C3.4B Engines Caterpillar

Switch Circuits - Test - Engine Oil Pressure Switch

Usage:

CCS7 4B2

Use this procedure to diagnose electronic faults in the oil pressure switch circuit.

This procedure covers the following diagnostic code:

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Table 1
Diagnostic Trouble Codes for the Oil Pressure Switch
J1939 Code	Description	Notes
100-2	Engine Oil Pressure : Erratic, Intermittent, or Incorrect	When the keyswitch is in the ON position (engine not running), the oil pressure switch circuit should be closed. This diagnostic code will be active when the Electronic Control Module (ECM) detects the following conditions: The engine is not running. The circuit for the oil pressure switch is open for at least 3 seconds. The keyswitch has been switched on for at least 6 seconds. The battery voltage is at least 10 VDC. The warning lamp will come on.

The engine is equipped with an oil pressure switch. While the engine is running and oil pressure is detected, the switch will be open. When no oil pressure is detected, the switch will be closed.

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Table 2
Oil Pressure Switch States and Diagnostics Summary
Engine Condition	Oil Pressure Switch State	Active Diagnostic Code
Not running	Closed	Normal condition (no oil pressure detected)
Running	Open	Normal condition (oil pressure detected)
Not running	Open	100-2
Running	Closed	100-17

Note: If a 100-17 diagnostic code is active, refer to Troubleshooting, "Oil Pressure Is Low" before returning to this procedure.

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Illustration 1	g03733752
Schematic diagram for the oil pressure switch circuit

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Illustration 2	g02710300
View of the pin location on the 62-pin engine interface connector for the oil pressure switch. (3) Oil pressure switch

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Illustration 3	g02710319
View of the pin location on the P2 connector for the oil pressure switch (6) Engine oil pressure switch

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Table 3
Troubleshooting Test Steps	Values	Results
1. Inspect Electrical Connectors and Wiring A. Thoroughly inspect the terminal connections on the P2/J2 connector. B. Thoroughly inspect the connector for the oil pressure switch. C. Refer to Troubleshooting, "Electrical Connectors - Inspect". D. Perform a 30 N (6.7 lb) pull test on each of the wires in the connectors that are associated with the oil pressure switch. E. Check the harness for abrasions and for pinch points from the oil pressure switch back to the ECM.	Damaged wire or connector	Result: A damaged wire or damaged connector was found. Repair: Repair the damaged wire or the damaged connector. Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault. Result: All connectors, pins, and sockets are correctly connected and/or inserted and the harness is free of corrosion, of abrasion or of pinch points. Proceed to Test Step 2.
2. Check for Active or Recently Logged Diagnostic Codes A. Turn the keyswitch to the OFF position. B. Connect the electronic service tool to the diagnostic connector. C. Turn the keyswitch to the ON position. Do not start the engine. D. Check for any active or recently logged diagnostic codes. Wait at least 10 seconds for activation of the diagnostic codes.	Diagnostic codes	Result: A 100-17 diagnostic code is recently logged. This diagnostic code indicates that the oil pressure is low, but can also be caused by a short circuit condition in the oil pressure switch circuit. Repair: Check for engine oil pressure problems before returning to this procedure. refer to Troubleshooting, "Oil Pressure Is Low". If the fault is still present, proceed to Test Step 3. Result: A 100-2 diagnostic code is active. Proceed to Test Step 6. Result: A 100-2 diagnostic code is not active. A 100-17 diagnostic code is not recently logged. An intermittent 100-2 diagnostic code can be caused by turning the keyswitch to the ON position after the engine has recently been stopped or an intermittent fault may exist. Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" in order to identify intermittent faults.
3. Create an Open Circuit at the Switch Connector A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector for the oil pressure switch. C. Turn the keyswitch to the ON position. Do not start the engine. D. Use the electronic service tool to check for an active 100-2 diagnostic code. Wait at least 10 seconds for activation of the diagnostic code.	Diagnostic codes	Result: A 100-2 diagnostic code is active with the switch disconnected. Repair: Replace the oil pressure switch. Refer to Disassembly and Assembly, "Engine Oil Pressure Switch - Remove and Install". Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 100-2 diagnostic code is not active with the oil pressure switch disconnected. Reconnect the harness connector for the oil pressure switch and proceed to Test Step 4.
4. Create an Open Circuit at the 62-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 62-pin engine interface connector. C. Turn the keyswitch to the ON position. Do not start the engine. Wait at least 30 seconds for activation of the diagnostic codes. D. Use the electronic service tool to check for an active 100-2 diagnostic code. Note: Diagnostic codes for all of the engine sensors will be active with the 62-pin connector disconnected. Ignore all other codes and only look for a 100-2 diagnostic code. E. Turn the keyswitch to the OFF position.	Diagnostic codes	Result: A 100-2 diagnostic code is active with the 62-pin connector disconnected. The fault is in the wiring between the 62-pin connector and the oil pressure switch. Repair: Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 100-2 diagnostic code is not active with the wire disconnected. Reconnect the wire that was previously removed. Proceed to Test Step 5.
5. Create an Open Circuit at the ECM Connector A. Disconnect the P2 connector from the ECM. B. Turn the keyswitch to the ON position. Do not attempt to start the engine. Wait at least 30 seconds for activation of the diagnostic codes. C. Use the electronic service tool to check for an active 100-2 diagnostic code. Note: Diagnostic codes for all of the engine sensors will be active with the P2 connector disconnected. Ignore all other codes and only look for a 100-2 diagnostic code. D. Turn the keyswitch to the OFF position.	Diagnostic codes	Result: A 100-2 diagnostic code is active with the P2 connector disconnected. The fault is in the wiring between the 62-pin connector and the P2 connector. Repair: Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 100-2 diagnostic code is not active with the wire disconnected. Contact the Dealer Solution Network (DSN).
6. Create a Short at the Switch Connector A. Turn the keyswitch to the OFF position. B. Disconnect the harness connector for the oil pressure switch. C. Fabricate a jumper wire and install the jumper wire between the harness connector for the oil pressure switch and a suitable ground. D. Turn the keyswitch to the ON position. Do not start the engine. E. Use the electronic service tool to check for an active 100-2 diagnostic code. Wait at least 10 seconds for activation of the diagnostic code. F. Turn the keyswitch to the OFF position. G. Remove the jumper wire.	Diagnostic codes	Result: A 100-2 diagnostic code is not active with the jumper installed. Repair: Replace the oil pressure switch. Refer to Disassembly and Assembly, "Engine Oil Pressure Switch - Remove and Install". Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 100-2 diagnostic code is active with the jumper installed. Proceed to Test Step 7.
7. Create a Short at the 62-Pin Connector A. Turn the keyswitch to the OFF position. B. Disconnect the 62-pin engine interface connector. C. Fabricate a jumper wire and install the jumper wire between terminal 3 on the 62-pin connector on the harness between the engine and the ECM and a suitable ground. D. Turn the keyswitch to the ON position. Do not attempt to start the engine. Wait at least 30 seconds for activation of the diagnostic codes. E. Use the electronic service tool to check for an active 100-2 diagnostic code. Note: Diagnostic codes for all of the engine sensors will be active with the 62-pin connector disconnected. Ignore all other codes and only look for a 100-2 diagnostic code.	Diagnostic codes	Result: A 100-2 diagnostic code is not active with the jumper installed. The short is in the wiring between pin 3 on the 62-pin connector and the harness connector for the oil pressure switch. Repair: Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 100-2 diagnostic code is active with the jumper installed. Reconnect the 62-pin connector. Proceed to Test Step 8.
8. Create a Short at the ECM Connector A. Turn the keyswitch to the OFF position. B. Disconnect the P2 connector from the ECM. C. Fabricate a jumper wire and install the jumper wire between J2:6 and a suitable ground. D. Turn the keyswitch to the ON position. Do not attempt to start the engine. Wait at least 30 seconds for activation of the diagnostic codes. E. Use the electronic service tool to check for an active 100-2 diagnostic code. Note: Diagnostic codes for all of the engine sensors will be active with the P2 connector disconnected. Ignore all other codes and only look for a 100-2 diagnostic code. F. Turn the keyswitch to the OFF position. G. Remove the jumper wire.	Diagnostic Codes	Result: A 100-2 diagnostic code is not active with the jumper installed. The fault is in the wiring between the oil pressure switch and the P2 ECM connector. Repair: Replace the faulty wiring. Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault. Result: A 100-2 diagnostic code is active with the jumper installed. Contact the DSN.