 4. Short the Signal Wire to Ground and Monitor the Status for "Coolant Level"
Turn the main disconnect switch to the OFF position.
Fabricate a jumper wire that is long enough to create a short circuit between two terminals at the coolant level sensor harness connector. Crimp connector pins to each end of the jumper wire.
Install the jumper wire between terminals B (digital return) and C (sensor signal) on the harness side of the connector for the coolant level sensor.
Restore electrical power to the ECM.
Monitor the status of "Coolant Level" on Cat ET while the jumper wire is installed. Note: Wait at least 30 seconds for activation of the status indicator.
Turn the main disconnect switch to the