ISX12/ISX11.9 CM2250 Fault Code: 3612 | SPN: 3361 | FMI: 7Aftertreatment 1 Diesel Exhaust Fluid Dosing Unit – Mechanical System Not Responding or Out of Adjustment

Overview

Circuit Description

The aftertreatment 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 ECM provides a battery voltage supply and a ground to the diesel exhaust fluid dosing unit. The ECM 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 original equipment manufacturer (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 Engine Control Module (ECM) detected a certain amount of incomplete purge cycles while monitoring the diesel exhaust fluid dosing system.

Action Taken When the Fault Code is Active

• The ECM logs the fault code immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code

• This fault code will go inactive upon successful completion of a diesel exhaust fluid dosing system purge cycle.
• The purge counter reset function can be found in the «Advanced ECM Data» menu of the recommended Cummins® electronic service tool or equivalent.
• Once the purge counters have been reset, the fault code will go inactive and can then be cleared with the recommended Cummins® electronic service tool or equivalent.
• The “Reset All Faults” command in the recommended Cummins® electronic service tool or equivalent can be used to clear active and inactive faults.

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.