Circuit Description

Supercharger boost pressure is regulated to prevent engine and drivetrain damage. When the engine is operating under high boost conditions, the ECM limits boost pressure to 82.7 kPa (12 psi) or less under the following conditions:

• Reverse gear is selected
• Electronic throttle control fault is detected
• An intercooler pump failure is detected
• Engine Coolant Temperature (ECT) is equal to or greater than 125°C (257°F)
• When intake air temperature (IAT) sensor 2 is equal to or greater than 120.5°C (248°F), the ECM commands the boost control solenoid to 62% duty cycle and boost pressure is limited to 145 kPa (7 psi)
• When vehicle speed exceeds 256 km/h (159 mph) in third or fourth gear, boost is limited to a predetermined threshold after 150 seconds

The ECM controls boost pressure by pulse width modulation (PWM) of the supercharger bypass solenoid valve, which is normally open. Under most conditions, the ECM commands the bypass valve solenoid to operate at 99–100% duty cycle, keeping the bypass valve closed and allowing only inlet vacuum from the supercharger plenum to control the position of the bypass valve actuator.

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 engine load increases, engine vacuum decreases, causing the spring to close the bypass valve and allowing boost pressure to increase. When reduced boost pressure is desired, the ECM commands the boost control solenoid to operate between 0 to approximately 62% duty cycle, opening the solenoid valve and allowing boost pressure to enter the bypass valve actuator to counteract the spring tension, recirculating excess boost pressure back into the supercharger inlet.

The ECM monitors the voltage level on the boost control solenoid control circuit.

Diagnostic Fault Information

Conditions for Running the DTC

Conditions for Setting the DTC

DTC Behaviour

Circuit / System Verification

• 1

  
  

  Engine running.

• 2

  
  

  Using a scan tool, command the Supercharger Bypass Solenoid Valve between 0–10%. Verify a click is heard or felt from the Q36 Supercharger Bypass Solenoid Valve.

  No clickRefer to Circuit/System Testing below.

  Click heard or feltContinue to Step 3.
• 3

  
  

  Using a scan tool, command the Supercharger Bypass Solenoid Valve between 0–10%. Verify the following parameters do not display Malfunction:

  • Supercharger Bypass Solenoid Valve Control Circuit High Voltage Test Status
  • Supercharger Bypass Solenoid Valve Control Circuit Open Test Status
  • Supercharger Bypass Solenoid Valve Control Circuit Low Voltage Test Status

  Malfunction displayedRefer to Circuit/System Testing below.

  No malfunctionContinue to Step 4.
• 4

  
  

  Operate the vehicle within the Conditions for Running the DTC. Refer to Freeze Frame / Failure Records data for guidance on replicating the fault conditions.

• 5

  
  

  Verify the DTC does not set.

  DTC setsRefer to Circuit/System Testing below.

  DTC does not setContinue to Step 6.
• 6

  All OK.

Circuit / System Testing

• 1

  
  

  Ignition OFF. Disconnect the harness connector at the Q36 Supercharger Bypass Solenoid Valve. Ignition ON.

• 2

  
  

  Verify a test lamp illuminates between the ignition supply circuit terminal 1 and ground.

  Lamp off - fuse good

  • 2.1Ignition OFF. Remove the test lamp.
  • 2.2Test for less than 2Ω in the ignition circuit end to end.

  ≥ 2ΩRepair the open/high resistance in the circuit.

  < 2ΩVerify the fuse is not open and there is voltage at the fuse.

  Lamp off - fuse open

  An internal short in any component supplied by the fuse may cause the fuse to open and set a DTC when the component is activated.

  • 2.1Ignition OFF. Remove the test lamp.
  • 2.2Test for infinite resistance between the ignition circuit and ground.

  Less than ∞Repair the short to ground on the circuit.

  Infinite resistanceTest all components connected to the ignition voltage circuit for a short and replace as necessary.

  Lamp illuminates Continue to Step 3.
• 3

  
  

  Verify a test lamp does NOT illuminate between control circuit terminal 2 and ignition circuit terminal 1.

  Lamp illuminates

  • 3.1Ignition OFF. Disconnect the harness connector at the K20 Engine Control Module. Remove the test lamp.
  • 3.2Test for infinite resistance between the control circuit and ground.

  Less than ∞Repair the short to ground on the circuit.

  Infinite resistanceReplace the K20 Engine Control Module.

  Lamp does not illuminate Remove the test lamp. Continue to Step 4.
• 4

  
  

  Remove the test lamp.

• 5

  
  

  Using a scan tool, verify the Supercharger Bypass Solenoid Valve Control Circuit High Voltage Test Status parameter is OK when commanding the Supercharger Bypass Solenoid Valve to 10%.

  Not OK

  • 5.1Ignition OFF. Disconnect the harness connector at the K20 Engine Control Module. Ignition ON.
  • 5.2Test for less than 1V between the control circuit and ground.

  ≥ 1VRepair the short to voltage on the circuit.

  < 1VReplace the K20 Engine Control Module.

  OK displayed Continue to Step 6.
• 6

  
  

  Install a 3A fused jumper wire between control circuit terminal 2 and ignition circuit terminal 1.

• 7

  
  

  Using a scan tool, verify the Supercharger Bypass Solenoid Valve Control Circuit High Voltage Test Status parameter shows Malfunction when commanding the Supercharger Bypass Solenoid Valve to 10%.

  Malfunction not displayed

  • 7.1Ignition OFF. Disconnect the harness connector at the K20 Engine Control Module.
  • 7.2Test for less than 2Ω in the control circuit end to end.

  ≥ 2ΩRepair the open/high resistance in the circuit.

  < 2ΩReplace the K20 Engine Control Module.

  Malfunction displayed Continue to Step 8.
• 8

  Test or replace the Q36 Supercharger Bypass Solenoid Valve.

Component Testing

Repair Instructions

Perform a diagnostic repair verification after completing the repair.