PLATE 1539121 - Caterpillar

System Operation Description:Use this procedure to troubleshoot suspect problems with the circuit for the starting system.This procedure covers the following diagnostic codes:
444-5 Starter Motor Relay : Current Below Normal
444-6 Starter Motor Relay : Current Above NormalThe master Electronic Control Module (ECM) contains the logic and the outputs for starting the engine. The logic for starting is customer programmable. The logic responds to inputs from the following components: engine control switch, emergency stop switch, remote start switch, data link and other inputs.Logged diagnostic codes provide a historical record. Before you begin this procedure, use Caterpillar Electronic Technician (ET) to print the logged codes to a file.The most likely causes of the diagnostic code are a poor electrical connection or a problem in a wiring harness. The next likely cause is a problem with a magnetic switch or with a relay. The least likely cause is a problem with the master ECM.The 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.Electric StartThe master ECM supplies +Battery voltage to two magnetic switches when the logic determines that it is necessary. Each magnetic switch provides +Battery voltage to a solenoid on an electric starting motor. The master ECM removes the voltage when the crank terminate relay is energized. The voltage is also removed if the customer programmable "Overcrank Time" has expired.Air StartThe master ECM supplies +Battery voltage to the air start relay when the logic determines that it is necessary. The master ECM removes the voltage when the crank terminate relay is energized. The voltage is also removed if the customer programmable "Overcrank Time" has expired.
Illustration 1 g01548874
Schematic for the electric starting system
Illustration 2 g01114229
Schematic for the air start systemTest Step 1. Inspect the Electrical Connectors and Wiring
Remove the electrical power from the engine.Note: For the following steps, refer to Troubleshooting, "Electrical Connectors - Inspect".
Thoroughly inspect the following connectors and the wiring harnesses for the connectors:
J2/P2 connectors
J7/P7 connectors
Check the torque of the allen head screw for the ECM connectors.
Illustration 3 g01055043
Harness side of the P2 connector (P2-10) Start command (P2-20) Return for the start command
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the starting motor relay.
Check the harness and wiring for abrasion and for pinch points from the starter motor relay to the master 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 - The components are in good condition with proper connections. Proceed to Test Step 2.
Not OK - The components are not in good condition and/or at least one connection is improper.Repair: Perform the necessary repairs, when possible. Replace parts, if necessary.STOPTest Step 2. Check for Diagnostic Codes
Connect Cat ET to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Switch the 35 amp circuit breaker ON. Set the engine control to the STOP mode.Note: The 444-5 diagnostic code