3512C and 3516C Marine Auxiliary Engines 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
J1939 Code and Description	Conditions which Generate this Code	System Response
677-5 Engine Starter Motor Relay : Current Below Normal	The engine Electronic Control Module (ECM) detects an open in the circuit for the starter relay. The ECM detects a short to battery voltage in the circuit for the starter relay. The ECM can only detect this condition when the output driver is not activated.	The code is logged.
677-6 Engine Starter Motor Relay : Current Above Normal	The ECM detects a short in the circuit for the starter relay. The ECM can only detect this condition when the output driver is activated.

Use this procedure to troubleshoot the electrical system if a problem is suspected with the starting system.

The ECM is provided with the ability to begin the engine cranking at any time after the ECM has received keyswitch power. The ECM receives the start command via the global CAN data link. Once this request is received, the engine is placed into the "Prestart State" of the control for the engine state. If the engine is equipped with a prelubrication system, the engine will wait until the prelube cycle has been completed before initiating engine cranking.

Configuration Parameters

The settings of the following configuration parameters control engine starting:

• Starting System #1 Maximum Number of Crank Cycles

• Starting System #1 Crank Duration

• Crank Terminate RPM

Configuration parameters for Starting System #2 are also available. Refer to Troubleshooting, "Configuration Parameters" for information that is related to these parameters.

Illustration 1	g02987576
Schematic for the engine starting system

There 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 motor

The 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 Motors

The 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 line to the ECM. This circuit includes crank relays that can be powered by an external power supply in order to override the ECM activation of the starting motors.

Manual Overrides for the Engine Starting System

The engine can be manually cranked by using a manual crank switch that can be wired into the engine interface connector. The engine starting circuit incorporates four crank relays. When the relay coils are powered by 24 VDC, the starting motor magnetic switches are fused at the low current power distribution panel. The switch and the wiring for the circuit must be supplied by the customer.

Caterpillar Electronic Technician (ET) can be used in order to override the output command that is provided by the engine state control. This override can be used to diagnose the circuit that is for the starting motor magnetic switches. View the "Starting System Relay Status" that is available in Cat ET in order to determine the status of the ECM outputs.

Illustration 2	g02706411
Terminal locations at the P2 ECM connector (prim. & sec.) for the engine starting system (P2-60) Right starter enable − (prim. & sec.) (P2-59) Right starter enable + (prim. & sec.) (P2-51) Left starter enable + (prim. & sec.) (P2-43) Left starter enable − (prim. & sec.)

Illustration 3	g01533453
Terminal locations at the keyswitch relay and the relay for the power mode circuit (Terminal 1) Power to the starting motor magnetic switch (Terminal 2) Power from the override switch that is used to override the ECM signal (Terminal 3) Signal line or return line from the ECM (Terminal 4) Power or return for the secondary circuit of the relay that is for the manual override (Terminal 5) Return for the control circuit of the relay

Illustration 4	g01155187
Terminal locations at the connector for the starting motor magnetic switch (Terminal 1) Relay signal circuit to the pump (Terminal 2) Return

Table 2

Troubleshooting Test Steps	Values	Results
1. Inspect the Electrical Connectors and the Wiring A. Turn the main disconnect switch to the OFF position. B. Thoroughly inspect the connectors that are associated with the starting system. Ensure that a circuit breaker has not tripped. Refer to Troubleshooting, "Electrical Connectors - Inspect " for details. C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit. D. Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect " for the correct torque values. E. Check the harness and the wiring for abrasion and for pinch points.	Connectors	Results: The connectors and wiring are OK. Proceed to Test Step 2 Results: The connectors and/or wiring need repair. Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Verify that the repair eliminates the problem.
2. Attempt to Start the Engine A. Restore the electrical power to the ECM. B. At the control panel, send a start command to the engine. Note: The engine state must cycle through the "PRE-START" state prior to cranking the engine. The engine prelubrication must successfully be completed before the engine is allowed to exit "PRE-START". The crank cycle will continue for a time that is equal to the crank duration that has been programmed. The crank cycle may continue only until the engine speed exceeds the crank terminate speed. C. Turn the main disconnect switch to the OFF position.	Start - Up Engine	Results: The engine state parameter displays "CRANKING". The engine cranks. Repair: The engine starting system appears to be operating correctly. If an intermittent problem with the starting system is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect " for information that is related to troubleshooting intermittent electrical problems. If you are troubleshooting a problem with the manual override control for the starting system, proceed to Test Step 3 Results: The status for the engine state parameter displays "CRANKING". The engine does not crank. Ensure that the circuit breaker for the engine starting system and the main circuit breaker have not been tripped. If the circuit breakers are OK, proceed to Test Step 5.
3. Check the Signal for the Manual Override at the Engine Interface Connector (EIC) A. Restore the electrical power to the ECM. B. At the engine interface connector, remove the appropriate wire that is for the appropriate override switch. a. For starter 1, remove the wire from terminal location 26 from the engine interface connector. b. For starter 2, remove the wire from terminal location 27 ) from the engine interface connector. C. With the override switch in the ON position, use a multimeter to check the voltage at the loose end of the wire. D. Turn the main disconnect switch to the OFF position.	24 ± 3 VDC	Results: The voltage is 24 ± 3 VDC. The wiring that has been installed by the customer is OK. Proceed to Test Step 5 Results: The voltage is not 24 ± 3 VDC. Repair: There is a problem in the wiring between the ECM and the EIC. There may be a problem with the ECM. Perform the necessary repairs. Verify that the original problem has been resolved. Verify that the repair eliminates the problem. If the problem is not resolved, proceed to Test Step 4.
4. Check the Signal for the Manual Override at the ECM A. Turn the main disconnect switch to the OFF position. B. At the ECM connector J1/P1, remove wire P1-62 that is for the override switch. B. Turn the battery disconnect switch to the ON position. Place the override switch in the ON position. C. Use a multimeter to check the voltage between terminal P1-62 and engine ground. D. Turn the main disconnect switch to the OFF position. Place the override switch in the OFF position. Restore the wiring to the original configuration.	24 ± 3 VDC	Results: The voltage is 24 ± 3 VDC. Proceed to Test Step 5 Results: The voltage is not 24 ± 3 VDC. Repair: There is a problem with the ECM. Replace the ECM. Refer to Troubleshooting, "Test ECM Mode". Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance. Verify that the repair eliminated the problem.
5. Check for Active Diagnostic Codes A. Connect Cat ET to the service tool connector. B. Restore the electrical power to the ECM. C. Select diagnostic tests from Cat ET. D. Select the "Override Parameters" screen on Cat ET. E. Activate the override for the appropriate starting system for your application. F. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes for the starting system. Note: Wait at least 30 seconds in order for the diagnostic code to become active. G. Deactivate the override for the starting system. H. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. I. Turn the main disconnect switch to the OFF position.	Active Diagnostic Codes	Results: No diagnostic codes are active, but a problem is suspected in the circuit for the starting system. Repair: The circuit for the starting system appears to be operating correctly between the ECM and the starting motor magnetic switch. Isolate the starting motor magnetic switch from the primary circuit and the secondary circuit. Test the operation of the switch. If a problem with the switch is discovered, replace the switch. If the switch is OK, there is a problem in the circuit to the starting motors. There may be a problem in the power cables from the batteries to the starting motors. Check each of the circuits for problems. Check the operation of the starting motors. Perform the necessary repairs. Verify that the repair eliminates the problem. Results: A -6 diagnostic code is active at this time. Proceed to Test Step 7 Results: A -5 diagnostic code is active at this time. Proceed to Test Step 9
6. Create an Open at the Connector for the Starting Motor Magnetic Switch A. Disconnect the connector from the starting motor magnetic switch for the appropriate starting system. B. Restore the electrical power to the ECM. C. Select diagnostic tests from Cat ET. D. Select the "Override Parameters" screen on Cat ET. E. Activate the override for the starting system. F. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic code to become active. G. Deactivate the override for the starting system. H. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. I. Turn the main disconnect switch to the OFF position.	Active Diagnostic Codes	Results: A -5 diagnostic code became active after disconnecting the connector for the starting motor magnetic switch. Repair: Temporarily install a new starting motor magnetic switch. Verify that there are no active diagnostic codes for the starting system. Clear any logged diagnostic codes. Verify that the repair eliminates the problem. Results: A -6 diagnostic code remains active. There is a short between the connector for the starting motor magnetic switch and the ECM. Proceed to Test Step 7
7. Create an Open Circuit at the Connector for the Crank Relay A. Disconnect the relay connector for the power circuit that is for the appropriate starting system. Refer to Illustration 1 for the schematic of the circuit. B. Turn the battery disconnect switch to the ON position. C. Select diagnostic tests from Cat ET. D. Select the "Override Parameters" screen on Cat ET. E. Activate the override for the appropriate starting system. F. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic code to become active. G. Deactivate the override for the starting system. H. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. I. Turn the battery disconnect switch to the OFF position.	Open Circuit	Results: A -5 diagnostic code became active after disconnecting the crank relay at the connector. Repair: Temporarily install a new relay. Check for active diagnostic codes. If the -6 diagnostic code remains active after replacing the relay, there is a short in the harness. Check the harness from the relay to the starting motor magnetic switch. Repair the harness or replace the harness. Clear any logged diagnostic codes. Verify that the original problem has been resolved. Results: A -6 diagnostic code remains active. There is a short between the connector for the relay and the ECM. There may be a problem with the ECM. Proceed to Test Step 10
8. Create a Short at the Connector for the Starting Motor Magnetic Switch A. Disconnect the connector for the starting motor magnetic switch. Install a jumper wire between the terminals at the connector for the switch. Refer to Illustration 1 for the schematic of the circuit. B. Restore the electrical power to the ECM. C. Select diagnostic tests from Cat ET. D. Select the "Override Parameters" screen on Cat ET. E. Activate the override for the starting system. F. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic code to become active. G. Turn the main disconnect switch to the OFF position.	Short	Results: A -6 diagnostic code is active when the jumper wire is installed. Repair: There is a problem with the starting motor magnetic switch. Temporarily install a new switch. Verify that there are no active diagnostic codes for the starting system. Clear any logged diagnostic codes. Verify that the repair eliminates the problem. Results: The -5 diagnostic code remains active with the jumper in place. Verify that the wire at terminal 2 of the connector for the switch has continuity to the −Battery. If the return circuit is OK, the open circuit is between the ECM and the connector for the starting motor magnetic switch. Proceed to Test Step 9
9. Create a Short at the Connector for the Crank Relay A. Disconnect the relay for the power circuit and the relay for the return circuit from the connectors at the control box. Refer to Illustration 1 for the schematic of the circuit. B. Fabricate a jumper wire that is long enough to create a test circuit between the two relay connectors. Crimp spade terminals to each end of each of the jumper wire. C. Install one end of the jumper wire into terminal 3 at each of the relay connectors. D. Restore the electrical power to the ECM. E. Select diagnostic tests from Cat ET. F. Select the "Override Parameters" screen on Cat ET. G. Activate the override for the starting system. H. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic code to become active. I. Deactivate the override for the starting system. J. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. K. Turn the main disconnect switch to the OFF position.	Crank Relay	Results: The engine harness and the ECM are OK. Repair: Temporarily replace each of the relays. Check if replacement of the relays has corrected the original problem. If the problem has not been resolved, there is a problem in the harness between the relay and the starting motor magnetic switch. Repair the harness or replace the harness. Verify that the repair eliminates the problem. Results: The -5 diagnostic code remains active with the jumper in place. There is an open circuit between the ECM and the connector for the crank relay. There may be a problem with the ECM. Proceed to Test Step 10
10. Check the Operation of the ECM by Creating an Open at the ECM Connector: A. Disconnect the J2/P2 ECM connector. B. Remove the wires for the appropriate starting system from the output driver and the return circuit at the ECM connector. Refer to Illustration 1 for the schematic of the circuit. C. Fabricate two jumper wires that are long enough to create a test circuit across the ECM connector. Crimp connector sockets to each end of the jumper wire. D. Install a wire jumper into each of these terminal locations. Ensure that the wire jumpers do not come in contact with any other wire in the harness or in contact with engine ground. E. Reconnect the ECM connector. F. Restore the electrical power to the ECM. G. Select diagnostic tests from Cat ET. H. Select the "Override Parameters" screen on Cat ET. I. Activate the override for the appropriate starting system. J. Monitor the active diagnostic code screen on Cat ET. Note: Wait at least 30 seconds in order for the diagnostic code to become active. K. Deactivate the override. L. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. M. Turn the main disconnect switch to the OFF position.	Open	Results: The ECM is operating properly. The problem is in the wiring between the ECM and the connector for the crank relay. Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Verify that the repair eliminates the problem. Results: One of the following conditions exists: The -5 diagnostic code is not active when the wire jumpers are open. The -6 diagnostic code is not active when the wire jumpers are shorted together. Repair: There is a problem with the ECM. Replace the ECM. Refer to Troubleshooting, "Test ECM Mode". Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance.
11. Check the Operation of the ECM by Creating a Short Circuit at the ECM Connector. A. Connect the loose ends of the jumper wires. B. Restore the electrical power to the ECM. C. Select diagnostic tests from Cat ET. D. Select the "Override Parameters" screen on Cat ET. E. Activate the override for the appropriate starting system. F. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic code to become active. G. Deactivate the override. H. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active. I. Turn the main disconnect switch to the OFF position. J. Restore the wiring to the original configuration.	Short	Results: The ECM is operating properly. The problem is in the wiring between the ECM and the connector for the crank relay. Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Verify that the repair eliminates the problem. Results: One of the following conditions exists: The -5 diagnostic code is not active when the wire jumpers are open. The -6 diagnostic code is not active when the wire jumpers are shorted together. Repair: There is a problem with the ECM. Replace the ECM. Refer to Troubleshooting, "Test ECM Mode". Note: Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN) for assistance.