C7 and C9 Industrial Engines Troubleshooting – Engine Shutdown Occurs Intermittently

Probable Causes


  • Air shutoff 
  • Active codes and logged codes 
  • Unstable fuel supply 
  • Electrical connections 
  • Switches 
  • Circuit protection 
  • Engine speed/timing 

Recommended Actions

Note: The procedures have been listed in order of probability. Complete the procedures in order.

Table 1
Troubleshooting Test Steps Values Results
1. Air Shutoff

A. Check the operation of the air shutoff system.

Air shutoff Result: The air shutoff system is operating properly.

Proceed to Test Step 2.

Result: The air shutoff system is not operating properly.

Repair: Repair the air shutoff system. Refer to Troubleshooting, “Air Shutoff – Test” for troubleshooting information.

If the repair does not resolve the problem, proceed to Test Step 2.

2. Check for Codes

A. Connect Cat® Electronic Technician (ET) to the service tool connector.

B. Look for active codes that are associated with the system for the event code.

Codes Result: There are active codes.

Repair: Troubleshoot any active codes before continuing with this procedure.

Result: There are no active codes.

Proceed to Test Step 3.

3. Electrical Connections

A. Check for the correct installation of the ECM J1/P1 and the J2/P2 connectors. Check for correct installation of the fuel injector connectors.

Connectors Result: There are suspect connectors.

Repair: Repair connectors that are suspect or replace connectors that are suspect.

Perform the “Wiggle Test” on Cat ET.

Result: There are no suspect connectors.

Proceed to Test Step 4.

4. Unstable Fuel Supply

If there is an immediate engine shutdown, troubleshoot the electrical connectors before proceeding with this procedure.

A. Inspect the fuel system. Refer to Systems Operation/Testing and Adjusting, “Fuel System – Inspect” for additional information.

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

B. Check fuel quality. Check the fuel tank for debris or foreign objects which may block the fuel supply.

C. Check the filtered fuel pressure while the engine is being cranked.

Fuel Result: The fuel quality is OK.

Proceed to Test Step 5.

Result: The fuel quality is not OK.

Repair: Replace the fuel. Verify that the repair eliminated the problem.

5. Electrical Connections

A. Check the power and ground connections to the ECM. Refer to Troubleshooting, “Electrical Power Supply – Test”.

Electrical connectors Result: The electrical connections are OK.

Proceed to Test Step 6.

Result: The electrical connections are not OK.

Repair: Repair or replace the damaged connectors.

If the repair does not eliminate the problem, proceed to Test Step 6.

6. Switches

A. Check the keyswitch input to the ECM.

B. Check any engine shutdown switches and associated wiring.

Switches Result: The shutdown switches and wiring are OK.

Proceed to Test Step 7.

Result: The shutdown switches and wiring are not OK.

Repair: Make the necessary repairs.

If the repair does not eliminate the problem, proceed to Test Step 7.

7. Circuit Protection

A. Inspect the wires and connectors to all circuit protection for the engine.

B. Check the device for circuit protection.

Circuit protection Result The circuit protection device is tripped.

Repair: Reset the circuit breakers if the circuit breakers are tripped. If necessary, replace fuses (if equipped). Prior to returning the engine to service, determine the condition that caused the circuit breaker to trip. Make the necessary repairs.

Result The circuit protection device is not tripped.

Proceed to Test Step 8.

8. Engine Speed/Timing

A. Thoroughly inspect the connectors for the engine speed/timing sensors.

B. Crank the engine, if the engine starts and no speed timing codes are logged, the speed timing circuit is operating properly.

Speed/Timing Result: The Speed/Timing sensor circuit is not operating properly.

Repair: Make the necessary repairs, Verify that the repair eliminated the problem. Refer to Troubleshooting, “Speed/Timing `- Test”


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