3512B and 3512C Petroleum Generator Set Engines Caterpillar

Air Shutoff - Test

Usage:

Use this procedure in order to troubleshoot the air shutoff system. Or, use this procedure if any one of the diagnostic codes in Table 1 is active or easily repeated.

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Table 1
Diagnostic Codes Table
J1939 Code and Description	Conditions which Generate this Code	System Response
2813-5 Engine Air Shutoff Command Status : Current Below Normal	The Electronic Control Module (ECM) detects low current in the circuit. The ECM can only detect this condition when the output driver is not activated.	The code is logged.
2813-6 Engine Air Shutoff Command Status : Current Above Normal	The ECM detects excessive current flow in the circuit. The ECM can only detect this condition when the output driver is activated.	The code is logged.

Note: The air shutoff is optional. Set the programmable parameter to "Installed" with Caterpillar Electronic Technician (ET) in order to enable the air shutoff system. The ECM can detect the air shutoff system on the engine when the configurable parameter is not set to "Installed",

The ECM can stop the engine by shutting off the inlet air supply in an emergency situation. The ECM activates the output driver for the emergency shutdown system. The "ASOS" energizes the two air shutoff solenoids. The solenoids trip the air shutoff valves.

There are two conditions which cause the ECM to activate the output driver for the air shutoff. The first condition occurs when the operator activates the customer emergency stop. The ECM will energize the output driver for the "Air Shutoff" system for one second.

The second condition occurs for an engine overspeed. If an engine overspeed occurs, the ECM will energize the output driver for the "Air Shutoff" system for one second.

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Illustration 1	g03316854
Air shutoff schematic

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Illustration 2	g03320811
P1/J1 ECM connector (P1-55) + battery (P1-56) Air shutoff detect

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Illustration 3	g03320812
P2/J2 ECM connector (P2-13) Air shutoff drive

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Table 2
Troubleshooting Test Steps	Values	Results
1. Inspect the Electrical Connectors and the Wiring A. Turn the main disconnect switch to the OFF position. B. Thoroughly inspect the ECM connectors. Inspect all of the connectors that are associated with the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit. D. Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. E. Check the harness and wiring for abrasion and for pinch points from the sensors back to the ECM.	Connectors	Results: The harness and connectors appear to be OK. Proceed to Test Step 2 Results: There is a problem with the connectors and/or wiring. Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are coupled. Verify that the repair eliminates the problem.
2. Check for Diagnostic Codes that are Active or Logged A. Connect Caterpillar Electronic Technician (ET) to the service tool connector. B. Restore electrical power to the ECM. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. D. Turn the main disconnect switch to the OFF position.	Codes	Result: A 2813-5 or a 2813-6 code is not active or logged. Repair: There does not appear to be an electrical problem at this time. If the problem is intermittent, refer to Troubleshooting, "Electrical Connectors - Inspect". Result: A 2813-5 or a 2813-6 code is active or logged. Proceed to Test Step 3
3. Check the Supply Voltage to the Air Inlet Shutoff Solenoid A. Restore electrical power to the ECM. B. Activate the "Air Inlet Shutoff Relay Output" test on Cat ET. C. Measure the voltage across the two terminals of the air inlet shutoff solenoid. Note: The timer for the air shutoff relay will only power the circuit for 2.5 seconds. The voltage must be checked within this time period. D. Turn the main disconnect switch to the OFF position.	The voltage is within ±5 VDC of battery voltage	Result:The voltage is within ±5 VDC of battery voltage when the test is active. The ECM is properly controlling the relay for the air inlet shutoff solenoid, but the air inlet shutoff solenoid is not working. Repair: Replace the air inlet shutoff solenoid. Verify that the repair eliminates the problem. Results: The voltage is not within ±5 VDC of battery voltage when the test is active. The air inlet shutoff solenoid is not receiving the correct signal. Proceed to Test Step 4
4. Check the Signal Voltage to the Relay A. Restore the electrical power to the ECM. B. Activate the "Air Inlet Shutoff Relay Output" test on Cat ET. C. Measure the voltage across the relay solenoid.	The voltage is within ±5 VDC of battery voltage	Results: The voltage is within ±5 VDC of battery voltage when the test is active. The relay is receiving the signal from the ECM. Proceed to Test Step 5. Result: The voltage is not within ±5 VDC of battery voltage when the test is active. The relay is not receiving the signal from the ECM. Proceed to Test Step 7.
5. Check the Power Supply to the Relay A. Measure the voltage between the +Battery terminal of the relay and the engine ground. G. Turn the main disconnect switch to the OFF position.	The voltage is within ±5 VDC of battery voltage	Results: The voltage is within ±5 VDC of battery voltage. The relay is receiving power. Proceed to Test Step 6. Result: The voltage is not within ±5 VDC of battery voltage. There is a problem in the wiring between the relay and the +Battery terminal. Repair: Repair the circuit. Verify that the repair eliminates the problem.
6. Check the Output Voltage of the Relay A. Ensure that all of the circuits connectors are connected. B. Restore the electrical power to the ECM. C. Activate the "Air Inlet Shutoff Relay Output" test on Cat ET. D. Measure the voltage from the output terminal on the relay to the engine ground.	The voltage is within ±5 VDC of battery voltage	Results: The voltage is within ±5 VDC of battery voltage. There is a problem in the wiring between the relay and the air inlet shutoff solenoid. Repair: Repair the circuit. Verify that the repair eliminates the problem. Results: The voltage is not within ±5 VDC of battery voltage. The relay is not sending power to the air inlet shutoff solenoid. Repair: Replace the relay for the air inlet shutoff. Verify that the repair eliminates the problem.
7. Check for a Short in the Wiring Harness between the Relay and the ECM A. Turn the main disconnect switch to the OFF position. B. Disconnect the J2/P2 and the J1/P1 ECM connectors C. Disconnect the air inlet shutoff relay D. Measure the resistance between terminals P1-19 and P2-14.	Check resistance.	Results: The resistance is an open circuit. Proceed to Test Step 8. Results: The resistance is not an open circuit. There is a problem in the wiring harness between the ECM and the relay. Repair: Repair the circuit. Verify that the repair eliminates the problem.
8. Check for an Open in the Wiring Harness between the Relay and the ECM A. Turn the main disconnect switch to the OFF position. B. Install a jumper wire between terminals 1 and 2 on the connector for the air inlet shutoff relay. C. Measure the resistance between terminals P1-19 and P2-14.	Check resistance.	Results: The resistance is a short circuit. Proceed to Test Step 9. Results:The resistance is not a short circuit. There is a problem in the wiring harness between the ECM and the relay. Repair: Repair the circuit. Verify that the repair eliminates the problem.
9. Check the Relay Signal at the ECM A. Turn the main disconnect switch to the OFF position. B. Remove the terminals from P1-19. C. Restore the electrical power to the ECM. D. Measure the voltage between terminals and -Batt. E. Activate the "Air Inlet Shutoff Relay Output" test on Cat ET. Turn the main disconnect switch to the OFF position. G. Return the wiring to the original configuration.	The voltage is within ±5 VDC of battery voltage	Results: The voltage is within ±5 VDC of battery voltage. The ECM is supplying the correct voltage. There is a problem in the harness between the ECM and the air inlet shutoff relay. Repair: Repair the circuit. Verify that the repair eliminates the problem. Results:The voltage is not within ±5 VDC of battery voltage. The ECM is not supplying the correct voltage. Repair: Replace the ECM. Refer to Troubleshooting, "Test ECM Mode". Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance. Verify that the repair eliminates the problem.