Troubleshooting

Table 6
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
Note: Certain diagnostic codes may cause poor performance.
A. Use the electronic service tool to check for active or logged di-
agnostic codes.
Engine Derate
or Diagnostic
Codes
Result: A diagnostic code is present.
Repair: Troubleshoot the diagnostic code. Refer to Trou-
bleshooting, “Diagnostic Trouble Codes”.
Result: A diagnostic code is not present.
Proceed to Test Step 2.
2. Parameters in the Electronic Control Module (ECM)
A. Use the electronic service tool to verify that the correct param-
eters are being used. Refer to Troubleshooting, “Configuration
Parameters” for additional information.
Parameters Result: The parameters are not correct.
Repair: Input the correct parameters. Refer to Trouble-
shooting, “Configuration Parameters” for additional
information.
Result: The parameters are correct.
Proceed to Test Step 3.
3. Throttle Position Sensor/Throttle Switches
A. Turn the start switch to the ON position.
B. Run the engine until the speed is equal to the maximum no-
load speed.
C. Use the electronic service tool to make sure that the throttle is
set to reach the maximum no-load speed.
Electrical
connections
Result: The throttle response is not as expected.
Repair: If the maximum no-load speed cannot be obtained
refer to Troubleshooting, “Switch Circuits - Test (Throttle
Switch)” and Troubleshooting, “Mode Selection - Test”.
If the engine speed is erratic refer to Troubleshooting,
“Speed Control - Test”.
Result: All responses are normal.
Proceed to Test Step 4.
4. Air Intake and Exhaust System
A. Observe the engine warning lamp. Check for an air filter re-
striction indicator, if equipped. Replace plugged air filters. Refer
to the Operation and Maintenance Manual.
B. Check the air inlet and exhaust system for restrictions and/or
leaks. Refer to Systems Operation/Testing and Adjusting, “Air In-
let and Exhaust System - Inspect”.
Restrictions Result: There are restrictions in the air inlet or exhaust
system.
Repair: Make the necessary repairs, Refer to Systems
Operation/Testing and Adjusting, “Air Inlet and Exhaust
System - Inspect” for additional information.
Result: There are no restrictions in the air inlet or exhaust
system.
Proceed to Test Step 5.
5. Valve Lash
Note: The valve lash can affect the performance of the engine.
A. Check the valve lash. Refer to Systems Operation, Testing
and Adjusting, “Engine Valve Lash - Inspect”.
Valve lash Result: The valve lash is not correct.
Repair: Make any necessary repairs. Refer to Systems
Operation, Testing and Adjusting, “Engine Valve Lash -
Inspect”.
Result: The valve lash is correct.
Proceed to Test Step 6.
(continued)
32 UENR0612-07
Symptom Troubleshooting
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