Siemens-Common Rail System – Turbocharger position sensor

fig 1 108 Siemens Common Rail System   Turbocharger position sensor

1 Turbocharger position sensor
2 Turbocharger vacuum unit
3 Variable geometry turbocharger

On some versions with variable geometry turbochargers, a turbocharger position sensor is located at the end of the vacuum unit.

This position sensor further optimizes the boost pressure control. This has a positive effect on exhaust emissions and fuel consumption.

The position sensor is directly connected to the diaphragm in the vacuum unit. When the guide vanes are adjusted (by means of a vacuum, via the boost pressure control solenoid valve, the PCM determines the exact position of the guide vanes via the turbocharger position sensor.

Effects of faults

No substitution strategies are available in the case of a fault. Following the detection of a fault, the boost pressure control switches to open loop control.

The PCM treats this fault in the same manner as a MAP sensor fault and reduces the engine power output (reduction of injected quantity).

Diagnosis

Monitoring of the turbocharger position sensor comprises the following checks:

• Short circuits and open circuits. A check is carried out to see if the signal falls within its limits.
• Logical rise/fall rate of the signal. Intermittent errors (e.g. loose contact for a plug) are determined.
• End stop adjustment for fully opened guide vanes. If too great a deviation is detected during end stop adjustment, it indicates a blockage to the adjustment of a vane.
• Control deviation check. A check is made via the position sensor as to whether the guide vanes adopt the correct position smoothly during adjustment.

Therefore, this is a MIL active component.

Typical malfunction limits:
• Rise/fall rate = 2 V / 10 ms
• Control deviation check > ± 30%

Possible diagnostic trouble codes: P2562, P2564, P2565, P2566.

27. August 2018 by sam
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