WEIGHT-GOVERNOR 7N7264 - Caterpillar

System Operation Description:Use this procedure in order to troubleshoot the air shutoff system or use this procedure if any one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
446-5 Air Shutdown Relay : Current Below Normal The Electronic Control Module (ECM) detects low current in the circuit. The ECM can only detect this condition when the output driver is not activated. The code is logged.
446-6 Air Shutoff Relay short The ECM detects excessive current flow in the circuit. The ECM can only detect this condition when the output driver is activated.
E2087(3) Air Intake Shutoff Closed The ECM detects an "Active" condition in the detection circuit that monitors the state of the air shutoff valves. The configurable parameter for the air shutoff system is set to "Installed". The code is latched until power is cycled to the ECM. The process for starting the engine will be stopped and the process for starting the engine will be disabled. If engine rpm is present, the air shutoff relay will be activated.
The code is logged.
E2088(1) Air Intake Shutoff Detection Circuit Detected but Not Installed The ECM detects an "Active" condition in the detection circuit that monitors the state of the air shutoff valves. The configurable parameter for the air shutoff system is set to "Not Installed". The code is logged. Note: The air shutoff is optional. A programmable parameter needs to be set to "Installed" with Caterpillar Electronic Technician (ET) in order to enable the air shutoff system. If the air shutoff system is installed on the engine but the configurable parameter is not set to "Installed", the ECM will detect the air shutoff system through the normally closed switches on the air shutoff valves. If this happens the E2088(1) event code will be generated.The ECM has the ability to stop the engine by shutting off the inlet air supply in an emergency situation. The ECM activates the output driver for the emergency shutdown system. The "ASOS" energizes the two air shutoff solenoids. The solenoids trip the air shutoff valves.There are two conditions which cause the ECM to activate the output driver for the air shutoff. The first condition occurs when the operator activates the customer's emergency stop. When the customer's emergency stop button is activated, the emergency stop inputs U and T to the ECM from the customer connector go high. The ECM will recognize this change. The ECM will energize the output driver for the "Air Shutoff" system for one second.The second condition occurs for an engine overspeed. If an engine overspeed occurs, the ECM will energize the output driver for the "Air Shutoff" system for one second. Voltage is applied to relay "R4A" for one second. "R4A" normally open contacts are closed sending voltage to the coil of relay "ASOS" and terminal 2 on "DIODE_1_2" .Voltage from terminal 3 of "DIODE_1_2" is applied to relay "R3A" and relay "R3" at the same time as