P0237

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) operates a solenoid to control boost. This solenoid is normally open. By providing a ground path the PCM energizes the solenoid which allows vacuum to pass to the wastegate valve. During normal operation, the PCM compares the wastegate duty cycle signal with the boost signal and makes corrections in the duty cycle accordingly.

CONDITIONS FOR RUNNING THE DTC
^ The PCM performs this Diagnostic Trouble Code (DTC) diagnostic continuously.
^ The ignition is in the ON position.

CONDITIONS FOR SETTING THE DTC
^ The boost pressure is less than 40 kPa.
^ All diagnostic conditions are met for 10 seconds.

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.
^ Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS
Very little boost can be attained by revving the engine in neutral. If the boost sensor signal circuit is open or shorted to ground, the boost solenoid will show a zero duty cycle.

An intermittent may be caused by the following conditions:
^ Poor connections
^ Rubbed through wire insulation
^ Broken wire inside the insulation

TEST DESCRIPTION

Steps 1-3:

Steps 4-14:

The numbers below refer to the step numbers on the diagnostic table.
2. This step will determine if DTC P0237 is the result of a hard failure or an intermittent condition.
3. This step simulates conditions for a DTC P0237. If the PCM recognizes the change, the PCM and signal circuit are OK.
9. In this step, components that share the 5-volt reference can cause the reference voltage to be shorted to ground. This can be checked by disconnecting each component that shares the 5-volt reference one at a time, including the PCM, while checking for continuity on that circuit to chassis ground.