C-10, C-12, C-15 and C-16 Industrial Engines – Low Power/Poor or No Response to Throttle

Probable Causes

  • Diagnostic codes

  • Event codes

  • Engine rating

  • Programmable parameters

  • Cold mode

  • Altitude derate

  • Electrical connectors

  • PTO enable switch

  • Intermediate speed switch

  • Throttle signal

  • Circuit for electronic unit injectors

  • Fuel supply

  • Turbocharger outlet pressure sensor (intake manifold air), rated fuel position and/or FRC fuel position

  • Air inlet and exhaust system

Recommended Actions

Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high rpm, full load and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.

Diagnostic Codes and Event Codes

Certain diagnostic codes and/or event codes may cause poor performance. Connect the Caterpillar Electronic Technician (ET) and check for active codes and for logged codes. Troubleshoot any codes that are present before continuing with this procedure.

Engine Rating

Verify that the correct engine rating is being used for the application.

Programmable Parameters

Check the following parameters on Cat ET:

  • “Throttle Position Sensor”

  • “Desired Speed Input Configuration”

  • “Direct Fuel Control Mode”

Determine the type of throttle that is used in the application. Program the parameters to match the type of throttle that is used. Refer to Troubleshooting, “Throttle Position Sensor Circuit – Test” for more information.

Note: If the parameters are not programmed correctly, then the engine will have poor performance.

Cold Mode

Monitor the status screen on Cat ET in order to verify that the engine has exited cold mode. Observe the reading for coolant temperature on Cat ET. The engine should exit cold mode whenever the coolant temperature is above 18 °C (64°F).

Altitude Derate

The engine may be derated due to high elevation. Connect Cat ET to the service tool connector. Check for an active engine derate on the status screens.

Note: There are no event codes that are associated with the altitude derate.

Electrical Connections to the ECM

Check the associated wiring for damage, abrasion, corrosion or incorrect attachment. Refer to Troubleshooting, “Electrical Connectors – Inspect” for additional information.

PTO Enable Switch

Connect Cat ET and verify that the “PTO enable switch” is not engaged. Remove J1-56 PTO enable switch and cycle power to the ECM. Verify that the problem is still present. If the problem is still present, reattach the wires and continue to next step. If the problem is resolved, refer to Troubleshooting, “Switch Circuits – Test”.

Intermediate Speed Switch

Connect Cat ET and verify that the intermediate speed switch is not engaged. Remove J1-45 (intermediate speed) and cycle power to the ECM. Verify that the problem is still present. If the problem is still present, reattach the wires and continue to next step. If the problem is resolved, refer to Troubleshooting, “Switch Circuits – Test”.

Throttle Signal

Connect Cat ET to the service tool connector. View the status for the throttle position on the status screen. Operate the throttle from the low idle position to the high idle position. The status should be 0 percent at low idle and the status should be 100 percent at high idle. If the status cannot operate in the full range, refer to Troubleshooting, “Throttle Position Sensor – Calibrate”.

Diagnostic codes that are related to the J1939 data link will prevent correct operation of the throttle if the throttle position is transmitted over the data link. If there is a problem with the data link, the engine will remain at low idle until the data link is repaired.

Circuit for the Electronic Unit Injector

Inspect the J2/P2 ECM connector and the J300/P300 unit injector connector for proper connections. Refer to Troubleshooting, ” Electrical Connectors – Inspect”. Connect Cat ET and cut out each cylinder in order to isolate the misfiring cylinder or cylinders. If the results are inconclusive, shut off half of the cylinders and repeat the cylinder cutout test on the active cylinders that are remaining in order to locate those cylinders that are missing. Refer to Troubleshooting, “Injector Solenoid Circuit – Test”.

Fuel Supply

Check for a problem with the fuel supply and verify the fuel pressure. Verify that the fuel pressure sensor P209/J209 is installed. For further information, refer to Testing and Adjusting, “Fuel System”.

Turbocharger Outlet Pressure Sensor (Intake Manifold Air), Rated Fuel Position and/or FRC Fuel Position

  1. With the engine at full load, monitor “Fuel Position” and “Rated Fuel Limit” on the status screen. If “Fuel Position” does not equal “Rated Fuel Limit”, then check air inlet manifold pressure.
  1. Verify that there are no active diagnostic codes that are associated with the turbocharger outlet pressure sensor (intake manifold air) or with the atmospheric pressure sensor.
  1. Monitor air inlet manifold pressure and atmospheric pressure for normal operation on the status screen.

Note: Atmospheric pressure is not a default parameter on the status screen. A new parameter screen must be set up in order to monitor the atmospheric pressure sensor.

Air Inlet and Exhaust System

Check the air inlet and exhaust systems for restrictions and for leaks. Refer to Testing and Adjusting, “Air Inlet and Exhaust System”. Look for an indication of the warning lamp or restriction indicators that are tripped if the filters are equipped with these devices. These indicators are associated with plugged filters. Replace the plugged air filters or clean the plugged air filters per the guidelines for operation and maintenance. Repair any leaks that are found in the system.