ELECTRICAL AR 3378362 - Caterpillar

Probable Causes
Codes
Check valve
Parameters
Inlet air restriction
Light loads
Thermocouple
Valve lash
Low compressionRecommended Actions
Table 3
Troubleshooting Test Steps Values Results
1. 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: An associated code is active.
Repair: Troubleshoot any associated codes before continuing with this test.
Result: A code is active or logged.
Proceed to Test Step 2.
2. Inspect the Check Valve
Note: The check valve may be stuck. The check valve must move freely to prevent fuel from continuously entering the precombustion chamber.
Check Valve
Result: The check valve is OK.
Proceed to Test Step 3.
Result: The check valve is NOT OK.
Repair: Clean or replace the check valve. Clean with a nonflammable solvent that will not leave residue.
If the problem is not resolved, proceed to Test Step 3.
3. Check for Incorrect Monitoring System Parameters
A. Connect Cat ET.
B. Use Cat ET to verify that the correct parameters are being used.
- Exhaust temperature module
- Exhaust port temperatures
Parameters
Result: The parameters are correct.
Proceed to Test Step 4.
Result: The parameters are not correct.
Repair: Input the correct parameters. Refer to Troubleshooting, "Event Codes" for additional information.
If the problem is not resolved, proceed to Test Step 4.
4. Check for Inlet Air Restriction
Note: Inlet air restriction can cause uneven exhaust port temperatures. Cylinders at the front half of the engine may have exhaust port temperatures that are lower than the exhaust port temperatures for the cylinders at the rear half of the engine by 10 °C to 20 °C (18 °F to 36 °F).
A. Check the air filter restriction indicator, if equipped. Refer to the Operation and Maintenance Manual for additional information.
B. Measure the inlet air restriction for each turbocharger. Refer to Troubleshooting, "Inlet Air Is Restricted" for additional information.
Restriction
Result: The inlet air restriction is OK.
Proceed to Test Step 5.
Result: The inlet air restriction is NOT OK. An imbalance in the system is discovered.
Repair: Repair or replace damaged inlet air system components. Equalize the inlet air restriction for each of the turbochargers.
If the problem is not resolved, proceed to Test Step 5.
5. Check for a Cylinder Misfire
Note: Operation with a low load can result in low exhaust temperatures.
A. Operate the engine at low idle or near low idle to detect a misfire problem.
Misfire
Result: There is not a cylinder misfire.
Proceed to Test Step 6.
Result: There is a cylinder misfire.
Repair: Troubleshoot the cause of the misfire. Refer to Troubleshooting, "Engine Misfires, Runs Rough or Is Unstable" for additional information.
If the problem is not resolved, proceed to Test Step 6.
6. Check for Faulty Thermocouples
A. Observe the temperatures from the thermocouples after the engine is shut off.
When the engine is operating properly, the temperatures from similar locations are reduced at a similar rate. Also, the temperatures from similar locations are comparable.
Thermocouples
Result: The thermocouples are OK.
Proceed to Test Step 7.
Result: The thermocouples are NOT OK.
Repair: Switch the suspect thermocouple for another thermocouple. If the temperature problem follows the thermocouple, replace the suspect thermocouple.
If the temperature problem stays at the original location of the suspect thermocouple, investigate the