HOLDER ASSEM 5S4863 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the air shutoff system. Also, use this procedure if any one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
CDL Code and Description Conditions which Generate this Code System Response
337-2
Remote Emergency Stop Switch : Erratic, Intermittent, or Incorrect The two inputs from the emergency stop switch are in the opposite state. The code is logged.
446-5
Air Shutdown Relay : Current Below Normal The Electronic Control Module (ECM) detects an open circuit and/or a short to the +Battery in the solenoid circuit. The code is logged.
446-6
Air Shutoff Relay short The ECM detects a short circuit to ground in the solenoid circuit. The ECM will stop the engine in an emergency situation by shutting off the air supply to the engine. The ECM energizes the circuit for the air shutoff solenoid. The solenoid supplies air pressure that trips the air shutoff valves for both sides of the engine. The air shutoff solenoid is located on the air shutoff mechanism that is for the right side of the engine.This system also incorporates two switches that monitor the position of the air shutoff mechanisms. If the air shutoff mechanisms are closed, the switches complete a circuit that is wired to a low side ECM driver. The ECM detects this condition and the ECM logs an event code.The air shutoff system is optional for this application. Use Cat® Electronic Technician (ET) to program Air Intake Shutoff Detection Installation Status to "Installed" in order to enable the air shutoff system.There are two conditions which can cause the ECM to activate the air shutoff:Engine Overspeed - The first condition occurs when the ECM detects an engine overspeed. During an engine overspeed, the ECM energizes the circuit for the air shutoff solenoid. An event code is generated for this condition. Once an event for the air shutoff system is activated, the event is latched until electrical power to the ECM system is cycled.Emergency Stop Sequence - The second condition occurs when one of the emergency stop switch is activated. When an emergency stop switch is placed in the STOP position, voltage is supplied directly to the air shutoff solenoid. The solenoid energizes and the air shutoff mechanisms are closed.Ensure that both of the air shutoff mechanisms are manually reset after activating the air shutoff system in order to start the engine again. The main power to the ECM must be turned OFF for 30 seconds to reset the engine control.Use Cat ET to view the "Air Intake Shutoff Position" parameter in order to confirm the status of the air shutoff system.
Illustration 1 g06334901
Schematic for the air shutoff system
Illustration 2 g02616804
Location of the connectors at the control box that are for the fuel control (typical top front engine view)
(1) Right rail connector
(2) J2/P2 ECM connector
(3) J1/P1 ECM connector
(4) Left rail connector
(5) Connector for the primary power harness
(6) Engine interface connector
Illustration 3 g03676012
Location of the components at the air shutoff mechanism (right side engine