DRIVELINE FAMILY

Hyundai Transys 7DCT Transmission / Driveline Family

7DCT family transmission type, ratio/speed class, drivetrain layout and diagnostic approach.

QUICK TECHNICAL ANSWERS

What concrete information can you get from this page?

Verified application example: Hyundai Europe · i20 III / 7DCT technology references · i20 1.0 T-GDI 48V example · 1.0 T-GDI mild hybrid example · Hyundai 7DCT

VERIFIED FACTModel / system fact

Hyundai describes its 7DCT as a seven-speed dual-clutch automated transmission architecture.

FAULT SEPARATIONWhen a symptom appears

For a shift fault verify actual ratio from input/output speed first, then separate clutch slip/temperature from actuator command.

FIRST MEASUREMENTBefore replacing parts

Before clearing DTCs record input/output speed, commanded/actual gear, clutch slip/temperature, actuator state and engine torque request.

Primary source: Hyundai – How dual-clutch transmission works

Technical identity

Manufacturer group: Hyundai Transys
Transmission family: 7DCT
Type: dry dual clutch
Speeds / ratio: 7
Drivetrain layout: FWD/AWD

What to separate first in diagnosis

Test electronic control, hydraulic pressure, clutch/converter and mechanical driveline behaviour separately.
Temperature and fluid level/condition can directly affect pressure regulation and adaptation behaviour.
Verify software, mechatronic and ratio variants within the same family by exact application/part identity.

TRANSMISSION DIAGNOSTIC FLOW

Measurement sequence

Confirm exact transmission code and software/application variant.
Verify fluid level, condition and temperature.
Capture input/output speeds and actual ratio.
Test electronic command, hydraulic pressure and mechanical clutch separately.
Verify shift/adaptation result under load.

Source-verified powertrain relationships

The relationships below come only from existing curated relation records; they are not exact vehicle/model fitment claims.

OEM EVIDENCE DOSSIER

Verified technical facts and application boundary

Hyundai describes its 7DCT as a seven-speed dual-clutch automated transmission architecture. [S1]
In the i20 III 1.0 T-GDI 48 V application, 7DCT operates as part of mild-hybrid engine/BSG torque coordination. [S1] [S2]
Because the dual-clutch layout has two clutches and alternating power paths, clutch slip/temperature and input/output speeds must be monitored separately. [S2]

Verified application matches

The matches below are published only within the stated market, model-year and evidence scope. Fitment is not extrapolated to uncited variants.

System architecture and component relationships

Split transmission control into clutch 1/2, input shafts, selector/actuator, oil/thermal state and TCU-CAN torque coordination.
Time-align commanded/actual gear, input/output speed, clutch slip/temperature and engine torque-reduction command.
If an electric motor is integrated into the transmission, correlate motor torque request, inverter voltage/temperature and clutch transition through the same shift.

DTC / SPN-FMI / symptom discrimination map

For a shift fault verify actual ratio from input/output speed first, then separate clutch slip/temperature from actuator command.
Where electric torque assistance is present, correlate engine/e-motor torque coordination with clutch state through the shift event.
If network or low-voltage DTCs accompany the complaint, rule out supply/CAN events before condemning mechatronic hardware.

Measurement and diagnostic strategy

Before clearing DTCs record input/output speed, commanded/actual gear, clutch slip/temperature, actuator state and engine torque request.
Independently verify supply voltage and CAN integrity before condemning mechatronic hardware; use only OEM test ports/procedures for hydraulic/oil pressure.
After repair repeat the same cold/hot shifts and compare slip and torque coordination.

Exact pinouts, torque values, pressure thresholds or service limits are published only when explicitly verified by the applicable OEM service source.

Evidence provenance and primary sources

Hyundai – How dual-clutch transmission works · OEM-primary · 2026-08-17
Hyundai Europe – i20 48V / 7DCT · OEM-primary · 2026-08-17

DRIVELINE DIAGNOSTIC DEPTH

Mechanical-hydraulic-electronic architecture

For DCT/DSG, TCU-mechatronics, K1/K2 clutches, actuator/line pressure and input/output speeds are evaluated together.
In AWD/4x4, tire circumference, transfer/differential, wheel speeds and torque-distribution request are kept as separate mechanical/electronic evidence.

Driveline live-data package

Freeze frame: first/last fault time, RPM, load, vehicle speed, system voltage, core temperatures and companion DTCs.
Driveline: input/output speeds, commanded/actual ratio, clutch/TCC slip, fluid temperature, actuator/solenoid command and adaptations.
Chassis/traction: four wheel speeds, steering angle, yaw/acceleration and AWD torque request/feedback on the same time base.

Driveline measurement chain

1) Match vehicle/generation/market/powertrain/driveline identity to the source record; family name alone is not fitment evidence.
2) Preserve freeze frame and companion DTCs before clearing; make the first-fault condition reproducible.
3) Verify power/ground and network communication under load; do not decide from key-on static measurement alone.
5) Compare electronic command → hydraulic/actuator response → mechanical slip/ratio result at the same temperature and load.
6) After repair, recreate the same load/temperature and verify DTC state, live-data deviation and user symptom together.

Fluid type/level temperature, pressure thresholds, adaptation limits and part codes are not asserted without application-specific OEM evidence.

Driveline root-cause split

For DCT harshness/slip, separate TCU command from clutch slip and actuator/hydraulic response; adaptation result alone does not prove mechanical wear.
For AWD binding/warning complaints, exclude tire-circumference or wheel-speed mismatch before condemning transfer/differential hardware.

Sources & freshness

Exact technical values, prices and failure rates are not invented without verified vehicle/manufacturer evidence.

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