MAGNET ASSEM. 8D5578 - Caterpillar

Use this procedure to troubleshoot a problem with a solenoid valve. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.
Table 1
J1939 Code and Description Comments
632-7
Engine Fuel Shutoff Valve #1 : Not Responding Properly The code is set when all the following are true:
- In order for the code to be set the engine must first be running
- Engine Control Switch (ECS) is placed in the STOP position and the Engine ECM has de-energized the GSOV output.
- Engine speed greater than "Crank Terminate RPM" has been detected and the "Engine Speed Drop Time" has been exceeded.
The code is logged.
The red stop lamp is illuminated.
The power to the GSOV remains in the de-energized state and the ECM inhibits cranking. The ECM contains the logic and the outputs for control of starting the engine and stopping the engine. Some of the logic for starting the engine and for stopping the engine is customer programmable. The logic responds to inputs from the following components: ECS, emergency stop switch, remote start switch, data link, and other inputs.The ECM outputs a signal to control the solenoid for the GSOV. To enable gas flow to the engine, the GSOV must be energized.The most likely cause of a diagnostic code is a poor electrical connection or a problem in a wiring harness. The next likely cause may be a problem with the solenoid. The least likely cause is a problem with the ECM.When the 632-7 Engine Fuel Shutoff Valve #1 : Not Responding Properly occurs, the ECM assumes that the GSOV did not close. If the GSOV does not respond to the ECM command, unburned gas will remain in the air inlet and exhaust system.Note: Ensure that the unburned gas is purged from the exhaust before restarting the engine. Failure to purge the unburned gas from the engine may result in an explosion in the exhaust piping.
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
In order for the 632-7 code to be set the engine must first be running. The code will be set after a shutdown is commanded.
B. Start the engine and run the engine at low idle.
C. Set the engine control switch to STOP.
D. Determine if a code is active or logged.
Codes
Result: A 632-7 Engine Fuel Shutoff Valve #1 : Not Responding Properly code is active.
Repair: The engine ECM has de-energized the output for the GSOV power supply relay but the engine did not shutdown within the configured"Engine Speed Drop Time".
Check configuration setting to adjust the"Engine Speed Drop Time" if necessary.
The GSOV may be shorted to + Battery or the valve may be stuck open.
Proceed to Test Step 2.
2. Check for a Short Circuit to +Battery in the Harness.
A. Ensure that no gas is present in the surrounding atmosphere.
B. Verify that the engine control is set to STOP.
C. Disconnect the connector from the GSOV.
D. Use a multimeter to check the voltage at the harness connector for the