CAP-DUST 3Y4258 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the engine starting system. Also, use this procedure if 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
444-5 Start Relay open circuit The Electronic Control Module (ECM) detects an open circuit and/or a short to the +Battery in the start relay. The ECM can only detect this condition when the start relay is not energized. The code is logged.
444-6 Start Relay short to ground The ECM detects a short circuit to ground in the start relay. The ECM can only detect this condition when the start relay is energized. The ECM can crank the engine when the Engine Control Switch (ECS) is placed in the START position. After the ECS is placed in the START position, the ECM will begin the prelube cycle. When the prelubrication pressure switch opens, the ECM will start the first crank cycle. 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 before the crank cycle time, the starting motor will deactivate at the end of the crank cycle time.This process will repeat for a programmed amount of times (Total Number of Crank Cycles). If the engine does not start, Caterpillar Electronic Technician (ET) will display "OVERCRANK". The engine control will be in an idle state. The process can be restarted by turning the ECS to the OFF position. Next turn the ECS to the STOP position. Then turn the ECS to the START position. The ECM will send a signal to the starting motor relays after the prelube cycle is complete. The starting motor relays will energize closing the normally open contacts of the relays. Current will flow to the starting motors from the "mag relay breaker". The starting motors will begin to crank the engine.The engine can be manually started by using the manual crank switch.
Illustration 1 g03323826There are also configuration parameters that are used to configure the ECM for the type and the location of the starting motors. The following types of starting motors can be used on this engine:
Air starting motor
Electric starting motorThe wiring for each of these types of engine starting circuits is similar. Follow this procedure in order to troubleshoot the circuit diagnostics for any of these types of engine starting system.The ECM can control a secondary starting system that is installed on the engine opposite the primary starting system. Refer to Troubleshooting, "Configuration Parameters" for information that is related to the configuration parameters that are for the secondary starting system.ECM Activation of the Starting MotorsThe ECM utilizes two output drivers in order to crank the engine. Each output driver is provided with 24 VDC during engine cranking. The circuits for the output drivers utilize a return