GF42.40-P-0005-03A Acceleration slip regulation (ASR V/ETS), location of electrical/electronic components Typ 129  

A1e17 ABS MIL
B24/2 Lateral acceleration sensor (129.076)
K20/1 High-pressure/return pump relay
A7/3 ASR or ETS hydraulic unit
L6/1, L6/2 Left and right front axle VSS sensor
L6/3, L6/4 Left and right rear axle VSS sensor
N16/1 Base module
S9/1 Stop lamp switch (4-pin)
S12 Parking brake switch
X11/4 Data link connector (DTC readout)
Y61 Master brake cylinder switchover valve (129.076)
On ASR only
A1e21 ASR warning lamp
A1e22 ASR MIL (vehicles without BAS only)
A1e48 BAS/ASR malfunction indicator lamp (vehicles with BAS only)
N47-1 ASR control module
S76/5 ASR OFF switch
 
    P42.40-0292-06

On ETS only
A1e35 ETS MIL
A1e36 ETS warning lamp
N47-2 ETS control module 		       

GF42.40-P-4000A

GF42.40-P-4000A Location/purpose/design/function of ASR V/ETS hydraulic unit 6.12.94

MODEL  129, 140, 202 as of 1.6.94,
  170, 208, 210 / (except , 210.08 /28)
  with CODE (471a) Acceleration slip regulation (ASR)
  with CODE (212a) Electronic traction support (ETS)


   
P42.40-0206-01   P42.35-0212-01   P42.35-0201-01

Bosch up to 05/97   Bosch as of 06/97   Teves

A7/3 ASR V/ETS hydraulic unit
m1 High-pressure pump/return pump
H To rear axle tandem master brake cylinder
V To front axle tandem master brake cylinder		   HL to left rear brake caliper
HR to right rear brake caliper
VL to left front brake caliper
VR to right front brake caliper
  Location in left of engine compartment  
  Task The ASR V/ETS hydraulic unit (A7/3) performs the control functions of the brake moment control circuit.  
Design of ASR V/ETS hydraulic unit   GF42.40-P-4000-01A
Function of ASR V/ETS hydraulic unit   GF42.40-P-4000-02A

GF42.40-P-4000-01A

GF42.40-P-4000-01A Design ASR V/ETS hydraulic unit Models 129, 140, 170, 202, 208, 210 (except 210.08/28)

   
    P42.40-0289-06

a Teves version
4 Brake unit
5a Right front wheel brake
5b Left front wheel brake
6a Right rear wheel brake
6b Left rear wheel brake
7 Check valve
9 Return pump check valve
10 Silencer
11 Low pressure accumulator
12 Diaphragm discharge silencer
15 Intake valve (Teves only)


  A7/3 ASR/ETS hydraulic unit
A7/3m1 High-pressure/return pump
p1 Self-priming high-pressure/return pump
p2 Return pump
A7/3y5 Switchover/solenoid valve
A7/3y6 Left front axle solenoid valve (hold)
A7/3y7 Left front axle solenoid valve (release)
A7/3y8 Right front axle solenoid valve (hold)
A7/3y9 Right front axle solenoid valve (release)
A7/3y10 Left rear axle solenoid valve (hold)
A7/3y11 Left rear axle solenoid valve (release)
A7/3y12 Right rear axle solenoid valve (hold)
A7/3y13 Right rear axle solenoid valve (release)
A7/3y15 ntake solenoid valve (Bosch only)

GF42.40-P-4000-02A

GF42.40-P-4000-02A ASR V/ETS hydraulic unit, function Model 129, 140, 170, 202, 208, 210 except 120.08/28

   
    P42.40-0289-06

All switching components of the ABS and ASR or ETS systems are combined in the ASR/ETS hydraulic unit (A7/3).
A 2/2-way valve for build-up/hold pressure or hold/release pressure functions is used on each wheel for control. The self-priming high pressure/return pump (p1), integrated in the hydraulic unit (A7/3), supplies pressure to the ASR or ETS. An integrated return pump (p2) is also used to return brake fluid for ABS control. The inlet pipes of the self-priming high pressure/return pump (p1) contain the inlet solenoid valve (y15) in the Bosch model and inlet valve (15) in the Teves model.
  The inlet solenoid valve (y15, Bosch model) is opened once pressures of 60 bar are reached in the rear axle brake calipers during the ASR or ETS pressure build-up phase. It stays open for the time it takes to actuate the solenoid valves (y10 and y12). When pressures of > 60 bar are reached in one of the rear axle brake calipers during ASR or ETS control, the inlet solenoid valve (y15) remains open continuously. In the Teves model, the inlet valve (15) always remains open apart from when the valve is pressurized via the brake pedal with a pressure of > 0.6 bar.

During ASR control, the switchover solenoid valve (y5) locks the rear axle circuit to the brake master cylinder. The valve is also designed to function as a pressure relief valve and opens at approx. 160 bar. The noise of the pulsating brake fluid is reduced by a diaphragm discharge damper (12) and returned to the brake master cylinder.
  A muffler (10) is fitted for each brake circuit to reduce delivery noise.
During the ABS/ETS/ASR pressure reduction phase the brake fluid flows back to the high-pressure/return pump via the accumulator.


GF42.35-P-0001A

GF42.35-P-0001A Electronic Traction Support (ETS) function 4.9.96

MODEL  129, 140, 202 as of 1.6.94,
  170, 210 with CODE (212a) Electronic traction support (ETS)
ETS tasks/benefit Model 129, 140, 170, 202, 210 except model 210.08/28 GF42.35-P-0001-02A
ETS tasks/benefit Model 210.08/28 GF42.35-P-0001-02B
ETS driver information   GF42.35-P-0001-03A
ETS function survey Model 129, 140, 170, 202, 210 except model 210.08/28 GF42.35-P-0001-04A
ETS function survey Model 210.08/28 GF42.35-P-0001-04B
ASR V/ETS, location of hydraulic components   GF42.40-P-0005-02A
ASR V/ETS, location of electric/electronic components Model 129 GF42.40-P-0005-03A
    Model 140 GF42.40-P-0005-03B
    Model 170 GF42.40-P-0005-03C
    Model 202 GF42.40-P-0005-03D
    Model 210 GF42.40-P-0005-03E
ASR V/ETS notes on towing, test and repair work Model 129, 140, 170, 202, 210 except model 210.08/28 GF42.40-P-0005-01A
ETS, notes on towing, test and repair work Model 210.08/28 GF42.35-P-0001-05A
ETS brake moment control circuit   GF42.35-P-2000A

GF42.35-P-0001-02A

GF42.35-P-0001-02A Electronic traction system (ETS), task/benefits    

The "Electronic traction support" (ETS) is an automatic system for improving starting-off and acceleration capabilities on road surfaces with different adhesion. It replaces the "automatic locking differential" (ASD).
The system works via a brake intervention at the driven wheels. An engine intervention is not carried out.

The ABS and ETS basic components are combined in the ETS hydraulic unit.

The ABS and ETS switching circuits are likewise combined in the ETS electronics.

Brake moment control circuit

ABS prevents the wheels locking during braking and thus maintains steerability and vehicle stability during vehicle deceleration.
ETS prevents the drive wheels spinning on one side when starting off and accelerating and the drive wheels spinning briefly on both sides when cornering within specified speed ranges.
  Advantages

Improves starting-off and acceleration capabilities on road surfaces with different adhesion due to increased traction.

Improves the cornering stability when the drive wheels on both side spin briefly.

A warning lamp signals if a wheel speed does not match the vehicle speed. It thus warns the driver that he has approached the physical driving limits of his vehicle.

GF42.35-P-0001-04A

GF42.35-P-0001-04A Electronic traction system (ETS), function survey    

The speeds of all wheels are recorded and processed in the ETS control module (N47/2).
If the ETS control module (N47/2) recognizes from the speed signals that one or when cornering both drive wheels are tending towards skidding , the ETS control mode starts.

Brake moment control circuit
A distinction is made between two control ranges in ETS control mode:

A Control mode with brake intervention on one side
The skidding drive wheel is braked via the appropriate wheel brake until the calculated drive slip is reached. In this way the other wheel can transmit a drive moment which is higher to the extent of the brake moment (differential lock effect). If, due to this locking differential effect, so much driving moment is transmitted to the wheel with the higher coefficient of friction that this wheel also spins, the brake moment at the spinning wheel is reduced.
To brake the spinning wheel the brake fluid pressure is routed to the brake caliper via a pressure system in the hydraulic unit (pressure increase).
  The brake moment is controlled by pressure increase, pressure holding and pressure reduction via solenoid valves in the ASR/ETS hydraulic unit (A7/3).
This ETS control mode is permitted when the switching on conditions are met only in the speed range of 0-40 km/h.
If the switching on conditions are maintained above the 40 km/h threshold during an acceleration process, the ETS control mode is continued up to max. 80 km/h.

B Control mode with a brake intervention on both sides (cornering)

If both drive wheels spin within a specified speed range when cornering, both wheels are braked to prevent the vehicle breaking away. Brake intervention on both sides is also controlled by pressure increase, pressure holding and pressure reduction.
The speed range in which brake intervention is possible on both sides is between 15 and 80 km/h. Brake intervention on both sides is maintained for a maximum of 2 seconds, even if the conditions for it last longer.

GF42.35-P-4500-01A

GF42.35-P-4500-01A Function of ETS control module    


To adapt to the various engine variants, manual or automatic transmission and different versions of the rear axle brake calipers, control modules must be coded with the Hand-Held Tester after installation in the vehicle variant concerned.

The ETS/SPS control module is divided up functionally as follows:
Signal conditioning
Logic section
Safety circuit
Additional functions

Signal conditioning
The following input signals are conditioned for the logic section:
- 4 speed sensors
- Stop lamp switch, 4-pin
- Terminal 61


Logic section
The conditioned input signals are processed in the logic section and converted into output signals.

The logic section is divided up functionally as follows:
- ETS control mode
- Starting-off control logic (manual transmission)
- Temperature monitoring
  ETS control mode
The control mode for brake intervention on one side is recognized from the vehicle speed and ETS slip recognition between the left and right drive wheel.
Switching on condition: Speed difference between the left and right rear wheel > 4 km/h
Switching off condition: Speed difference between the left and right rear wheel = 2 km/h below the switching-on threshold.
Speed range: 0-40 km/h
If the switching on condition is maintained above 40 km/h during an acceleration process, the control mode is continued up to max. 80 km/h.

The control mode for brake intervention on both sides is recognized from the vehicle speed/cornering and ETS slip recognition.

Switching on condition: Both rear wheels at least 2.8 km/h
faster than the vehicle speed
+
Cornering recognition:
Speed difference between the left and right front wheel > 1 km/h
+
speed range = 15-80 km/h

On period: max. 2 seconds

Starting-off control logic (manual transmission)
A starting-off logic circuit is integrated into the ETS/SPS control module to prevent the engine "stalling" due to brake intervention when starting off.
Depending on the vehicle speed,a mean minimum rear axle speed (= theoretical minimum engine speed) is specified which depends on the current ETS brake control pressure.
If the mean rear axle speed is less than the specified mean minimum rear axle speed, pressure is reduced in the brake caliper.
This control characteristic is varied on vehicles with manual transmission depending on the brake control pressure, mean rear axle speed and vehicle speed between 4 and 28 km/h.

Temperature monitoring
In an exceptional case, there is the risk of the rear wheel brakes overheating due to the dual load of the brake and the ETS control. For this reason the rear wheel brake lining temperature is calculated continuously in the control module and when a calculated lining temperature is reached at the respective brake, no further ETS control is permitted until the temperature has reduced again.
If ETS control is prevented by temperature monitoring, the ETS malfunction indicator lamp comes on and remains on as if the ETS control was effective, but for at least 5 seconds. The exceeded temperature is also retained in the fault memory.
 
Temperature calculation
 The brake lining temperature is calculated separately on the left and right. It is determined without a temperature sensor. The following inputs are evaluated to calculate brake lining temperature.
- Vehicle speed
- Brake operation
- Calculated brake pressure from the ETS control logic

After-running mode after "ignition OFF"
The voltage supply to the ETS/SPS control module is ensured by this operating mode even after "ignition OFF". As a result the brake lining temperatures continue to be calculated and cannot be reset by "ignition OFF/ignition ON". After ignition is switched off, the temperature continues to be calculated until a calculated temperature of 30°C is reached, but for a maximum of 30 minutes. The voltage supply to the ETS/SPS control module is then switched off.







Safety circuit
The task of the safety circuit is to recognize defective components in the control module and faults in the electrical wiring system.. After "ignition ON" and when a speed of 7 km/h is exceeded for the first time, system tests are carried out, which recognize faults at the solenoid valves, the high-pressure/return pump and the speed sensors. Constant monitoring is also carried out even during ABS or ETS control. If a fault is recognized, the system is switched off and this is displayed to the driver by ETS or ABS malfunction indicator lamp (A1e35 or A1e17) coming on. A fault code is also stored in the control module.
The safety circuit also constantly monitors battery voltage. If a voltage of 10.5 V is not achieved the system is also switched off until the voltage is again in the specified range.











  Additional functions

Partial function of speed-sensitive power steering
(models 140, 210)
The control module calculates the specified current for actuating the SPS P-valve (Y10) from the vehicle speed which is available internally and the status signal.

Wheel speed and speed status signal outputs
Wheel speed output: The ETS/SPS control module supplies the current wheel speed of each wheel for systems which need a wheel speed signal.

Speed status signal output: The ETS/SPS control module supplies the speed status signal for systems which need information on the current drive condition (vehicle stationary, vehicle driving, speed sensor defective).

Indicator lamp actuation
The signals from the brake pad wear contacts and the parking brake are recorded as of control module version LK55/1. They are transmitted to the instrument cluster via a serial data bus together with the signals for the ABS and ETS malfunction indicator and warning lamps and on vehicles with CAN connection on the instrument cluster via a CAN data bus.