Drive control (FR) function

W30.35-1052-09

1 Vehicle CAN bus

2 Special equipment CAN bus

3 Engine CAN bus

4 Vehicle CAN data bus to star point in instrument (only if FR and MR/PLD are fitted individually)

5 Speed signal (v-signal) from tachographs

6 Switch MSS (only for code (MJ6) engine start/stop system)

7 Fault readout on display of the flame starting system (FLA)

8 Fault readout on display of the drive regulation (FR)

9 Engine oil level and engine oil pressure check control indicator lamp

10 Coolant level check control indicator lamp

11 Air filter monitoring check control indicator lamp

12 Charge indicator lamp

13 Permanent brake indicator lamp

14 FR and MR fault lamp (EDC= electronic diesel control)

S4 Stop lamp switch

S9 Neutral position switch

S85 Clutch pedal switch 1

S89 Clutch pedal switch 2

X13 Diagnostic socket

Y63 High/low splitter group solenoid valve

Y64 Shift force assistance solenoid valve
(transmission 715.320)

Z1 CAN star point cab dash support

Z2.1 CAN star point, cab rear wall

A Cab

B Chassis

a) Electronic body manufacturer

b) Flame starting system

c) Electronic components on the engine

d) Only if transmission 715.320 fitted

e) Stop lamp

* Special equipment (SA)

15 Parking brake indicator lamp

16 Indicator lamp for the engine start/stop system

17 Indicator lamp for flame starting system

18 Engine brake/constant throttle solenoid valve

A3 Vehicle engine control (FMR) control unit

A6 MR/PLD control unit

A7 Base module

B1 Foot throttle actuator

B3 Countershaft rpm sensor

B4 Outside temperature sensor

B5 Parking brake switch

B6 Coolant level switch

B7 Air filter monitoring sensor/

switch

G2 Alternator

H5 PTO 1 indicator lamp

H6 PTO 2 indicator lamp

P2 Instrument

S2 Engine control/permanent brake operating lever

S3 Splitter switch

General information

The drive control unit (FR) is, like the engine control unit (MR), an independent, electronic system which provides the interface between the chassis and the drive train.

It regulates, controls and monitors all vehicle-specific functions which are required while driving, whereby the main task is to calculate the torque specified and required by the driver from the engine and to transmit this to the engine regulation unit (MR).

The central control unit is the drive control (FR) control unit (A3) which is networked over the vehicle CAN bus (1) with various equipment including
the instrument (P2) and over the engine CAN bus (3) with the MR/PLD control unit (A6).

1 Base functions of the drive control (FR)

1.1 Calculation and transmission of the specified engine torque.
The specified engine torque is a purely calculated value which arises from driving commands made by the driver.
This value is primarily dependent on the position of the gas pedal which is determined by the drive control (FR) control unit (A3) in cooperation with the foot throttle actuator (B1).

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 The drive control (FR) can limit the specified engine torque to maintain the legally prescribed maximum speed or during a regulating intervention of the Antilocking System (ABS) or the Acceleration Slip Regulation (ASR).

The drive control (FR) calculates the specified engine torque and then sends this over the engine CAN bus (3) to the engine control (MR).

1.2. Controlling constant throttles and the engine braking flap.
There is either a pneumatic or an hydraulic constant throttle installed depending on the engine version and vehicle equipment. Activation of the respective solenoid valves, which either pass on oil or compressed air to the respective constant throttles, takes place either by the drive control (FR) control unit (A3) or the MR/PLD control unit (A6).
Control of the engine braking flap does, however, always take place over the drive control (FR).

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1.3 Determination and provision of the vehicle speed.
The drive control (FR) determines the current vehicle speed based on various input values which a number of factors depend upon, including limitation of the specified engine torque, and makes this available to the other systems via the vehicle CAN bus (1).

1.4 Preregulation of the generator and monitoring of the charge current.
Preregulation of the generator does not take place via the charging indicator lamp but instead by means of a circuit in the drive control (FR) control unit (A3).
The drive control (FR) control unit (A3) also monitors the charge current of the alternator (G2) and requests indication of the symbol for charge control in the instrument via the vehicle CAN bus (1) (P2) if the charge current is either too low or missing altogether.

2 Additional functions of the drive regulation (FR)

2.1 Vehicles with the code (MD9) Cruise control.
Speed regulation by means of the cruise control and Temposet is integrated into the drive control (FR) as a software function on vehicles with the code (MD9) Cruise control.

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Regulation of the desired vehicle speed is achieved by means of appropriate adjustment of the specified engine torque.

2.2 Vehicles fitted with an auxiliary drive.
Working speed control with variable and/or fixed speed for a number of auxiliary drives is achievable over the drive control (FR).

2.3 Vehicles fitted with transmission 715.320.
The following additional transmission control functions are executed on vehicles fitted with transmission 715.320:

 Splitter control

 Overspeed warning

 Shift force assist

2.4 Vehicles with the code (MZ4) Turbobrake.
Activation of the solenoid valve which leads compressed air to the working cylinder of the turbobrake is achieved by the drive control (FR) control unit (A3) via the output used on vehicles without the code (MZ4) Turbobrake for activating the solenoid valve for the pneumatic constant throttle.

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3 Diagnostic functions of the drive control (FR).
When the drive control (FR) is installed, the majority of installed components are monitored by the drive control (FR) control unit (A3). Components which cannot be monitored (switches etc.) can be checked in full using measurement and binary values. In certain cases, connected components can be measured in test mode (resistance measurement) or a test actuation performed (active test).

4 Area of application functions offered by the drive control (FR).
Extensive capabilities for setting parameters are essential in order to deploy the control units for drive control (FR) for all vehicle types from the parts management point of view.
Outputs and inputs can be assigned with different functions and fault recognition can be switched off or on at various outputs and inputs in order to enable the drive control (FR) control unit to be adapted to individual equipment versions.