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Home >> Audi >> 2016 >> S5 Prestige, 2D Convertible >> Repair and Diagnosis >> External Pages >> Different car >> Section 1085 (Four-Wheel Drive Systems) >> Diagnosis And Testing >> Four-Wheel Drive Systems - Vehicles With: 2-Speed Torque On Demand Transfer Case >> Pinpoint Tests >> Pinpoint Test G : Shift Motor - Electrical Or Mechanical Fault >> Notes

Pinpoint Test G : Shift Motor - Electrical Or Mechanical Fault: Notes

WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Wiring Diagram Four Wheel Drive Systems for schematic and connector information.

Normal Operation 

The electric shift motor is mounted externally to the transfer case. It drives a rotary cam which moves the range and mode forks within the transfer case. The shift motor moves during shifts in to and out of 4L, and to Neutral. It does not move during the shift between 2H and 4A or 4A to 4H. TCCM directly controls the electric shift motor and can reverse motor polarity to reverse rotary cam/shift fork direction. The message center may display "Shift in Progress" while the shift motor is operating. The shift motor sense plate, an integral part of the shift motor assembly, informs the TCCM of the transfer case position. The sense plates are a set of 4 contacts that are opened and closed to represent each valid transfer case shift motor position.

TRANSFER CASE SHIFT MOTOR STATUS 

MSS Position  Contact Plate Position 
Position PLATE_A  PLATE_B  PLATE_C  PLATE_D 
2H Mode CLOSED OPEN CLOSED CLOSED
4A Mode CLOSED OPEN CLOSED CLOSED
4H Mode CLOSED OPEN CLOSED CLOSED
4L Mode OPEN CLOSED OPEN CLOSED
Neutral CLOSED CLOSED OPEN OPEN

DTC Fault Trigger Conditions 

DTC Description Fault Trigger Conditions
P1839:00 Transfer Case Shift Motor Open Circuit: No Sub Type Information This DTC sets when the TCCM detects battery voltage less than 9 volts for 5 seconds or more at TCCM.
P1840:00 Transfer Case Shift Motor Short Circuit To Battery: No Sub Type Information This DTC sets when TCCM detects a short to voltage. Shift motor moves are prevented when this DTC is set.
P1841:00 Transfer Case Shift Motor Short Circuit To Ground: No Sub Type Information This DTC sets when TCCM detects a short to ground. Shift motor moves are prevented when this DTC is set.
P1849:00 Transfer Case Contact Plate 'A' Short Circuit To Ground: No Sub Type Information This DTC sets when TCCM detects a short to ground. Shift motor moves are prevented when this DTC is set. The TCCM cannot complete mode change if a change in shift motor position is required.
P184B:00 Transfer Case Unable to Transition Between 4H and 4L: No Sub Type Information This DTC sets when target shift motor position is not reached after the maximum number of allowed blocked shift retries for 4H to 4L. Requested shift motor position is not reached.
P1853:00 Transfer Case Contact Plate 'B' Short Circuit to Ground: No Sub Type Information This DTC sets when TCCM detects a short to ground. Shift motor moves are prevented when this DTC is set. The TCCM cannot complete mode change if a change in shift motor position is required.
P1857:00 Transfer Case Contact Plate 'C' Short Circuit to Ground: No Sub Type Information This DTC sets when TCCM detects a short to ground. Shift motor moves are prevented when this DTC is set. The TCCM cannot complete mode change if a change in shift motor position is required.
P1861:00 Transfer Case Contact Plate 'D' Short Circuit to Ground: No Sub Type Information This DTC sets when TCCM detects a short to ground. Shift motor moves are prevented when this DTC is set. The TCCM cannot complete mode change if a change in shift motor position is required.
P1867:00 Transfer Case Contact Plate General Circuit Failure: No Sub Type Information This DTC sets when an invalid shift motor position is detected during selection of a new 4WD mode or during a motor movement. If the shift motor is not moving, shift motor movement is prevented. If the shift motor is moving when this DTC sets, the shift motor moves to the high-side mechanical stop.
P1891:00 Transfer Case Contact Plate Ground Return Open Circuit: No Sub Type Information This DTC sets when TCCM detects a short to ground, a short to voltage or open circuit. The TCCM cannot complete mode change if a change in shift motor position is required.

Possible Sources 

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