P0079

DTC P0079 Exhaust Valve Control Circuit Low Voltage

Circuit Description

The ECM controls the exhaust brake solenoid valve which supplies vacuum pressure to the exhaust brake valve based on the vehicle running condition. The exhaust brake solenoid valve energizes to apply vacuum pressure to the diaphragm chamber of exhaust brake valve. If the ECM detects an open circuit or short to ground on the solenoid valve control circuit this DTC will set.

Condition for Running the DTC

^ DTC P0080 is not set.
^ The battery voltage is between 10 to 16 volts.
^ The ignition switch is ON.

Condition for Setting the DTC

^ The ECM detects a low voltage condition on the exhaust brake solenoid valve control circuit when the solenoid is commanded OFF.

Action Taken When the DTC Sets

^ The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type A.
^ The ECM inhibits accelerator pedal control.
^ The ECM inhibits EGR control.
^ The ECM inhibits DPF regeneration control.
^ The ECM inhibits cruise control.
^ The ECM inhibits PTO control.

Condition for Clearing the DTC

^ Refer to DTC Type Definitions for Condition for Clearing the MIL/DTC - Type A.

Diagnostic Aids

Important: DTC P0475 will set automatically in the TCM if DTC P0079 sets in the ECM. Diagnose only DTC P0079.

^ If an intermittent condition is suspected refer to intermittent conditions in this section.

Circuit System Testing DTC P0079