How do Dual Clutch Transmissions work? DSG, DCT, PDK, S-tronic. Auto transmission gearbox animation

A dual-clutch transmission (DCT) (sometimes referred to as a twin-clutch transmission) is a type of multi-speed vehicle transmission, that uses two separate clutches for odd and even gear sets. The design is often similar to two separate manual transmissions with their respective clutches contained within one housing, and working as one unit. In car and truck applications, the DCT functions as an automatic transmission, requiring no driver input to change gears.

The fundamental principle of a DCT is that one clutch drives a gear-set for the even-numbered gears, while the other clutch drives the odd-numbered gears. Since the DCT can pre-select an odd gear while the vehicle is being propelled in an even gear (or vice versa), DCTs can shift several times faster than is possible with a manual transmission. By timing the operation of one clutch to engage at the precise moment that the other is disengaging, a DCT can shift gears without interrupting the torque supply to the wheels.

A DCT uses clutch packs (as per a manual transmission), rather than the torque converter used by traditional (hydraulic) automatic transmissions. The DCT clutches are either "wet" or "dry" and are similar to the clutches used in most motorcycles. Wet-clutches are bathed in oil to provide cooling for the clutch surface, therefore wet-clutches are often used in applications with higher torque loads, such as the 1,250 N⋅m (922 lbf⋅ft) engine in the Bugatti Veyron.

Several arrangements for the two clutches are possible, and are outlined below:

Most automotive DCTs use two concentric clutch packs located on the same axis as the flywheel. Therefore, the outer clutch pack has a larger diameter than the inner clutch pack.
Many DCTs for tractors (such as the Fortschritt ZT 320) use a similar arrangement where the clutches are located on the same axis of the flywheel. The difference is that the clutches are at different positions on this axis (i.e. one in front of the other) and the same size as each other. This design is used by the Tremec TR-9070 DCT used by the 2020 Ford Mustang Shelby GT500.
Another design (as used by the Volkswagen DQ200 transmission) arranges two identical-size clutches located side-by-side. This design requires two side-by-side input shafts, which are driven from the crankshaft via gears.

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OBDII CODE VAG CODE DESCRIPTION
P0562 16946 System Voltage too low
P0701 17085 Mechatronic Module defective
P072B 21159 Gear R not selectable
P072C 21153 Gear 1 not selectable
P072D 21154 Gear 2 not selectable
P072E 21155 Gear 3 not selectable
P072F 21156 Gear 4 not selectable
P073A 21157 Gear 5 not selectable
P073B 21158 Gear 6 not selectable
P073C 21159 Gear 7 not selectable
P0746 17130 Pressure Control Solenoid 1 open / short to ground
P0841 10784 Transmission Fluid Pressure Sensor/Switch 1
P0850 17234 Park/Neutral Switch Input Circuit
P0868 17252 Transmission Fluid Pressure Adaptation at Limit
P1604 18012 Internal Control Module
P1624 18032 MIL Request Signal Active (Check TCM for errors too!)
P1701 18109 Transmission Control Unit locked
P1707 18115 Interference in Mechatronic Module
P174C 10742 Valve 1 in Transmission Part 2 malfunction
P175D 10693 Clutch 1 Opens Unintentionally
P175E 10694 Clutch 1 Closes Unintentionally
P176A 10725 Gear Selector 1 Cannot be Regulated
P176B 10726 Gear Selector 2 Cannot be Regulated
P176C 10727 Gear Selector 3 Cannot be Regulated
P176D 10728 Gear Selector 4 Cannot be Regulated
P176E 10694 Clutch 2 Opens Unintentionally
P176F 10696 Clutch 2 Closes Unintentionally
P1775 10047 Hydraulic Pressure Sensor 1 (G193) P limit reached
P177B 10806 Clutch 1 tolerance limit reached
P177C 10778 Clutch 2 tolerance limit reached
P179E 17597 Selector Lever Sensor malfunction
P17BF 6079 Hydraulic Pump play protection
P17D4 10902 Valve 3 in Transmission Part 1 malfunction
P17D5 8960 Valve 3 in Transmission Part 2 malfunction
P17D6 18443 Clutch 1 pressure too high
P17D7 18444 Clutch 2 pressure too high
P17D8 8040 Torque Restriction due to Clutch Temperature
P17E0 17593 Sensor for Gear Actuator 1 malfunction
P1814 18222 Pressure Control Valve 1 (N215) open / short to ground
P1815 18222 Pressure Control Valve 2 (N215) short to +
P1818 18227 Pressure Control Valve 1 (N216) open / short to ground
P1819 18228 Pressure Control Valve 2 (N217) short to +
P1895 10812 Functional Restriction due to Pressure Drop
P1898 18306 Clutch 1 function restriction
P1899 18307 Clutch 2 function restriction
P189A 10817 Clutch 1 clearance too small
P189B 10818 Clutch 2 clearance too small
P189C 10878 Function Restriction due to Insufficient Pressure Build-Up
P2711 19143 Unexpected / Implausible Mechanical Gear Disengagement