HUB AS 2923172 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the circuit for the Gas Shutoff Valve (GSOV). Also, use this procedure if one of the following diagnostic codes is active or easily repeated.
Table 1
Diagnostic Codes Table
Description Conditions which Generate this Code System Response
632-5
Engine Fuel Shutoff Valve #1 : Current Below Normal The Electronic Control Module (ECM) detects a low current in the circuit for the GSOV for 2 seconds.
The output driver must be off for 5 seconds in order for this code to become active. The code is logged.
The amber warning lamp is illuminated.
The service tool displays "Error Indicator" on the status screen for this parameter.
632-6
Engine Fuel Shutoff Valve #1 : Current Above Normal While the output driver is on for 5 seconds, the ECM detected a high current in the circuit for the GSOV for one second. The code is logged.
The amber warning lamp is illuminated.
The service tool displays "Error Indicator" on the status screen for this parameter.
The output driver automatically resets and the output driver continues to try to activate the circuit component.
632-7
Engine Fuel Shutoff Valve #1 : Not Responding Properly The Engine Control Switch (ECS) is placed in the STOP position. The ECM has shut off fuel, but the pressure sensor before the fuel valve still reads pressure. 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 in order 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 : Failure 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.The following information describes the systems operation when the GSOV is controlled by the ECM:The ECM controls the solenoid for the GSOV. This output is energize-to-run. When gas blending turns on, the ECM opens the GSOV. When gas blending turns off, the ECM closes the GSOV.
Illustration 1 g03323629
Schematic of the circuit for the GSOV
Illustration 2 g03324932
Location of the connectors at the ECM
(1) J1/P1 ECM