The vane position sensor is used by the ECM on Duramax diesels to properly orient the position of the unison ring and corresponding vanes in the Garrett GT3788VA variable geometry turbocharger found on 2004.5 to 2016 model year trucks. A failed or faulty vane position sensor will result in sluggish turbo performance and will typically set a DTC P2563 and accompanying P003A. Additional codes related to turbocharger boost (MAP) may also be present.
The vane position sensor features a plunger that rides on the unison ring armature gear. The gear is concentric such that it acts like a camshaft lobe, and its rotation moves the extruding plunger inwards or outwards of the vane position sensor. Without a proper signal from the vane position sensor the ECM will fail to select the proper vane position via the hydraulically actuated VGT solenoid, resulting in poor turbocharger performance.
After replacing the vane position sensor, the ECM will need to recalibrate or, as it is more commonly referred to, remap. While this can be done manually using certain scan tools, it will also occur perpetually through normal driving. It may take up to several hundred miles of driving for the turbo to remap itself, although it is usually completed in much less time. While the turbo remaps, it may not perform properly and DTCs may be set as it re-calibrates; this is perfectly normal and should be expected. If turbocharger performance does not improve after it has had time to recalibrate, there is likely another turbocharger related issue (VGT solenoid, mechanically stuck VGT system, etc).
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• Locate the vane position sensor atop the turbocharger center section to the driver side of the turbo oil feed line.
• Trace the VPS wire to the electrical connector and disconnect it.
• Snake the electrical connector through the wiring harness and any brackets in its way (it's quite a maze). The wire can also be cut since it is being replaced.
• Remove the heat shield wrap from the vane position sensor by cutting the clamp and peeling it off.
• Remove the VPS from the turbocharger using an appropriate socket (such as Schley SCH12400).
• Ensure that the mating surface is clean of any debris to avoid infiltration into the turbocharger.
• Install the replacement vane position sensor, maneuvering the wire as the socket is rotated as not to kink, break, or entangle the connector/wire.
• Install the included heat shield onto the new vane position sensor. A typically hose clamp can be used as a substitute to the included crimp clamp so that the heat shield can be removed and reinstalled in the future.
• Reinstall the intake resonator and reconnect both negative battery cables.
• Start engine and test for proper operation. If a scantool is being used to recalibrate the sensor, follow the manufacturer's procedures. The system will remap naturally through normally driving, thus this is not required.