3406E, C12, C15 and C18 Marine Engines Caterpillar

Note: If the vessel is equipped with a Multi-Station Control System (MSCS), refer to Service Manual, RENR7651, "Marine Multi-Station Control System" for the proper troubleshooting procedure.

Probable Causes

• Diagnostic codes

• ECM power supply

• Remote shutdown switch

• Starting motor solenoid or starting circuit

• Engine speed/timing

• Unit injectors

• Fuel supply

• Combustion problems

Recommended Actions

Diagnostic Codes and ECM Power Supply

Certain diagnostic codes may prevent the engine from starting. Connect the Caterpillar Electronic Technician (ET) and check for active codes and/or logged codes. Troubleshoot any codes that are present before continuing with this procedure.

Note: If Cat ET will not communicate with the ECM, the problem is most likely with the electrical power supply to the ECM. Refer to Troubleshooting, "Electrical Power Supply Circuit - Test".

Remote Shutdown Switch

Access the status screen on Cat ET that displays the remote shutdown switch status. The remote shutdown switch status is called "User Shutdown".

Table 1

"User Shutdown" Status	Switch Status	Measured Voltage at P61-36
ON	Negative battery	<0.9 VDC
OFF	Open Circuit	>10 VDC

If the voltage is not in the proper range, refer to Troubleshooting, "Switch Circuits - Test".

Starting Motor Solenoid or Starting Circuit

1. Test the operation of the starting motor solenoid.

2. Check the engine wiring to the starting motor solenoid.

3. Test the operation of the starting motor.

4. Inspect the starter motor pinion and the flywheel ring gear for damage.

Engine Speed/Timing

1. Crank the engine and observe the engine speed on the status screen of Cat ET. If Cat ET indicates zero rpm, refer to Troubleshooting, "Engine Speed/Timing Sensor Circuit - Test".

   Note: Upon initial cranking, the status for engine speed may indicate that the engine speed signal is abnormal. This message will be replaced with an engine speed once the ECM is able to calculate a speed from the signal from the engine speed/timing sensor.

2. Ensure that the timing reference gear is installed correctly. The engine will not start if the gear was installed backward. Check for proper orientation between the crankshaft and camshaft drive gears. Correct the orientation and/or replace the drive gear, if necessary. Refer to Disassembly and Assembly, "Camshaft - Remove and Install".

Unit Injectors

Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM. Refer to Troubleshooting, "Injector Solenoid Circuit - Test" for additional information.

Fuel Supply

1. Check the fuel level.

2. Monitor the exhaust for smoke while the engine is being cranked.

   If no smoke is present, there may be a problem with the fuel quality or there may be a problem with the fuel supply.

3. Check the fuel pressure. Refer to Systems Operation/Testing and Adjusting, "Fuel System Pressure - Test".

4. Ensure that the fuel system has been primed. Refer to Systems Operation/Testing and Adjusting, "Fuel System - Prime".

5. Check for fuel supply lines that are restricted.

6. Check the fuel filters.

7. Cold weather adversely affects the characteristics of the fuel. Refer to the applicable Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold weather operation.

Combustion Problems

Check for combustion problems. Combustion problems can be caused by cold ambient temperatures. Combustion can also be inhibited by mechanical problems.