Circuit Description
The supercharger is designed to pump more air than the engine would normally use. This excess air creates a boost pressure in the intake manifold. Maximum engine boost is 83 kPa (12 psi). Because the supercharger is a positive displacement pump and is directly driven from the engine drive belt system, boost pressure is available at all driving conditions.
When boost is not desired, such as during idle and light throttle cruising, the excess air that the supercharger is producing is routed through the bypass passage between the intake manifold and the supercharger inlet. This bypass circuit is regulated by a bypass valve which is similar to a throttle plate. The bypass valve is controlled by a vacuum actuator which is connected to the vacuum signal between the throttle and the supercharger inlet. Spring force from the actuator holds the valve closed to create boost, and vacuum pulls the valve open when the throttle closes to decrease boost. The open bypass valve reduces pumping loss thereby increasing fuel efficiency.
The solenoid valve attached to the bypass actuator is an electronically controlled, three-way valve. This valve, controlled by the powertrain control module (PCM), determines whether pressure from the manifold is routed to the bypass actuator or closed off. The valve allows pressure from the manifold to open the bypass valve and regulate boost pressure during specific driving conditions.
The PCM controls boost pressure by using the boost control solenoid. The boost control solenoid is a normally open valve. Under most conditions, the PCM commands the boost control solenoid to operate at a 99-100 percent duty cycle. This keeps the solenoid valve closed and allows only inlet vacuum from the supercharger plenum to the bypass valve actuator to control the position of the bypass valve. At idle, engine vacuum is applied to the upper side of the bypass valve actuator, counteracting spring tension to hold the bypass valve open. When the engine load is increased, the engine vacuum is decreased, causing the spring in the bypass valve to overcome the diminishing applied vacuum, closing the bypass valve and allowing the boost pressure to increase. When reduced boost pressure is desired, the PCM commands the boost control solenoid to operate at a 0-98 percent duty cycle. This opens the solenoid valve and allows boost pressure to enter the bypass valve actuator at the lower side to counteract the spring tension, opening the bypass valve, and recirculating excess boost pressure back into the supercharger inlet.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2261 Supercharger Bypass Valve Stuck
Conditions for Running the DTC
| • | DTCs P0096, P0097, P0098, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0116, P0117, P0118, P0125, P0128, P0335, P0336, P1183, P1184 are not set. |
| • | The engine speed is between 400-8,192 RPM. |
| • | The IAT Sensor parameter is between -7°C and +125°C (+19° and 257°F). |
| • | The ECT Sensor parameter is between 70°C and +125°C (+158° and 257°F). |
| • | This DTC runs continuously within the enabling conditions. |
Conditions for Setting the DTC
The PCM detects that the supercharger bypass valve is stuck shut.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Step | Action | Values | Yes | No | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Boost Control System Description: Boost Control System Description | ||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||||||||||
2 |
Important: This diagnostic assumes that the engine is in satisfactory mechanical condition and able to provide sufficient vacuum to operate the boost control system.
Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 3 | ||||||||||||||||||
3 |
Is the vacuum at the specified value? | 0 in Hg | Go to Step 4 | Go to Step 10 | ||||||||||||||||||
4 |
Is the vacuum more than the specified value? | 15 in Hg | Go to Step 5 | Go to Step 8 | ||||||||||||||||||
5 |
Is the vacuum more than the specified value? | 15 in Hg | Go to Step 6 | Go to Step 12 | ||||||||||||||||||
6 |
Does the bypass valve actuator retract? | 18 in Hg | Go to Step 7 | Go to Step 11 | ||||||||||||||||||
7 |
Does the bypass valve actuator extend? | 20 in Hg | System OK | Go to Step 11 | ||||||||||||||||||
8 |
Is the vacuum more than the specified value? | 15 in Hg | Go to Step 14 | Go to Step 9 | ||||||||||||||||||
9 |
Is the vacuum more than the specified value? | 15 in Hg | Go to Step 10 | Go to Step 13 | ||||||||||||||||||
10 | Replace the boost control solenoid. Refer to Boost Control Solenoid Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||||||||||||||
11 | Replace the bypass valve actuator. Refer to Supercharger Bypass Valve Actuator Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- | ||||||||||||||||||
12 | Repair the inlet vacuum signal hose or the port for a restriction or blockage. Did you complete the repair? | -- | Go to Step 15 | -- | ||||||||||||||||||
13 | Repair the boost source hose or the port for a restriction or blockage. Did you complete the repair? | -- | Go to Step 15 | -- | ||||||||||||||||||
14 | Repair the boost signal hose or the port for a restriction or blockage. Did you complete the repair? | -- | Go to Step 15 | -- | ||||||||||||||||||
15 |
Did you verify the repair? | -- | Go to Step 16 | Go to Step 2 | ||||||||||||||||||
16 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||||||||||||
