0393079 JOHNSON CAP & LANYARD

Table 1
Diagnostic Codes Table    
Code    Conditions which Generate this Code    System Response    
1844-5 Fuel Actuator : Current Below Normal     The circuit driver for the electrohydraulic actuator's solenoid is energized. The Electronic Control Module (ECM) detects no current from the actuator or a current that is less than the normal level.     The shutdown output is activated. The code is logged.    
1844-6 Fuel Actuator : Current Above Normal     The circuit driver for the electrohydraulic actuator's solenoid is energized. The ECM detects a current from the actuator that is greater than the normal level.    The ECM controls the fuel actuator by adjusting current flow through the actuator's solenoid.The diagnostic code is probably caused by a short circuit in a harness or by a problem with an electrical connector. The next likely cause is a short circuit inside the actuator solenoid. The least likely cause is a problem with the ECM.Logged diagnostic codes provide a historical record. Before you begin this procedure, use the Caterpillar Electronic Technician (ET) to print the logged codes to a file.This troubleshooting procedure may generate additional diagnostic codes. Keep your mind on correcting the cause of the original diagnostic code. Clear the diagnostic codes after the problem is resolved.
Illustration 1 g01439060
Schematic of the circuit for the fuel actuator on in-line engines and vee enginesTest Step 1. Inspect the Electrical Connectors and WiringNote: This step is important for troubleshooting a problem with instability.
Illustration 2 g01431198
Terminal Box (1) ECM connector J2/P2 (2) ECM connector J1/P1 (3) 16 amp circuit breaker (4) Connectors J3/P3 for the customer's connector (5) Connectors J4/P4 for the optional control panel (if equipped) or for a customer's connector (6) J5/P5 connectors for the harness (7) J6/P6 connectors for the harness
Turn the engine control switch to the OFF position. Switch the 16 amp circuit breaker for the ECM to the OFF position.Note: For the following steps, refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01439063
P2 ECM terminals that are used by the fuel actuator's solenoid on in-line engines and vee engines (P2-6) Fuel actuator's circuit driver (P2-7) Return
Illustration 4 g01809013
Terminal locations at the P6 connector on the terminal box that are used by the fuel actuator's solenoid on in-line engines (P6-55) Return (P6-68) Fuel actuator's circuit driver
Illustration 5 g01439067
Terminal locations at the P5 connector on the terminal box that are used by the fuel actuator's solenoid on vee engines (P5-57) Return (P5-70) Fuel actuator's circuit driver
Illustration 6 g00899691
Fuel actuator (AA) Solenoid's connector (A) Fuel actuator's circuit driver (B) Return
Thoroughly inspect each of the following connectors:
ECM J2/P2 connectors
J5/P5 connectors on the terminal box
J6/P6 connectors on the terminal box
Connectors for the fuel actuator
Check the allen head screw on each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Perform a 45 N (10 lb) pull test on the wires that are associated with the circuit for the fuel actuator.
Thoroughly inspect the connectors for the fuel actuator for moisture and for corrosion. Check the harness and wiring for abrasion and for pinch points from the fuel actuator to the ECM.Expected Result:All connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points.Results:
OK - All connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points. The components are in good condition with proper connections. Proceed to Test Step 2.
Not OK - At least one of the connectors, pins, or sockets is not connected properly. At least one connector or wire has corrosion, abrasion, and/or pinch points. The components are not in good condition and/or at least one connection is improper.Repair: Perform the necessary repairs and/or replace parts, if necessary.STOPTest Step 2. Check for Active Diagnostic Codes
Prevent fuel from entering the engine. Verify that the gas supply to the engine is OFF.
Connect Cat ET to the service tool connector.
Switch the 16 amp circuit breaker for the ECM ON.
If an 1844-5 and/or 1844-6 diagnostic code is logged, clear the code.
Turn the engine control switch to the START position and crank the engine. Allow a minimum of 30 seconds for the generation of any codes.
Observe the "Active Diagnostic" screen on Cat ET. Check and record any active diagnostic codes.
Determine if the problem is related to an open circuit diagnostic code (-5) or a short circuit diagnostic code (-6).
Turn the engine control switch to the STOP position.Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active.Repair: The problem may have been related to a faulty connection in the harness. Carefully inspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - A short circuit diagnostic code (-6) is active at this time. Proceed to Test Step 3.
Not OK - An open circuit diagnostic code (-5) is active at this time. Proceed to Test Step 5.Test Step 3. Disconnect the Connector for the Fuel Actuator's Solenoid in Order to Create an Open Circuit
Prevent fuel from entering the engine. Verify that the gas supply to the engine is OFF.
Turn the engine control switch to the OFF position. Switch the 16