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ESPElectronic Stability Program

327 HO 05 ESP (WJB,GC) 02-26-04

Starting MY1996

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Objectives

At the end of this presentation, you should be able to:1. Explain the function of and purpose for ESP2. Describe the customer interface with ESP3. List the hydraulic and electronic components used for ESP4. Describe the ESP build up, holding and reduction control

modes

These technical training materials are current as of the date noted on the materials, and may be revised or updated without notice. Always check for revised or updated information. To help avoid personal injury to you or others, and to avoid damage to the vehicle on which you are working, you must always ref er to the latest Mercedes -Benz Technical Publication and follow all pertinent instructions when testing, diagnosing or making repair.Illustrations and descriptions in this training reference are based on preliminary information and may not correspond to the final US version vehicles. Refer to the official introduction manual and WIS when available. Copyright Mercedes-Benz USA, LLC, 2004WIS document numbers shown apply to WIS Version USA/CDN at date of writing.Reproduction by any means or by any information storage and retrieval system or translation in whole or part is not permitted without written authorization from Mercedes -Benz USA, LLC or it's successors. Published by Mercedes -Benz USA, LLC Printed in U. S.A.

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Contents

Purpose of ESP 4Driving with ESP 7ESP Electronic components 9Six ESP control modes 19Diagnosing Included ESP Functions 23Other Functions Related to ESP 24ESP block diagram 25

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Purpose of ESP

1. Prevent oversteer and understeer

2. Increase safety by providing stability

It does this by applying the appropriate brake(s)

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Advantages• Improved starting and acceleration capability

• Improved stability when:

• braking

• accelerating

• coasting

• cornering

• Shortens stopping distances in corners or on slippery surfaces

• Informs driver of slippery conditions

• ABS, ASR, EBR and ESP functions are combined in one control unit

• ABS, ASR, EBR and ESP basic components are combined in one hydraulic

unit

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Improved Braking Stability

Additional ESP system sensors provide for further enhanced braking stability.

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Driving with ESP

• Warning lamp flashes when ESP operates.

• The throttle control portion of ESP can be switched off with ESP OFF rocker switch.This will illuminate the warning lamp continuously.(may provide better traction in deep snow or when snow chains are mounted)

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Understeer and OversteerESP monitors the vehicle’s traction and handling, using sensors to

detect wheel speed, understeer and oversteer

Understeer Oversteer

Vehicle does not turn as sharply as desired. The vehicle seems to “plow” straight ahead. ESP will brake the inside rear wheel.

Vehicle turns in more sharply than desired. The rear of the vehicle swings outward. ESP will brake the outside front wheel.

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ESP Electronic Components

A1e17 ABS malfunction indicator lamp A1e41 ESP and ABS warning lamp A1p13 Multifunction displayA7/3n1 SBC control module B24/15 Lateral acceleration and yaw rate

sensor

N47-5 ESP, BAS and SPS control moduleN49 Steering angle sensor N72/1s1 ESP OFF switch X11/4 Diagnostic data link connector

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Steering Angle Sensor (N49)

•N80 - Steering column module

• A45 - SRS & horn clock spring

Signals the desired steering angle to ESP.ESP also recognizes cornering by monitoring input from the 2 front wheel speed sensors.

W220 shown

Front wheels must be straight when removing

and installing A45

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Early Version Steering Angle Sensor (N49)

a b

b - 8 apertures & barriers arranged in a specific pattern

a – 9 evenly spaced light emitting diodes (LEDs)

Must be re-initialized after the battery is disconnected, because N49 has a T.30 power connection.

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Late Version Steering Angle Sensor (N49)

W220 Shown

Screw

N80 = Steering column module

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Lateral Acceleration Sensor (B24/2)

Hall sensor

Magnetic mass

Produces a signal corresponding to the cornering forces.

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Yaw Rate Sensor (N64)

• Hollow cylinder vibrates by means of piezo elements

• Vibration patterns change due to rotary motion of vehicle

• Changes are used as a measure of Yaw rate of the vehicle

Measuring element:

Yaw: to turn around the vertical axis

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Combined Lateral Acceleration & Yaw Rate Sensor (B24/15)

Location shown on 211 chassis

When this component is replaced, adaptation must be performed. (refer to WIS: AD42.45-P-3000-2A)

Senses rotational speed of the vehicle about the vertical axis andthe lateral acceleration.

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Stop Lamp Switch (S9/1)

Two position switch: N.O. and N.C.

It is self-adjusting(NOTE: be sure to pull it all the way out before installing.)

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Stop Lamp Switch Service Note

• ESP fault codes C1200, C1201, C1202 may be set if the stop lamp

switch is misadjusted (implausible signal as compared to BAS

diaphragm travel sensor input)

• Check switch voltage supply

• Ensure correct switch part number is installed

• Adjust as per DTB 33/00 (5-26-00)

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CAN Communication

CAN communication with:• ME-SFI

(for torque reduction)• ETC - Electronic Transmission Control

(utilized for calculation of the ESP regulation)

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Six ESP Control Modes

1. Normal mode2. ABS mode (pressure holding and reduction)3. ASR mode (pressure build up, holding, and reduction)4. EBR mode (slight throttle opening)5. ESP “OFF” mode (switches off throttle control)6. ESP mode (pressure build up, holding, and reduction)

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y19

y22

y18

ESP Pressure Build Up

• BAS applies~5bar pressure

(Note: brake light suppression relay activated)

• y18,y19 close

• m1 activated• y22 opened• y6 closed

Example:Right front wheel requires braking

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ESP Pressure Holding

Example:Right front wheel

• y22 closed, preventing pressure build up

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ESP Pressure Reduction

Example:Right front wheel

• y18 is opened• Pressure returned to the master cylinder

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Diagnosing Included ESP Functions:

• ABS – Anti-lock Brake System• ASR – Acceleration Slip Regulation• EBR – Engine Braking Regulation• EBD – Electronic Brake Force Distribution • ETS – Electronic Traction System• ESP – Electronic Stability Program• BAS – Brake Assist System• 4ETS – 4MATIC

Pre-ESP systems

Post-ESP systems

To diagnose a function contained within ESP using DAS, you may have to begin at the ESP menu.

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Other Functions Related to ESP

• PML (SPS) – Speed Sensitive Steering• CAN communication• Electronic Accelerator (EA) intervention• Electronic Transmission Control (ETC)

intervention• Sensotronic Braking Circuit• Distance (DTR)• Airmatic, ABC, SAS suspension

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ESP Block Diagram

Front VSS

Terminal 61

Stop lamp switch

Data Link (X11/4)

CAN-C (VSS)

Rear VSS

Circuit 31Power

N47/

Return pump Relay K40/

Hydraulic control unit A7/

Parking Brake sw. ESP warning lamp

ESP MIL

ABS MIL

Lateral SensorSteering Angle

Pressure Sensor

Yaw Sensor