PLATE 1265143 - 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 in order to warn the operator when the coolant level is low.
Illustration 1 g01150024
Components of the coolant level sensor
(1) Sensor
(2) Sensor probe (brass dowel)
(3) Outer coatingWhen the probe is not immersed in coolant, approximately 8 VDC is sourced to the sensor 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.
Illustration 2 g02944238Complete the procedure in the order in which the steps are listed.
Table 1
Troubleshooting Test Steps Values Results
1. Check the Coolant Level
Allow the engine to cool prior to removal of the cooling system pressure cap.
A. Remove electrical power from the ECM.
B. Check the coolant level. Refer to the Operation and Maintenance Manual for the proper procedure to check the coolant level.
Coolant Level
Result: The coolant is at the proper level.
Proceed to Test Step 2.
Result: 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. Refer to Systems Operation/Testing and Adjusting, "Cooling System" for additional information.
2. Verify that the "Coolant Level Sensor" Parameter is Programmed Correctly
A. Connect Cat ET to the service tool connector.
B. Establish communication with the ECM.
C. Verify that the "Coolant Level Sensor" parameter is programmed to "Installed".
D. Remove electrical power from the ECM.
Parameter Programmed
Result: The "Coolant Level Sensor" parameter is programmed correctly.
Proceed to Test Step 3.
Result: 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.
Illustration 3 g02090761
Terminal locations at the harness connector for the coolant level sensor
(Terminal A) Sensor supply
(Terminal B) Sensor return
(Terminal C) Sensor signal
Table 2
Troubleshooting Test Steps Values Results
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 (sensor supply) and B (sensor return) at the harness connector for the coolant level sensor.
D. Remove electrical power from the ECM.
8.0 0.5 VDC
Result: The voltage measurement is 8.0 0.5 VDC.
The supply voltage is reaching the sensor. Proceed to Test Step 4.
Result: The voltage measurement is not 8.0 0.5 VDC.
Repair: The sensor supply voltage is not reaching the sensor. There is a problem in the circuit for the sensor supply. Repair the wiring between the sensor and the ECM.
4. Short the Signal Wire to Ground and Monitor the