Control Module: Description and Operation

GF26.19-P-4009-01R Automated manual transmission control unit, task
- TRANSMISSION 716.6
- with CODE (424) Sequentronic automated manual transmission (SEQ)
- up to model year 08

Component Identification:

Analog output signals
Task of automated manual transmission control unit (N15/6):
^ Recognizes operating states
^ Processing incoming CAN signals
^ Outputs CAN signals
^ Calculates actuating variables
^ Actuation of actuators
^ Saves and outputs diagnostic data
^ Receives analog signals

Only the automated manual transmission control unit (N15/6) is responsible for calculating the shift engagements and clutch engagements from the analog sensor values received of gear recognition, clutch speed, clutch travel, shift desired and pressure value of hydraulic fluid.

The control unit with a 12+2-pin and an 18-pin connector is protected by fuses independently.

To restrict processing loads for signal generation and transmission to a reasonable level, the transmission control system makes use of digital signals that are already available in the vehicle, and calculates some of the required variables from known signals. Examples of this are the computation of the longitudinal and lateral acceleration or the determination of the transmission output speed from the wheel speeds recorded by the ESP and BAS control unit (N47-5) and provided by CAN. So that the incoming signals can be processed by the control unit programs, they are first processed with respect to form and quality with the help of utility programs. The main functions of the SEQ control are stored in the modular structured software in the control unit, in which the individual functions are processed in distinct function blocks. However the mutual dependencies nevertheless lead to a linked function network. The cycle time, in which all function blocks are executed once, is approx. 10 ms.

Input signals (analog):
^ Automated manual transmission pressure sensor (B56)
^ Gear recognition sensor (B56/1)
^ Left door contact switch (S17/3)
^ Clutch travel sensor (B53)
^ Clutch RPM sensor (B52)
^ Power supply of terminal 87 (tml. 87 (tml.15)) from front passenger fuse and relay module (K40/4), fused via fuse 40 (K40/4f40)
^ Power supply of terminal 30 (tml. 30) from rear fuse and relay module (K40/5), fused via fuse 72 (K40/5f72)
^ Sequential floor shift (1)

Output signals (analog):
^ Solenoid valve for clutch of automated manual transmission (Y90)
^ Solenoid valve for brake of automated manual transmission (Y91)
^ Control solenoid valve for automated manual transmission, gear shift 1, 3, 5 (Y92/1)
^ Control solenoid valve for automated manual transmission, gear shift R, 2, 4, 6 (Y92/2)
^ Data link connector (X1 1/4) and system diagnosis control unit (N55)
^ Automated manual transmission hydraulic pump (M46) via the relay for the high pressure/return flow pump (K40/2kF), fused via fuse 2 (K40/2f2)

Via the engine compartment bus (CAN C) there is a connection to the:
^ Instrument cluster (A1)
^ ME-SFI [ME] control unit (/)N3/10
^ ESP, SPS, BAS control unit (N47-5)
^ EIS [EZS] control unit (N73)
^ System diagnosis control unit (N55)

The following information is transmitted from the automated manual transmission control unit (N15/6) via CAN to the:

ME-SFI [ME] control unit (/)N3/10
^ Engine emergency stop
^ Actual gear
^ Target gear
^ Transmission emergency running mode
^ Crawl torque
^ Manual switching mode

Instrument cluster (A1)
^ Current gear
^ Transmission mode
^ Fault/warning messages

ESP, SPS [PML] and BAS control unit ()N47-5
^ Transmission variant
^ Actual gear
^ Target gear

The following information is received from the automated manual transmission control unit (N15/6) via CAN:

Instrument cluster (A1)
^ Driver door open/closed
^ Outside air temperature

ME-SFI [ME] control unit (/)N3/10
^ Pedal value
^ Emergency running
^ Cruise control operating
^ Idle speed
^ Speed limiter active
^ Engine speed limiter active
^ Inertia fuel shutoff
^ Engine torque
^ Oil temperature

Driver-side SAM control unit (N10/10)
^ Wake-up function

ESP, SPS, BAS control unit (N47-5)
^ Wheel speeds and direction of rotation
^ Stop lamp switch
^ Parking brake
^ Signal for ESP control mode

System diagnosis control unit (N55)
^ Diagnosis

EIS [EZS] control unit (N73)
^ Circuit status