VALVE AS-PRESSURE 5407040 - Caterpillar

Table 6
Troubleshooting Test Step    Values    Results    
5. Problem in the Circuit from the ECM to the Air Shutoff Switch.    
The voltage is not 24 3 VDC    
Results: The voltage is not 24 3 VDC.
Repair: Perform the following procedure:
1. Check the condition of the diodes that are in the diode assembly. Ensure that the diodes are within specifications. Verify that the diodes are not short or open. Replace the diode assembly, if necessary.
2. If the diodes are OK, isolate each segment of the harness and check for 24 3 VDC.
Note: During the measurements, ensure that the battery disconnect switch is in the ON position. Ensure that the emergency stop switch is activated. Also, be sure to use the −Battery as a return for your measurements.
Place the emergency stop switch in the RUN position.
Turn the battery disconnect switch to the OFF position.
Restore the wiring to the original configuration.
If voltage is 24 3 VDC at the diode assembly connector, and the diode assembly is OK, there is a problem in the harness. Check the harness between the connector at the diode assembly and the air shutoff solenoid. Repair the harness or replace the harness. Verify