Component Tests and General Diagnostics

Exhaust Tail Pipe Flow Valve Mechanical System Diagnosis

Diagnostic Aids

System diagnosis includes reviewing the system Exhaust Tail Pipe Flow Control System Description and Operation (Description and Operation) . Reviewing the information will help determine when a malfunction exists. It will also help to determine if the condition described by the customer is a normal system operation. Refer to Symptoms - Engine Exhaust (Symptoms - Engine Exhaust) in order to identify the correct procedure for diagnosing the system.


A Scan Tool can be used to command the vacuum solenoid On or Off.

* Vacuum solenoid commanded OFF

- Engine vacuum is blocked to the exhaust flow control valves mechanically by the position of the solenoid valve.
- Exhaust flow control valve vacuum diagrams are vented to the atmosphere mechanically due to the position of the solenoid valve.
- Exhaust flow control valves are OPEN.
- Exhaust gases flow through the least restrictive passage in the mufflers.
- Exhaust gases exit all muffler tail pipes.

* Vacuum solenoid commanded ON

- Engine vacuum is sent to the exhaust flow control valve.
- Both exhaust flow control valves CLOSE.
- Exhaust gases must flow through a more restrictive passage within the mufflers.
- Exhaust gases exit only the outboard tail pipe of each muffler.