NUT 7K2017 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the air shutoff system. 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 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 can stop the engine by shutting off the air supply in an emergency situation. The ECM activates the air shutoff solenoid which activates the air inlet shutoff valve.The first condition occurs when the operator initiates an emergency shutdown. When the shutdown is recognized, fuel is shut off and the air shutoff solenoid is activated. The second condition is for an engine overspeed.Regardless of the reason for activation, the main power to the ECM must be turned OFF for 3 seconds in order to reset.Note: The air shutoff is optional. A programmable parameter must be set with Caterpillar Electronic Technician (ET) in order to enable the air shutoff.The switch at the air shutoff valve allows the ECM to determine if the air shutoff valve is open or closed. If the shutoff valve is closed, the switch is in the closed position and the ECM will not start the engine. Open the air shutoff valve in order to start the engine. The customer can activate the air shutoff solenoid by supplying 24 VDC to terminal 04 of the customer connector.Note: Ensure that the air shutoffs are manually reset after an emergency stop in order to start the engine again.
Illustration 1 g03775212
Typical schematic
The prefix R1A has a single air shutoff switch that is not shown on the schematic above.
The prefix R1S has a left side and right side air shutoff switch in series as shown above.
Note: The J1-56 (ECM) pin needs 24VDC to let the (ECM) know that the air shutoff valves are in the open position. When the 24VDC is interrupted on pin J1-56 then the door closes.
Illustration 2 g01212647
P1 ECM connector
(P1-5) Digital return
(P1-21) Start/Run/Stop input 1
(P1-22) Start/Run/Stop input 2
(P1-23) Emergency stop signal "C"
(P1-28) Emergency stop signal "D"
(P1-52) +Battery
(P1-53) +Battery
(P1-55) +Battery (ECM)
(P1-56) Air shutoff (NO)
(P1-63) −Battery
(P1-65) −Battery
(P1-70) Keyswitch
Illustration 3 g01212649
P2 ECM connector
(P2-13) Air shutoff
Illustration 4 g01234146
Location of ECM connectors
Illustration 5 g01212650
Customer connector
(Terminal 01) +Battery
(Terminal 02) +Battery
(Terminal 04) Air shutoff
(Terminal 09) Digital return
(Terminal 16) Emergency stop signal "D"
(Terminal 17) Emergency stop signal "C"
(Terminal 23) Start/Run/Stop input 1
(Terminal 24) Start/Run/Stop input 2
(Terminal 27) Keyswitch
(Terminal 34) −Battery
(Terminal 35) −Battery Test Step 1. Inspect Electrical Connectors and Wiring
Remove power from the ECM.
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