P166A

DTC P166A

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

DTC Descriptor
DTC P166A
- Exhaust Control Valve Control Circuit

Diagnostic Fault Information





Circuit/System Description

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

Conditions for Running the DTC

* Ignition ON.
* Ignition voltage is greater than 10 volts.

Conditions for Setting the DTC

* Exhaust tail pipe flow valve control module detects short to voltage on exhaust valve solenoid supply voltage circuit.
* Exhaust tail pipe flow valve 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.
* A DIC message and/or a warning indicator may be displayed.

Conditions for Clearing the DTC

* The condition for setting the DTC is no longer present.
* The history DTC is cleared when a current DTC is not detected in 100 consecutive drive cycles.

Reference Information
Schematic Reference

Exhaust System Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Exhaust Tail Pipe Flow Control System Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the exhaust tail pipe flow control valve solenoid connector.
2. Test for less than 5 ohms between the ground circuit terminal 1 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the supply voltage circuit terminal 2 and ground.
4. Ignition ON, command the exhaust flow control relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the exhaust tail pipe flow valve control module.

• If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace exhaust tail pipe flow valve control module.

5. If all circuits test normal, replace the exhaust tail pipe flow valve solenoid. If the DTC resets, replace the exhaust tail pipe flow valve control module.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Exhaust Tail Pipe Flow Control Valve Solenoid Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for exhaust tail pipe flow valve control module replacement, setup, and programming