P166A

DTC P166A
DTC Descriptor
DTC P166A
Exhaust Control Valve Control Circuit

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection





Circuit/System Description
Exhaust flow control module (EFCM) receives throttle position sensor and RPM information via serial data from powertrain control module (PCM). The EFCM uses this information to determine if to command exhaust flow control valve solenoid ON or OFF. When commanded OFF the exhaust flow control valve solenoid allows vacuum to flow to close exhaust valve.

Conditions for Running the DTC
^ The ignition is ON.
^ Ignition voltage is greater than 8 volts.

Conditions for Setting the DTC
^ Exhaust flow control module detects short to voltage on exhaust valve solenoid supply voltage circuit.
^ Exhaust flow control module detects short to ground on exhaust valve solenoid supply voltage circuit.

Action Taken When the DTC Sets
Exhaust flow control valve defaults to open.

Conditions for Clearing the DTC
^ The condition for setting the DTC is no longer present and the DTC is cleared with a scan tool.
^ The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Reference Information
Schematic Reference
Exhaust System Schematics

Connector End View Reference
Exhaust System Connector End Views
Electrical Information Reference
^ Circuit Testing
^ Connector Repairs
^ Testing for Intermittent Conditions and Poor Connections
^ Wiring Repairs

Scan Tool Reference
Scan Tool Data List for EBCM

Circuit/System Testing
1. Ignition OFF, disconnect the exhaust flow control valve solenoid connector.
2. Ignition ON, measure for 0 volts between the exhaust valve solenoid supply voltage circuit and ground.
^ If over 0 volts, test for short to voltage in exhaust valve solenoid supply voltage circuit.
3. Ignition ON, use scan tool to command exhaust flow control relay ON, measure for 10 volts or above between the exhaust valve solenoid supply voltage circuit and ground.
^ If under 10 volts, test for short to ground in exhaust valve solenoid supply voltage circuit.
4. If all circuits test normal replace the Exhaust Flow Control Module.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

Exhaust Flow Control Module Replacement