P156B

DTC P156B Diesel Exhaust Fluid (DEF) Control Module System Voltage High

Circuit Description

The DEF control module monitors the battery voltage on the battery voltage feed terminal and makes sure that the voltage stays within the proper range. If the DEF control module detects an excessively high battery voltage, this DTC will set.

Condition for Running the DTC

- The ignition switch is ON.
- The engine is running.

Condition for Setting the DTC

- The DEF control module detects that the battery voltage feed circuit is greater than 16 volts for 10 seconds.

Action Taken When the DTC Sets

- The DEF control module requests the ECM to illuminate the SVS lamp. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type C.
- The DEF control module and the ECM apply defaulted warning actions. Refer to Default Action and Fail-Safe List.

Conditions for Clearing the DTC

- Refer to DTC Type Definitions for Conditions for Clearing the DTC - Type C.

Diagnostic Aids

- A charging system problem may set this DTC.
- Jump starting the vehicle or a battery charger may have set this DTC.

Circuit / System Testing DTC P156B