91302-ZW1-000 Honda O-RING, PUMP COVER (Honda Code 4901278).

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 Electronic Control Module (ECM), an event code is activated. Prior to troubleshooting any problems with the coolant level sensor, use Cat 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.
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.
Table 1
Troubleshooting Test Steps Values Results
1. Check the Coolant Level
A. Remove electrical power from the ECM.
Note: Allow the engine to cool prior to removal of the cooling system pressure cap.
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.
1. Add coolant according to the procedure in the Operation and Maintenance Manual.
2. There may be a leak in the cooling system.
3. Identify the source of the coolant leak.
4. Repair the leak.
2. Verify that the Parameter for the appropriate “Coolant Level Sensor” 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 parameter for the suspect “Coolant Level Sensor” is programmed to “Installed”.
Coolant Level Sensor
Result: The “Coolant Level Sensor” parameter is programmed correctly.
Proceed to Test Step 3.
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 2 g01375504
Top front engine view with a heat exchanger
(4) Engine coolant level sensor
Illustration 3 g01375530
Top front engine view with an expansion tank.
(4) Engine coolant level sensor
(5) Coolant level sensor for the aftercooler
Illustration 4 g01375378
Location of the ECM connectors (rear engine view)
(6) J2/P2 connectors
Illustration 5 g01365250
Terminal locations for the P2 ECM connector
(P2-29) Sensor supply
(P2-49) Coolant level
(P2-92) Sensor return
Illustration 6 g01159881
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. 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 (10lb)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.
Electrical Connectors
Result: The harnesses and the wiring appear to be OK.
Proceed to Test Step 4.
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.
4. Check the Supply Voltage at the Sensor Connector
A. Disconnect the suspect 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 (digital return) at the harness connec