C27 and C32 Engines for Caterpillar Built Machines Caterpillar

Oil Level - Test

Usage:

990K A9P

Use this procedure to troubleshoot any suspect problems with the circuit for the engine oil level sensor.

The Electronic Control Module (ECM) monitors the engine oil level prior to engine starting.

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Illustration 1	g02275313
Components of the oil level sensor (1) Sensor (2) Sensor probe (brass dowel) (3) Plastic cover

Oil 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 a plastic cover (3).

When the sensor probe is immersed in oil, the sensor senses a particular capacitance. The sensor electronics react by sinking the signal to the return (ground). When the probe is not immersed in oil, the supply voltage is sourced to the signal wire.

A problem with the oil level sensor is probably caused by 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 oil level is OK.

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Illustration 2	g02306496
Schematic for the oil level sensor

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Table 1
Troubleshooting Test Steps	Values	Results
1. Inspect the Electrical Connectors and the Wiring A. Remove electrical power from the ECM. B. Thoroughly inspect the connector for sensor. Also, thoroughly inspect ECM connector and all of the connectors in the circuit. 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 oil level sensor.	Electrical Connectors and Wiring	Result: The harnesses and the wiring appear to be OK. Proceed to Test Step 2. Result: 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. If the repair does not eliminate the problem, proceed to Test Step 2.
2. Check the Supply Voltage at the Sensor Connector A. Disconnect the oil level sensor at the sensor connector. B. Restore electrical power to the ECM. C. Measure the voltage between terminals A (supply) and B (return) at the harness connector for the oil level sensor. D. Remove electrical power from the ECM.	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 3. Result: The voltage measurement is not 8.0 ± 0.4 VDC. Repair: The 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". If the repair does not eliminate the problem, proceed to Test Step 2.
3. Short the Signal Wire to Ground and Monitor the Status for "Engine Off Oil Level" A. Remove electrical power from the ECM. B. Fabricate a jumper wire that is long enough to create a short circuit between two terminals at the oil level sensor harness connector. Crimp connector pins to each end of the jumper wire. C. Install the jumper wire between terminals B (return) and C (signal) on the harness side of the connector for the oil level sensor. D. Restore electrical power to the ECM. E. Monitor Cat ET while the jumper wire is installed. Check for the status of the "Engine Off Oil Level" parameter to change as the jumper wire is connected. Note: Wait at least 30 seconds for the status of the parameter to update. F. Remove electrical power from the ECM. G. Remove the jumper wire. Connect the harness connector for the oil level sensor.	"Engine Off Oil Level" Parameter	Result: The parameter changes when the jumper wire is installed. The ECM and the wiring harness to the oil level sensor are OK. Perform the following procedure: 1. Drain the oil below the level of the oil level sensor. 2. Restore electrical power to the ECM. 3. Monitor Cat ET. Check for the "Engine Off Oil Level" to change. Note: Wait at least 30 seconds for the status of the parameter to change. 4. Remove electrical power from the ECM. If the status of the parameter does not change, replace the sensor. If the status of the parameter changes, the circuit for the oil level sensor is OK. There may be an intermittent problem in the harness or in a connector. Check the oil level. Add oil to the engine as necessary. Refer to the Operation and Maintenance Manual. Return the engine to service. If an intermittent electrical problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for troubleshooting information. If the repair does not eliminate the problem, proceed to Test Step 4. Result: Shorting the harness does not change the status parameter. The problem is between the ECM and the harness connector. There may be a problem with the ECM. Proceed to Test Step 4.

4. Check the Wiring Harness for an Open Circuit A. Remove electrical power from the ECM. B. Disconnect the J1/P1 ECM connector and the connector for the oil level sensor. C. Fabricate a jumper wire that is long enough to provide a test circuit between the ECM connector and the sensor connector. Crimp a connector pin to one end of the jumper wire. D. Install the jumper wire connector pin into terminal C on the harness side of the connector for the oil level sensor. E. Measure the resistance between the terminal for the signal of the sensor and the loose end of the jumper wire at the J1/P1 connector . The correct resistance measurement is a short circuit. Remove the jumper wire. Leave the sensor connector disconnected.	Short Circuit	Result: The measurement did not indicate a short circuit. Repair: There is an open circuit or excessive resistance in the harness or the connectors. Repair the wire and/or the connector, when possible. Replace damaged parts, if necessary. If the repair does not eliminate the problem, proceed to Test Step 5.

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Table 2
Resistance Measurements for the Oil Level Circuit
Connector and Terminal	Terminal
P1-7 at the ECM connector	All of the terminals on the P1 connector
	All of the other terminals on the P2 connector
	Engine ground stud

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Table 3
Troubleshooting Test Steps	Values	Results
5. Check the Harness Wiring for a Short Circuit A. Remove electrical power from the ECM. B. Disconnect the J1/P1 ECM connectors. Also, disconnect the connector for the oil level sensor. C. Measure the resistance between the points that are listed in Table 2. Note: Wiggle the harness during the following measurements in order to reveal an intermittent condition.	Open Circuit	Repair: Each check of the resistance indicates an open circuit. There is not a short circuit to another wire in the harness. Proceed to Test Step 6. Result: At least one check of the resistance does not indicate an open circuit. There is a short to another wire in the harness. The problem may be with a connector. Repair: Repair the wire and/or the connector, when possible. Replace damaged parts, if necessary. Verify that the problem is resolved. If the repair does not eliminate the problem, proceed to Test Step 6.
6. Check the Operation of the ECM A. Fabricate a jumper wire that is long enough to provide a test circuit across the ECM connectors. Crimp connector sockets to each end of the jumper wire. B. Use a wire removal tool to remove the wires from terminal locations P1-7 (engine oil level) and P1-5 (return) from the J1/P1 ECM connector. Install the jumper wire into these terminal locations. C. Restore electrical power to the ECM. D. Use Cat ET to monitor the status of the "Engine Off Oil Level" parameter. Use a wire removal tool to remove the jumper wire and check the status again. Note: Wait at least 30 seconds for the status of the parameter to change. E. Remove electrical power from the ECM. Restore all wiring to the original configuration.	"Engine Off Oil Level" Parameter	Result: The status of the "Engine Off Oil Level" parameter changes when the jumper wire is connected. Repair: The ECM is properly reading the switch input. There may be an intermittent problem in the harness or in a connector. If an intermittent electrical problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for troubleshooting information. Verify that the repair eliminated the problem. Result: The status of the "Engine Off Oil Level" parameter did not change when the jumper wire is connected. Repair: The ECM is not reading the switch input. There may be a problem with the ECM. Before you consider replacing the ECM, consult the Dealer Solution Network (DSN) for assistance. Verify that the repair eliminated the problem.