Air Shutoff - Test - No Codes
Use this procedure to troubleshoot a problem with the air shutoff system without an active diagnostic code.
Note: The "Air Shutoff" parameter must be set to "Enabled" in order for the Electronic Control Module (ECM) to energize the air shutoff solenoid.
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| Illustration 1 | g06206182 |
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| Troubleshooting Test Steps | Values | Results |
|---|---|---|
1. Activate the Air Shutoff System A. Connect Cat® Electronic Technician (ET) to the service tool connector. B. If the engine will not start, check the air inlet valve to ensure that the valve is not stuck closed. C. Start the engine. Increase the engine speed to 1500 rpm ± 100 rpm. D. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. E. Start the test. F. Wait for the engine to stop. G. Stop the test. |
Air Shutoff |
Result: The air shutoff doors did not close. Proceed to Test Step 2. Result: The engine is shutdown when the "Air Inlet Shutoff Override" or the "Emergency Stop" is activated. The air inlet shutoff is working correctly. Repair: Reset the air inlet shutoff system. If the problem is not resolved, proceed to Test Step 3. |
2. Inspect Electrical Connectors and Wiring A. Turn the main disconnect switch to the OFF position. B. Thoroughly inspect the connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information. C. Perform a D. Check the harness for abrasions and pinch points. |
Connectors and Wiring |
Result: The connectors and wiring appear to be OK Proceed to Test Step 3. Result: There is a problem with the connectors and/or wiring. Repair: Repair or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled. If the problem is not resolved, proceed to Test Step 3. |
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| Illustration 2 | g00850138 |
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Typical air inlet shutoff solenoid | |
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| Troubleshooting Test Steps | Values | Results |
|---|---|---|
3. Check the Supply Voltage to the Air Inlet Shutoff Solenoid A. Connect Cat ET. B. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. C. Measure the voltage across the two terminals of the air inlet shutoff solenoid. Note: The ECM power supply output to the air shutoff relay is ON for 3 seconds then turns off. The power can only be measure at the solenoid during this duration if no override is available in Cat ET. |
±5 VDC of Battery Voltage |
Result: 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. 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. If the problem is not resolved, proceed to Test Step 4. |
4. Check the Signal Voltage to the Relay A. Connect Cat ET. B. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. C. Measure the voltage across the relay coil. |
±5 VDC of Battery Voltage |
Result: The voltage is within ±5 VDC of battery voltage when the test is active. Repair: 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. Repair: The relay is not receiving the signal from the ECM. If the problem is not resolved, proceed to Test Step 7. |
5. Check the Power Supply to the Relay A. Measure the voltage between the following terminals: - +Battery and Engine ground |
±5 VDC of Battery Voltage |
Result: 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 or replace the wiring harness. If the problem is not resolved, proceed to Test Step 6. |
6. Check the Output Voltage of the Relay A. Ensure that all the circuits connectors are connected. B. Connect Cat ET. C. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. D. Measure the voltage between the following terminals: - Relay output terminal and Engine ground |
±5 VDC of Battery Voltage |
Result: 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 or replace the wiring harness. If the problem is not resolved, proceed to Test Step 7. Result: 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. If the problem is not resolved, proceed to Test Step 7. |
7. Check the Wiring for an Open Circuit A. Disconnect the air inlet shutoff relay from the wiring harness. Verify that the harness connector is free of debris, free of corrosion, and securely connected. B. Connect a jumper wire between the terminals of the harness connector for the relay coil. The coil is replaced with a short circuit. C. Connect Cat ET. D. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. |
Short Circuit |
Result: A -5 code became active during the test. The ECM did not detect the jumper wire. An open circuit in the wiring harness has been detected. Repair: Perform the following procedure: 1. Repair or replace the wiring harness. 2. Connect Cat ET. 3. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. If the problem is not resolved, proceed to Test Step 8. Result: A -6 code became active during the test. The ECM detected the jumper wire. A failed relay has been detected. Repair: Perform the following procedure: 1. Replace the air inlet shutoff relay. 2. Connect Cat ET. 3. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. If the problem is not resolved, proceed to Test Step 8. |
8. Check the Wiring for a Short Circuit A. Disconnect the air inlet shutoff relay from the wiring harness. Verify that the harness connector is free of debris, free of corrosion, and securely connected. B. Connect Cat ET. C. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. |
Open Circuit |
Result: A -6 code became active during the test. The ECM did not detect the open circuit. A short circuit in the wiring harness has been detected. Repair: Perform the following procedure: 1. Repair or replace the wiring harness. 2. Connect Cat ET. 3. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. If the problem is not resolved, proceed to Test Step 9. Result: A -5 code became active during the test. The ECM detected the open circuit. A failed relay has been detected. Repair: Perform the following procedure: 1. Replace the air inlet shutoff relay. 2. Connect Cat ET. 3. Use Cat ET to perform the following test: - "Air Inlet Shutoff Override" Note: If the Cat ET override is unavailable, use the "Emergency Stop Switch" to active the air shutoff system. If the problem is not resolved, proceed to Test Step 9. |
9. Check for Incorrect Configuration Parameters A. Connect to Cat ET. B. Use Cat ET to verify that the correct parameters are being used. -"Inlet Air Shutoff Valve" |
Parameters |
Result: The feature is "Disabled" and a switch is installed. Repair: Input the "Inlet Air Shutoff Valve" parameters "Enabled". Refer to Troubleshooting, "Configuration Parameters" for additional information. Verify that the repair eliminated the problem. Result: The feature is "Disabled" and a switch is not installed. Repair: There is a short in the wiring harness. Repair or replace the wiring harness. Verify that the repair eliminated the problem. |
If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).
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