Cummins ISX11.9 CM2250 – Service Manual Engine Brake Does Not Operate

Engine brake on/off switch is off

Turn on the switch.

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
.

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF in the Fault Code Troubleshooting Manual, Bulletin
4022225.

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. Refer to
Procedure 020-012 in Section 20.

Engine brake harness connectors are loose or broken

Check the engine brake harness connectors.

Clutch switch or circuit is malfunctioning

Check the clutch switch adjustment, switch, and circuit. Refer to Procedure 019-009 and
Procedure 019-010 in Section 19.

Accelerator pedal or lever position sensor or circuit is malfunctioning

Check for foot pedal restriction. Check the accelerator pedal or lever position sensor and circuit. Refer to
Procedure 019-085 in Section 19
.

Service brake pressure switch or circuit is malfunctioning

Check the service brake pressure switch and circuit. Refer to the OEM service manual.

Engine electrical ground is malfunctioning

Check engine ground to chassis and chassis ground to battery negative (-) post. Refer to the OEM service manual and
Procedure 013-009 in Section 13.

Lubricating oil leak (internal)

Check the engine brake control valve and the engine brake piston. Refer to Procedure 020-012 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
.

Engine brake adjustment is not correct

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