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Home >> Mercedes Benz >> 2003 >> CLK 320 (209.365) V6-3.2L (112.955) >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Initial Inspection and Diagnostic Overview >> Initial Inspection (Description and Operation of ME-SFI Systems & Components) >> Distronic (DTR), Function

Distronic (DTR), Function




Distronic (DTR), Function

ENGINES 112, 113, 137, 275, 613, 628 in MODEL 220 as of 1.7.00 up to 31.5.04 with CODE (219a) Distronic (DTR)
ENGINES 113, 137, 275 in MODEL 215 as of 1.7.00 up to 31.5.04 with CODE (219a) Distronic (DTR)
ENGINES 112, 113, 275 in MODEL 230 up to 31.5.04 with CODE (219a) Distronic (DTR)
ENGINES 112, 113, 271, 646, 647, 648 in MODEL 211 up to 31.5.04 with CODE (219a) Distronic (DTR)
ENGINES 112, 113, 271, 612 in MODEL 209 up to 31.5.04 with CODE (219a) Distronic (DTR)
ENGINE 285 in MODEL 240 with CODE (219a) Distronic (DTR)




Shows model 220
A1p13 Multifunction display
B29 DTR radar sensor
E3e4 Left stop lamp
F1/1 Right fuse box
N3/10 ME-SFI [ME] control unit
N10/8 Rear SAM control unit
N15/3 ETC control unit
N28/1 Trailer recognition control unit
N47-5 ESP, SPS and BAS control unit
N63/1 DTR control unit
N72/1 Upper control panel control unit
N73 DI control unit
N80 Steering column module
S40/4 CC with variable speed limiter switch ((USA) (J) S40 CC switch)
S46/8r1 DTR distance potentiometer
S46/8s1 DTR distance warning function switch
X11/4 Data link connector

Tasks
- Maintaining the selected vehicle speed (cruise control function) and also regulating the distance to a vehicle ahead
- Variable speed limiter (VSL), except
- controlling driver information in the instrument cluster and warning signal (distance warning).

Design
The Distronic consists of the following components:
- Distronic control unit
- Distronic radar sensor
- Distronic switch block with distance potentiometer and distance warning function switch
- Variable cruise control switch
- Cruise control switch (USA) (J)
- Displays in instrument cluster and warning signal
- CAN databus.

Function
The cruise control can rarely be used in dense traffic. The driver must either constantly adjust the selected speed or switch off the cruise control.

The Distronic detects the traffic situation ahead of the vehicle by means of the radar sensor located behind the radiator grille.
If the driver's own vehicle approaches another vehicle traveling at a slower speed, the speed of the driver's vehicle is reduced. The Distronic (DTR) control unit calculates the distance required and can activate the following over the CAN:
- - Increase/reduction in the specified engine speed (through ESP control unit)
- Braking (ESP control unit)
- Shifting gears (ETC control unit).

The Distronic can be used from a speed of approx. 30 km/h to 180 km/h or 20 to 110 mph ((USA) 25 to 110 mph).
If no vehicle is driving ahead, the Distronic behaves in the same way as the cruise control.

Note: The Distronic is a convenience system and not a safety system. The driver must himself brake when corresponding traffic situations arise.
The system has a diagnostic capability.

If a vehicle suddenly appears ahead (e.g. as a result of changing lanes), the Distronic attempts to take control. The braking action is, however, limited to approx. 2 meters/s2 (equals approx. 20% of maximum braking power) for safety reasons. If more braking power is required, the driver is warned by means of an intermittent signal (accept signal).

A further audible signal (off signal) sounds if the vehicle speed drops below approx. 30 km/hour ((USA) 25 mph).

If the speed set with the cruise control lever is exceeded by depressing the accelerator pedal, the distance measurement of the Distronic continues to remain active even above 180 km/hour ((USA) 110 mph). The Distronic again controls the vehicle to the speed last set after the accelerator pedal is released.

The driver is able to influence the distance to the vehicle ahead with the distance potentiometer. The setting range equals about 1 to 2 seconds the time distance to the vehicle ahead.

If the Distronic is switched off, the calculation of the distance continues to remain active.

The display in the instrument cluster and the intermittent signal inform the driver if the distance to the vehicle ahead is extremely close or if there is a major difference in speed to the vehicle ahead.

Visual indication (red distance warning lamp in the instrument cluster remains on) is also given if the time distance to the vehicle ahead is less than 0.8 seconds over a time period of more than 3 seconds (except (USA)).

on AMG models the Distronic is switched off at a speed of more than 260 km/hour (160 mph) and a brief warning signal sounds. Consequently, no warning is given if the distance drops below the specified distance. The Distronic cannot be activated again until vehicle speed is less than 260 km/hour.

The variable speed limiter (VSL) is integrated in the Distronic system (except (USA)). It is possible to switch between the functions by pressing the variable cruise control switch (S40/4).

The variable speed limiter is extended as follows in vehicles with Distronic:
- When traveling downhill, the brakes are applied to prevent the vehicle exceeding the set speed.
- Range of use from 10 km/hour up to the maximum vehicle speed.

Further technical data of Distronic:
- Distance measurement range of the radar: 0 to 150 meters
- number of radar beams: 3
- relative speed measurement range for vehicles ahead: -50 to +200 km/hour.
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