Cummins ISX11.9 CM2250 – Service Manual Engine Brake – Low Retarding Power or Slow to Activate

Interview the operator to verify the complaint

Refer to Driveability-General Information, the Driveability/Low-Power Customer Complaint Form, and the Driveability Checklist at the end of Section TS. Follow the instructions on the forms before continuing with this tree.

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF in the Fault Code Troubleshooting Manual, Bulletin
4022225 for fault code troubleshooting.

Programmable parameters or selected features are not correct

Check the programmable parameters and the selected features with an electronic service tool. Set the parameters and features again, if necessary. Refer to
Procedure 019-078 in Section 19
.

Engine is cold

Allow the engine to warm to operating temperature. If the engine will not reach operating temperature, refer to the Coolant Temperature Below Normal symptom tree in Section TS.

Engine brake adjustment is not correct

Adjust the engine brakes. Refer to
Procedure 020-024 in Section 20
.

Engine brake on/off switch or circuit is malfunctioning

Check the engine brake on/off switch and circuit. Refer to Procedure 019-034 and
Procedure 019-035 in Section 19.

Engine brake solenoid, harness or connectors are loose, broken or have an open circuit

Check the engine brake circuit, solenoid, and harness connectors. .

Engine electrical ground is malfunctioning

Check for poor battery and chassis grounds. Check ground wires or cables for loose connections. Check the following grounds, make sure they are secure, clean, and on a non-painted surface; engine block ground, chassis (or frame rail) grounds, ECM grounds, alternator and starter negative posts. Disconnect and clean the battery cable connections.

Engine brake harness connectors are loose or broken

Check the engine brake harness connectors.

Air in the lubricating oil system

Check the oil level. If the level is high, contact a Cummins® Authorized Repair Location.

Lubricating oil leak (internal)

Check the engine brake control valve and the engine brake piston. Refer to Procedure 020-024 in Section 20.

Engine brake solenoid(s) is malfunctioning

Refer to Procedure 020-012 in Section 20.

Engine brake control valve(s) is malfunctioning

Check the engine brake control valve(s). Replace the engine brake control valve(s) if necessary. Refer to Procedure 020-024 in Section 20.

Engine brake lubricating oil passage is restricted

Check the engine brake assembly for restriction. Refer to Procedure 020-024 in Section 20.

Turbocharger is malfunctioning

Perform diagnostics to determine if the turbocharger has failed. Replace the turbocharger as necessary. Refer to the Engine Performance Troubleshooting Tree in Section TT.