0330523 JOHNSON RETAINING RING, Vacuum switch

Illustration 1 g01150024
Components of the 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 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'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 g01365215
Schematic for coolant level sensor
Table 1
Troubleshooting Test Steps     Values     Results    
1. Verify that the "Coolant Level Sensor" Parameter is Programmed Correctly
A. Remove electrical power from the ECM.
B. Connect the Cat ET to the service tool connector.
C. Restore electrical power to the ECM.
D. Establish communication with the ECM.
E. Verify that the "Coolant Level Sensor" parameter is programmed to "Installed".
F. Remove electrical power from the ECM.    
The "Coolant Level Sensor" parameter is programmed to "Installed".    
Result: The "Coolant Level Sensor" parameter is programmed correctly.
Proceed to Test Step 2.
Result: The "Coolant Level Sensor" parameter is not programmed correctly.
Program the "Coolant Level Sensor" parameter to "Installed".
Verify that the repair eliminates the problem.    
Illustration 3 g01365227
Location of the coolant level sensor (typical left front engine view) (4) Coolant level sensor
Illustration 4 g01365249
Location of the ECM connectors (typical engine view) (5) J2/P2 connectors
Illustration 5 g01365250
Terminal locations at the P2 ECM connector for the coolant level sensor (P2-29) Digital sensor supply (P2-49) Coolant level (P2-92) Sensor return
Illustration 6 g01159881
Terminal locations at the harness connector for the coolant level sensor (Terminal A) Digital sensor supply (Terminal B) Sensor return (Terminal C) Sensor signal
Table 2
Troubleshooting Test Steps     Values     Results    
2. Inspect the Electrical Connectors and the Wiring
A. Remove electrical power from the ECM.
B. Thoroughly inspect the connectors for sensor (4). Also, thoroughly inspect ECM connectors (5). Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Perform a
45 N (10 lb) pull test on each of the wires that are associated with the circuit for the coolant level sensor.
D. Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.    
All connectors, pins, and sockets are coupled completely and/or inserted, and the harness and wiring are free of corrosion, of abrasion or of pinch points.    
Result: The harnesses and the wiring appear to be OK.
Proceed to Test Step 3.
Result: There is a problem with the connectors and/or the wiring.
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 problem is resolved.    
3. Check the Supply Voltage at the Sensor Connector
A. Disconnect the coolant level sensor at the sensor connector.
B. Restore electrical power to the ECM.
C. Measure the voltage between terminals A (digital sensor supply) and B (sensor return) at the harness connector for the coolant level sensor.
D. Remove electrical power from the ECM.    
The voltage measurement is 8.0 0.4 VDC.
   
Result: The voltage measurement is 8.0 0.4 VDC. The supply voltage is reaching the sensor. Proceed to Test Step 4
Result: The voltage measurement is not 8.0 0.4 VDC.
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".    
4. Check the Coolant Level
A. Remove electrical power from the ECM.
B. Allow the engine to cool prior to removal of the cooling system pressure cap.
C. Check the coolant level. Refer to the Operation and Maintenance Manual for the proper procedure to check the coolant level.    
The coolant is at the proper level.
   
Result: The coolant is at the proper level. Proceed to Test Step 5.
Result: The coolant level is low.
Add coolant according to the procedure in the Operation and Maintenance Manual.
There can be a leak in the cooling system. Identify the source of the coolant leak. Repair the leak.    
5. Disconnect the Coolant Level Sensor and Monitor the Status for "Coolant Level"
A. Disconnect the harness con