FRAME AS 1420791 - Caterpillar

Illustration 3 g00850138
Typical air inlet shutoff solenoid
Table 3
Troubleshooting Test Steps Values Results
6. 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"
C. Measure the voltage across the two terminals of the air inlet shutoff solenoid.
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 7.
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 7.
7. Check the Signal Voltage to the Relay
A. Connect Cat ET.
B. Use Cat ET to perform the following test:
- "Air Inlet Shutoff Override"
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 8.
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 10.
8. 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 9.
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 9.
9. 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"
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 10.
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 10.
10. Check the Wiring for an Open Circuit
A. Turn the main disconnect to the OFF position for 2 minutes. The main disconnect must be off for two minutes to allow the DEF pump to purge, to reset the code, and to reset the DCU.
B. Disconnect the air inlet shutoff relay from the wiring harness. Verify that the harness connector is free