Cummins ISB4.5 CM2150 Fault Code: 1698 PID: SPN: 3489 FMI: 4 Air Supply Actuator – Voltage Below Normal or Shorted to Low Source.

Circuit Description
The aftertreatment diesel exhaust fluid (DEF) dosing unit air solenoid is used to enable and disable the truck air supply to the DEF pump. The air is used to transport the DEF to the DEF injector.

Component Location
The aftertreatment DEF dosing unit air solenoid is mounted to the back of the DEF pump. The DEF pump is original equipment manufacturer (OEM) mounted. Refer to the OEM service manual for more information.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes
This fault code is logged when the supply voltage to the air solenoid is greater than +12-VDC.

Action Taken When the Fault Code is Active
-The engine control module (ECM) illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately after the diagnostic runs and fails.
-DEF injection into the SCR aftertreatment system is disabled.
-Engine torque will be reduced.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.
-The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
-The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
-For On-Board Diagnostics (OBD) engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passes.
-The “Reset All Faults” command in INSITE™ electronic service tool can be used to clear active and inactive fault codes, as well as extinguish the MIL for OBD applications.

Possible Causes
-Open circuit in the air solenoid signal wire
-Open circuit in the air solenoid return wire
-Shorted to pin-to-pin air solenoid signal wire
-Malfunctioning air solenoid
-Malfunctioning DEF pump.