P2261

P2261-TURBOCHARGER BYPASS VALVE - MECHANICAL





For a complete wiring diagram, refer to the Wiring Information. Electrical Diagrams

Theory of Operation

The turbocharger bypass valve (surge valve) is activated during a rapid throttle change from a boosted manifold pressure to a low manifold pressure (closed throttle). The surge valve allows excess pressure between the compressor and closed throttle to escape. If this does not happen the excess pressure pulsates against the compressor vanes. The diagnostic looks for these pressure pulsations from the Throttle Inlet Pressure sensor (TIP) during the activation of the surge valve and outlined engine operating conditions.

- When Monitored:
The first stage of this diagnostic runs under the following conditions: (1) The throttle goes from open to closed (deceleration), (2) The engine rpm is greater than 1200, (3) The throttle inlet pressure is 20 kPa higher than the barometric pressure, (4) The vehicle speed is greater than 30 mph, (5) The air flow through the engine is greater than 6 g/s.

The second stage of this diagnostic runs under the following conditions: (1) The throttle has been open for at least 0.5 seconds, (2) The first stage of the Surge Valve Stuck Closed diagnostic has failed, (3) The throttle position is greater than 2.0 volts, (4) The throttle inlet pressure is higher than the barometric pressure, (5) The engine rpm is greater than 1500, (6) The vehicle speed is greater than 30 mph, (7) The air flow through the engine is greater than 80 g/s, (8) The engine coolant temperature is greater than 20 C.

- Set Condition:
A pending fault is set only when both stages of the diagnostic have failed. The first stage fails when a rapid pulsation in the throttle inlet pressure is detected as the throttle goes from open to closed. The second stage fails when, under boost conditions, the surge valve is commanded open and the throttle inlet pressure does not decrease.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. DTC IS ACTIVE

NOTE: Diagnose and repair any related turbocharger solenoid or pressure sensor DTCs before continuing with this test.

NOTE: It may be necessary to test drive the vehicle within the DTC monitoring conditions in order to get this fault to reset.

1. Start the engine and allow it to reach normal operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

2. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Perform the CHECKING FOR AN INTERMITTENT DTC diagnostic procedure. Checking for an Intermittent DTC.

2. AIR FILTER
1. Turn the ignition off.
2. Remove and inspect the Air Filter for any condition that may cause air flow restriction.

Were any problems found?

Yes

- Replace the Air Filter element.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Go To 3

3. CHECK FOR INTAKE AND EXHAUST SYSTEM RESTRICTIONS

NOTE: Damaged, restricted or poorly connected intake and turbocharger related tubes can cause this DTC to set.

1. Inspect all air intake, crankcase vent and turbocharger related hoses/tubes and connections.
2. Inspect the complete exhaust system for damaged, bent or clogged pipes that can cause exhaust system restrictions and excessive back pressure.

Were any problems found?

Yes

- Repair or replace as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Go To 4

4. THROTTLE INLET PRESSURE SENSOR CIRCUIT INSPECTION
1. Turn the ignition off.
2. Disconnect the PCM harness connectors.
3. Disconnect the Throttle Inlet Pressure sensor harness connector.
4. Inspect and test each of the sensor circuits between the sensor connector and PCM harness connectors.

NOTE: Test each circuit for high resistance, a short to ground and a short to voltage.

Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Go To 5

5. SURGE SOLENOID INSPECTION
1. Inspect the Surge Solenoid and any related components for proper operation.
2. Inspect and test each of the Surge solenoid vacuum circuits between the engine and the solenoid.
3. Inspect and test each of the Surge solenoid electrical circuits between the solenoid connector and PCM harness connectors.

NOTE: Test each electrical circuit for high resistance, a short to ground and a short to voltage.

Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Go To 6

6. WASTEGATE AND SOLENOID INSPECTION
1. Inspect the Wastegate Solenoid, linkage and the Wastegate for proper operation.
2. Inspect and test each of the Wastegate solenoid vacuum circuits between the engine, the solenoid and the Wastegate.
3. Inspect and test each of the Wastegate solenoid electrical circuits between the solenoid connector and PCM harness connectors.

NOTE: Test each electrical circuit for high resistance, a short to ground and a short to voltage.

Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.

No

- Repair or replace the Turbocharger.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.