PISTON AS 2835980 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the starting system or if one of the diagnostic codes in Table 1 is active.
Table 1
Diagnostic Codes Table    
Code and Description     Conditions which Generate this Code     System Response    
444-5 Starter Motor Relay current below normal     The Electronic Control Module (ECM) detects an open circuit and/or a short to the +Battery in the start relay.     The code is logged.    
444-6 Starter Motor Relay current above normal     The ECM detects a short circuit to ground in the start relay.    The ECM receives two input signals from the start/run/stop switch. When both of the input signals are high or open, the ECM assumes that the start/run/stop switch is in the STOP position. When both of the input signals are low or shorted to the digital return terminal, the ECM assumes that the start/run/stop switch is in the START position. After the start/run/stop switch is turned to the START position, the ECM will initiate the starting sequence. The ECM will energize the prelube system if the prelube system is available and activated. After the prelube cycle is completed the ECM will energize the start relays.The ECM has the ability to crank the engine when the circuit for the start/run/stop switch is activated. The crank cycle will continue for the time that is equal to the cycle crank time that has been programmed or the crank cycle will continue until the engine speed reaches the crank terminate speed. If crank terminate speed is not reached in the time that is equal to the cycle crank time, the starting motor will deactivate for a time that is equal to the cycle crank time.This process will repeat for a programmed amount of times (Total Number of Crank Cycles). If the engine does not start the starter mode on the Caterpillar Electronic Technician (ET) will display "OVERCRANK". The engine control will be in an idle state.
Illustration 1 g01268846
Typical schematic
Illustration 2 g01268849
P1 ECM connector (P1-5) Digital return (P1-21) Start/Run/Stop input 1 (P1-22) Start/Run/Stop input 2
Illustration 3 g01269000
P2 ECM connector (P2-6) Crank relay
Illustration 4 g01268992
Machine interface connector (Terminal 03) Crank relay (Terminal 09) Digital return (Terminal 37) Start signal
Illustration 5 g01234146
Location of ECM connectorsTest Step 1. Inspect Electrical Connectors and Wiring
Turn the switch that provides power to the keyswitch input for the ECM to the OFF position.
Turn the breaker for the ECM to the OFF position.
Thoroughly inspect the ECM connectors. Inspect all of the other connectors for 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 connector 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 the wiring for abrasion and for pinch points.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion,