MAN EHLA ALA Steering System T57 System Description 2009 – TGM TGS TGX Bus Coach Manual

Description

MAN EHLA ALA Steering Systems – System Description T57

This System Description T57 covers the Electro-Hydraulic Steering System (EHLA®) and the Adhesion-Steered Steering System (ALA) as used across MAN commercial vehicles. It is the 1st edition, published March 2009, document number 81.99593-7202, and applies to Trucknology Generation M, S and X models as well as multiple bus and coach ranges.

Whether you are diagnosing a steering fault, replacing a steering angle sensor, calibrating an axle, or tracing a wiring fault through the T-CAN databus, this manual provides the functional descriptions, component locations, connector pin assignments, fault code lists and wiring diagrams needed to carry out the work correctly.

File Details

• Manual type: System Description
• Brand: MAN Nutzfahrzeuge AG
• Systems covered: EHLA (Electro-Hydraulic Steering System), ALA (Adhesion-Steered Steering System)
• Language: English
• Page count: 130
• File format: PDF
• Document number: 81.99593-7202
• Edition: 1st edition
• Date: 03.2009

Chapters Covered

• Abbreviations
• Introduction
• Device Description
• Wiring Diagrams

Introduction

Covers safety instructions, an overview of models, and explanatory notes to the wiring diagrams. The model overview lists all TGM, TGS, TGX, and bus/coach variants to which this system description applies, including LION’S CITY, CITYLINER, TOURLINER, TRENDLINER, LION’S COACH and LION’S REGIO models. Installation position identifiers for left-hand drive and right-hand drive vehicles are included.

Device Description – System and Functional Description

Explains how the electro-hydraulic steering system works as a closed control circuit. The front axle steering angle is measured and sent to the control unit, which calculates a setpoint for the rear axle as a function of vehicle geometry and speed. The steering movement is implemented via a proportional hydraulic unit and steering cylinders. The position of the steered rear axle is read back and compared with the setpoint. The manual also covers the ALA system, which measures the angle of a self-steering axle and makes it available on the T-CAN databus, and can centre the axle.

Component Description

Detailed descriptions and connector pin assignments for the EHLA control unit (A805), steering angle sensors for front axle (B283) and trailing/leading axle (B284), the control valve (Y333), the trailing axle solenoid valve (Y325) for ALA, the steering oil level switch (B432), and the freewheel valve. Installation positions with photographic references are provided for TGM, TGS, TGX, and buses/coaches with TEPS. Sensor curves, voltage ranges and technical data are documented for all steering angle sensors.

Diagnosis

Covers the diagnostic system structure, K-line and KWP-on-CAN communication, the diagnosis socket X200 (12-pin and HD-OBD 16-pin), gateway functions via the vehicle management computer, on-board diagnosis procedures using the driver’s display, and fault code reading with MAN-cats® II. Includes priority displays, FMI (Failure Mode Identification) definitions, and global vs. specific fault text message structures.

SPN Fault Code Lists – EHLA and ALA

Two comprehensive fault code lists document the SPN (Suspect Parameter Number) codes for EHLA and ALA systems. Each entry includes fault status (FMI), priority, fault display, effect of fault, cause of fault and remedy. Coverage includes steering angle sensor faults, proportional valve output faults, CAN communication errors, EOL parameterisation faults, voltage supply problems, internal control unit errors, and many more. These lists are essential for interpreting MAN-cats diagnostic readouts and on-board display fault messages.

Wiring Diagrams

Provides complete wiring diagrams for EHLA on TGM/TGS/TGX, EHLA on buses and coaches with TEPS, and ALA on buses and coaches with TEPS. Diagrams show the EHLA control unit (A805) connections to the front axle steering angle sensor (B283), trailing/leading axle steering angle sensor (B284), control valve (Y333), trailing axle solenoid valve (Y325), T-CAN databus, and power supply via fuse F726. All connector pin numbers, line numbers, and wire colours are documented.

What This Manual Enables You to Do

This MAN EHLA ALA Steering System T57 System Description manual gives you the technical foundation to understand, diagnose and repair the electro-hydraulic and adhesion-steered steering systems fitted to a wide range of MAN vehicles. Because the steering system is safety-critical, having the correct functional description and fault code interpretation is not optional – it is the difference between a correct repair and a comeback.

With this manual you can:

• Understand the complete EHLA closed-loop control circuit and ALA system architecture
• Identify all steering system components by their MAN designation and installation position
• Read and interpret SPN fault codes for both EHLA and ALA, with cause and remedy for each
• Perform calibration of steering angle sensors after component replacement or geometry changes
• Trace wiring faults using the dedicated EHLA and ALA wiring diagrams for trucks and buses
• Check connector pin assignments for the EHLA control unit, steering angle sensors, control valve and solenoid valves
• Diagnose faults via MAN-cats II, the on-board diagnosis menu, and the instrumentation display
• Understand the safety concept behind the system, including the bypass/freewheel valve function

Why This Manual Matters

Steering system faults on commercial vehicles are not something to guess at. The EHLA and ALA systems interact with the vehicle’s T-CAN databus, EBS, ESP and engine management. A misdiagnosed steering angle sensor, incorrectly calibrated axle, or overlooked CAN communication fault can lead to emergency steering mode, reduced manoeuvrability, or worse. This manual provides the exact fault code descriptions, component specifications and wiring details that let you diagnose with confidence.

The SPN fault code lists alone are worth the investment – they turn a cryptic fault code into a clear cause-and-remedy procedure. Combined with the wiring diagrams and component pin assignments, you have a complete diagnostic and repair resource for MAN EHLA and ALA steering systems.

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This MAN EHLA ALA Steering System T57 System Description is delivered as an instant PDF download. No shipping, no waiting. Once purchased, you can access the manual immediately on any device – desktop, laptop, tablet or smartphone. Print the pages you need for the workshop, or keep the entire manual on your diagnostic laptop for quick reference. The PDF format means you can zoom in on wiring diagrams, search for fault codes, and carry the full document wherever the vehicle is.