P0027

DTC P0027 Exhaust Throttle Control Valve Performance

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. When the proper enabling conditions are met the ECM monitors exhaust brake valve opening and closing while monitoring the mass air flow (MAF) signal. An expected MAF difference should be detected between the closed and open positions. If the ECM detects the MAF difference less than expected this DTC will set.

Condition for Running the DTC

^ DTCs P0079 P0080 P0101 P0102 P0103 P0112 P0113 P0116 P0117 P0118 P0201 - P0204 P0261 P0264 P0267 P0270 P02E2 P02E3 P02E7 P02E8 P02E9 P0300 P0301 - P0304 P0335 P0336 P0401 P0403 P0404 P0405 P0406 P0500 P0506 P0507 P0602 P0652 P0653 P1125 P1293 P2002 P2146-P2151 P2227 P2228 P2229 P2454 P2455 and P268A are not set.
^ The battery voltage is between 10 to 16 volts.
^ The ignition switch is ON.
^ The engine speed is between 550 to 1050 RPM and does not vary more than 30 RPM.
^ The vehicle is stationary.
^ The accelerator pedal is not depressed.
^ The barometric pressure is more than 11 psi (75 kPa).
^ The intake air temperature is more than 19°F (-7°C).
^ The engine coolant temperature is between 19 to 1 98°F (-7 to 92°C).
^ The intake airflow valve position is more than 50%.
^ The turbocharger control is under normal operation.
^ The exhaust brake valve is commanded ON (during engine warm-up OR during manual DPF regeneration).
^ The PTO control is not running.

Condition for Setting the DTC

^ The ECM detects that the MAF amount is not within the calculated range during the engine warm up control or DPF regeneration control. This diagnostic runs continuously while in either one of these two modes. This DTC indicates an open or stuck closed exhaust brake valve.

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 P0027 sets in the ECM. Diagnose only DTC P0027.

^ If an intermittent condition is suspected refer to Intermittent Conditions in this section.
^ A sticking or intermittently sticking the exhaust brake valve may set this DTC.
^ Misrouted vacuum hoses may set this DTC.
^ Loss of vacuum pressure or vacuum pump problem sets this DTC.

Circuit System Testing DTC P0027