Cummins ISX11.9 CM2250 (2010-12) Fault Code: 3612 PID: SPN: 3361 FMI: 7 Aftertreatment Diesel Exhaust Fluid Dosing Unit- Mechanical System Not Responding or Out of Adjustment

Circuit Description
The diesel exhaust fluid dosing unit performs many functions, one of which is to generate adequate diesel exhaust fluid pressure in the lines, using a pump, to allow for dosing. The diesel exhaust fluid controller provides a battery voltage supply and a ground to the diesel exhaust fluid dosing unit. The controller also supplies a signal to the dosing unit to control the diesel exhaust fluid output. This signal changes based on the diesel exhaust fluid pressure being commanded.

Component Location
The aftertreatment diesel exhaust fluid dosing unit location is OEM dependent. Refer to the OEM service manual.

Conditions for Running the Diagnostics
This diagnostic runs at initial key ON.

Conditions for Setting the Fault Codes
The ECM monitors and records occurrences of both successful and unsuccessful purge cycles of the diesel exhaust fluid dosing system. This fault is set active after a certain number of incomplete purge cycles have been detected.

Action Taken When the Fault Code is Active
The fault code will be set active immediately when the diagnostic runs and fails. This is a no lamp fault.
Conditions for Clearing the Fault Code
This fault code will not go inactive until the purge counters have been reset to zero using INSITE? electronic service tool.
The purge counter reset function can be found in the “Advanced ECM Data” menu of the INSITE? electronic service tool.
Once the purge counters have been reset, the fault code will go inactive and can then be cleared with INSITE? electronic service tool.

Shop Talk
The SCR system is programmed to automatically purge itself after the engine has been shut down. Immediately following key OFF, the diesel exhuast fluid (DEF) return valve will be actuated and the dosing unit will pump any DEF left in the lines and dosing unit back to the DEF tank. The purge cycle can take up to 60 seconds.

This is an information only fault code that indicates that something is not allowing the diesel exhaust fluid dosing unit to fully complete its purge cycle. Failure to complete the purge cycle could lead to deposits forming in the diesel exhaust fluid system or damage to the dosing unit caused by freezing of the diesel exhaust fluid. Make sure that battery power is not being removed from the SCR system immediately after engine shutdown via a main battery disconnect switch.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Cause:
1) ECM calibration
2) DEF wiring