The probable root causes are listed in order below:
• Diagnostic codes
• Engine software
• Engine speed/timing signal
• Key switch
• Communications between the ECM and the electronic service tool
• Aftermarket engine protection devices
• Power to ECM
• Personality Module
• Electrical connections to the electronic unit injector
• Theft deterrent
• Fuel supply
• Combustion problem
1. Check for active diagnostic codes.
a. Connect the electronic service tool to the data link connector.
b. Check for active diagnostic codes. Certain diagnostic codes will prevent the engine from starting.
c. Troubleshoot any diagnostic codes that are present before continuing with this procedure.
2. Check the engine software.
Verify that the software that is installed matches the application.
A new ECM has a personality module that is not programmed. The engine will not start until the personality module has been flashed. Also, the ECM will not communicate until the personality module has been flashed.
Note: The personality module on a new ECM will not be programmed. Use “WinFlash” to program a new ECM.
3. Check the engine speed/timing signal.
a. Observe the engine rpm on the electronic service tool while the engine is being cranked.
This may require the electronic service tool to be powered directly by the vehicle batteries or this may require the electronic service tool to be powered directly by a separate power source (12 VDC). Refer to Illustration 22.
If the electronic service tool displays 0 rpm and the engine is being cranked, there is a problem in the circuit for the primary engine speed/timing sensor or the circuit for the secondary engine speed/timing sensor. Refer to Troubleshooting, “Engine Speed/Timing Circuit – Test”.
If an engine rpm is present, check the sensor installation. If the sensor is not properly installed, the sensor may read RPM but the sensor may not be able to sense the tooth pattern. The ability to sense the tooth pattern is necessary to determine the cylinder position. Engine rpm is present when the engine rpm is 50 rpm or more.
4. Check the key switch.
a. Access the status for “Ignition Key Switch”.
b. Slowly cycle the key switch ON and OFF while the status of the key switch is being monitored. The status should indicate the state of the switch.
If the ECM will not communicate and the key switch is in the ON position, refer to Step 6.
Note: If the Engine Shutdown Output feature is used, the status for the key switch may indicate
that the switch is ON even though the key switch is turned to the OFF position.
5. Check the communications between the ECM and the electronic service tool.
a. Ensure that the key switch is in the ON position. Attempt to access one of the status screens on the electronic service tool.
If the electronic service tool indicates that the ECM will not communicate go to Step 6. If the ECM communicates go to Step 8.
6. Check aftermarket engine protection devices.
These devices usually interrupt power to the ECM and the ECM will not communicate with the electronic service tool.
a. Check for the correct installation of the aftermarket engine protection device.
b. Check for the correct operation of the aftermarket engine protection device.
c. Verify that the ECM is receiving battery voltage.
7. Check the electrical power supply to the ECM.
a. Check the power connection of the ECM and the ground connection of the ECM.
b. Verify that the ECM is receiving battery voltage when the key switch is turned ON.
Refer to Troubleshooting, “Ignition Key Switch Circuit and Battery Supply Circuit – Test”.
8. Check the ECM.
Before replacing the ECM, try to flash program the existing ECM. Refer to Troubleshooting, “Flash Programming”.
If the ECM is suspected of being the problem, temporarily connect a test ECM. This will show whether the problem has been resolved or the problem has not been resolved.
9. Check the electrical connections to the electronic unit injectors.
a. Ensure that the front valve cover connector and the rear valve cover connector are fully connected and ensure that the valve cover connectors are free of corrosion.
b. Check for logged diagnostic codes that are related to the cylinder. Go to Troubleshooting,
“Injector Solenoid Circuit – Test” if diagnostic codes that are related to the cylinder are present.
10. Ensure that the theft deterrent (if equipped) is not active. Turn the key switch to the ON position.
Observe the display screen on Messenger.
If the display screen on Messenger indicates that the theft deterrent is enabled, the Theft Deterrent Passwords must be entered before the engine will start.
11. Check the fuel supply.
a. 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.
b. Check the fuel quality. Refer to Testing and Adjusting, “Fuel Quality – Test”. Also refer to Truck Performance and Driveability Diagnostic Guide, LEBT3477.
c. Check the fuel pressure. Refer to Testing and Adjusting, “Fuel System Pressure – Test”.
d. Ensure that the fuel system has been primed. Refer to Testing and Adjusting, “Fuel System – Prime”.
e. Check for fuel supply lines that are restricted.
f. Check the fuel filters.
g. If the temperature is below 0 C (32 F), check for solidified fuel (wax).
12. Check for combustion problems.
Examples of combustion problems are shown in the following list:
• Outside temperatures are too cold.
• Mechanical problem