RING-BACKUP 1793047 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the air shutoff system or if any one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table    
Description     Conditions which Generate this Code     System Response    
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 has the ability to stop the engine by shutting off the inlet air supply in an emergency situation. The ECM activates the air shutoff solenoid. The air shutoff solenoid closes the air shutoff valve. There are two conditions which cause the engine control to activate the air shutoff solenoid.The first condition occurs when the operator initiates an emergency shutdown. When the "Emergency Kill Relay (EKR)" in the main junction box is energized, a set of normally closed contacts from the "EKR" opens allowing the two emergency shutdown signals to the ECM to go high. When the shutdown is recognized by the ECM the ECM disables fuel injection. The ECM also activates the output driver for the air shutoff solenoid.The second condition is for an engine overspeed. If an engine overspeed occurs, the ECM disables fuel injection. The ECM also activates the output driver for the air shutoff solenoid.Regardless of the reason for activation, the main power to the ECM must be turned OFF for 15 seconds in order to reset the engine control.Note: Ensure that the air shutoff valves are manually reset after an emergency stop in order to start the engine again.Note: The air shutoff is optional. A programmable parameter needs to be set with Caterpillar Electronic Technician (ET) in order to enable the air shutoff.
Illustration 1 g01285745
Typical example
Illustration 2 g01285746
P1 ECM connector (P1-5) Digital return (P1-23) Emergency stop signal C (P1-28) Emergency stop signal D
Illustration 3 g01285748
P2 ECM connector (P2-13) Air shutoff
Illustration 4 g01285750
Location of ECM connectorsTest Step 1. Inspect Electrical Connectors and Wiring
Turn the "main disconnect switch (MDS)" to the OFF position.
Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit.Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
Check the harness and wiring for abrasion and for pinch points from the sensors back to the ECM.Expected Result:All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem