SEAL-O-RING 5P8068 - Caterpillar

Use this procedure to troubleshoot any suspect problems with the circuit for the coolant level sensor.The coolant level sensor monitors the engine coolant level to warn the operator if the coolant level is low. The coolant level sensor is on the expansion tank.
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 depends 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 g06112403
Location of the coolant level sensor (typical front engine view)
(4) Coolant level sensor
Illustration 4 g06122070
Location of the coolant level sensor (typical left engine view)
(4) Coolant level sensor
Illustration 5 g01365249
Location of the ECM connectors (typical engine view)
(5) J2/P2 connectors
Illustration 6 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 7 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