Circuit Description
The turbocharger wastegate is a vacuum actuated valve used to control the exhaust gas heat sent to the turbo. The wastegate pulse width modulated solenoid meters the vacuum level at the wastegate valve actuator as commanded by the PCM. When the PCM is commanding the wastegate solenoid ON, the voltage potential of the circuit will be low (near 0 volts). When the PCM is commanding the wastegate solenoid OFF, the voltage potential of the circuit will be high (near battery voltage). The primary function of the PCM in this circuit is to supply the ground for the wastegate solenoid.
Conditions for Running the DTC
The ignition switch in the ON position.
Conditions for Setting the DTC
| • | The voltage on the wastegate solenoid control circuit is high (near battery voltage) when the wastegate solenoid is requested ON. |
| or |
| • | The voltage on the wastegate solenoid control circuit is low (near 0 volts) when the wastegate solenoid requested OFF. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive drive trip the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Failure Records store this information. If the diagnostic reports a failure on the second consecutive drive trip, the Freeze Frame records the operating conditions at the time of failure and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL off after three consecutive trips without a fault condition. |
| • | A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures |
| • | The use of a scan tool. |
Diagnostic Aids
This diagnostic will set when the control circuit does not follow the PCM command (when the solenoid is requested ON voltage will drop, when the solenoid is OFF ignition voltage will be present). The scan tool has a 5 second ON time abort. The wastegate solenoid can be commanded ON for as many times as needed, in 5 second intervals. It's possible DTC P0236 may set along with DTC P1656. This diagnostic can be checked during key up. The engine will not respond to scan tool commands at idle (engine unable to achieve boost pressures greater than BARO at idle) or at any engine speed greater than idle (PCM control aborts to prevent engine damage).
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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Checks that both the ON and OFF states are commanded. Repeat the commands as many times as necessary.
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This check can detect a partially shorted coil which would cause excessive current flow. Leaving the circuit energized for 2 minutes allows the coil to warm up. When warm, the coil may open (amps drop to zero), or short (amp draw greater than 0.75A).
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If no trouble is found in the control circuit or the connection at the PCM, the PCM may be malfunctioning. However, this is an extremely unlikely failure.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing any DTCs, use the scan tool Capture Info to save freeze frame and failure records for reference, as the Scan tool loses data when using the Clear Info function. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Does the solenoid turn ON and OFF (audible click) with each command? | -- | |||
Is the current draw less than the specified value, but not zero? | 0.75 A | |||
4 |
Does the DMM display infinite resistance? | -- | ||
5 |
Does the test light turn ON and OFF with each command? | -- | ||
6 |
Is the test light ON? | -- | ||
7 |
Does the solenoid operate (audible click)? | -- | ||
8 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored refer to the applicable DTC table(s) first. Are any additional DTCs stored? | -- | Go to the Applicable DTC Table | Go to Diagnostic Aids |
9 | Check for a proper connection at the wastegate solenoid and replace any terminals as necessary. Did any terminals require replacement? | -- | ||
10 | Repair the wastegate solenoid control circuit. Is the action complete? | -- | -- | |
11 | Check for a proper connection at the PCM wastegate solenoid control circuit. Was a problem found? | -- | ||
12 | Repair the open in the ignition feed circuit. Is the action complete? | -- | -- | |
13 | Replace the wastegate solenoid. Refer to Wastegate Solenoid Replacement . Is the action complete? | -- | -- | |
Replace the PCM. Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
15 |
Does the scan tool indicate the diagnostic Passed? | -- | ||
16 | Does the scan tool display any additional undiagnosed DTCs? | -- | Go to the Applicable DTC Table | System OK |
