Circuit Description
The turbocharger wastegate is a vacuum actuated valve which is used in order to control the exhaust gas heat which is 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 the battery volts). The primary function of the PCM in this circuit is to supply the ground for the wastegate solenoid.
Conditions for Setting the DTC
| • | The PCM requested the Wastegate solenoid ON. |
| • | The voltage on the Wastegate solenoid control circuit is high (near the battery volts). |
| • | Two consecutive faults have been detected. |
| • | The conditions were met for 2 seconds. |
or
| • | The PCM requested the Wastegate solenoid OFF. |
| • | The voltage on the Wastegate solenoid control circuit is low (near 0 volts). |
| • | Two consecutive faults have been detected. |
| • | The conditions met for 2 seconds. |
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 will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from the start up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle). |
| • | Use of a Scan Tool will clear the DTC codes. |
Diagnostic Aids
This diagnostic will set when the control circuit does not follow the PCM command (when the solenoid is requested ON, the voltage will drop; when the solenoid is OFF, the 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. DTC P0236 may possibly set along with DTC P1656. This diagnostic can be checked during key up. The engine will not respond to the scan tool commands at the idle (the engine is unable to achieve the boost pressures that are greater than BARO at idle) or at any engine speed which is greater than the idle (the PCM control abort in order to prevent the engine damage).
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
-
Be sure that both the ON and OFF states are commanded. Repeat the commands as many times as necessary. This step will determine if this DTC is a current or an intermittent.
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This check can detect a partially shorted coil which would cause an excessive current flow. Leaving the circuit energized for two minutes allows the coil to warm up. When warm, the coil may open (Amps drop to zero), or short (an amp drawn greater than 0.75A).
-
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 the DTCs, use the Scan Tool Capture Info in order to record the Freeze Frame and the failure records for reference, as the data will be lost when the Clear Info function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
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 an 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? | -- | ||
8 | The DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If any additional DTCs were stored, refer to the applicable DTC tables first. Are there any additional DTCs stored? | -- | Go to the applicable DTC table | Go to Diagnostic Aids |
9 | Check for a poor connection at the boost solenoid and replace the terminal if necessary. Refer to Wiring Repairs in Wiring Systems. Did the terminal require replacement? | -- | ||
10 | Repair the Wastegate solenoid control circuit. Is the action complete? | -- | -- | |
11 | Check for a poor connection at the PCM, Wastegate 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 PCM Replacement/Programming . Is the action complete? | -- | -- | ||
15 |
Does the Scan Tool indicate that this diagnostic Passed? | -- | ||
16 | Use the Scan Tool in order to select Capture Info, Review Info. Are there any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
