General Notes on Anti-Lock Braking System
Anti-lock brake system (ABS) and anti-lock brake system with electronic differential lock (ABS/EDL) ITT Mark 20 IE
General
ABS layout (left-hand drive vehicle)
The ABS or ABS/EDL brake system is divided diagonally. Brake pedal pressure is boosted pneumatically by a vacuum brake booster.
Vehicles with ITT Mark 20 IE ABS do not have a mechanical brake pressure regulator. The control module controls the rear axle brake pressure regulation.
Malfunctions of the ABS or ABS/EDL systems do not influence conventional braking or the vacuum brake booster. The conventional braking system remains functional if the ABS is not operating.
The hydraulic part -a- and control module part -b- form one unit. They can only be separated when removed from the vehicle.
New control modules (replacement parts) are not coded and must be coded after installation.
Before working on the ABS or ABS/EDL, determine the cause of the malfunction using the On Board Diagnostic (OBD) program.
Differences between ABS ITT Mark 20 IE and ABS/EDL ITT Mark 20 IE
I - ABS - ITT Mark 20 IE
Dimension a = 100 mm (3.9 inch)
II - ABS/EDL - ITT Mark 20 IE
Dimension a = 130 mm (5.1 inch)
Safety precautions
WARNING! Brake fluid is poisonous.
CAUTION!
^ Before working on ABS or ABS/EDL system, obtain the radio code before disconnecting battery ground strap.
^ Brake fluid must not contact painted parts.
^ Brake fluid absorbs moisture from the air and must therefore be replaced every two years. Use only new, unused and approved brake fluid that complies with MVSS 116 DOT 4.
^ Do not use silicone-based brake fluid (DOT 5). Even the smallest traces can cause severe corrosion in the brake system.
^ Before doing any electric welding on the car, disconnect the ABS control module.
^ After work that requires opening the brake hydraulic system, bleed the system after completion of the repairs go to Brake Bleeding.
^ During the final road test make at least one controlled brake test where the brake pedal is felt to pulsate (ABS operation).
CAUTION!
^ Absolute cleanliness is required when working on the ABS or ABS/EDL system. Do not use any products that contain mineral oil such as oil, greases, etc.
^ Thoroughly clean all connections and the area immediately around them before loosening. Do not use aggressive cleaning agents such as brake cleaner, gasoline or thinners.
^ Place removed parts on a clean surface and cover them. Only use clean plastic covering or paper. Do not use rags that may contain lint.
^ Carefully seat or cover opened components if repairs cannot be completed right away.
^ After separating the control module from the hydraulic unit, use the transportation protection for the valve dome.
^ Only install replacement parts from original packaging. Only remove the parts from the package immediately before installation.
CAUTION!
^ Do not work with compressed air nearby whenever the hydraulic system is open. Do not move the vehicle with the hydraulic system open.
^ Be very careful not to let any brake fluid enter any wiring harness connectors.
^ Do not re-use fasteners that are worn or deformed from normal use.
^ Some fasteners are designed to be used only once and are unreliable and may fail if used a second time. This includes but is not limited to nuts, bolts, washers, clamps, circlips and cotter pins. Always follow the recommendations in this manual. Replace these fasteners with new parts where indicated and any other time it is deemed necessary by inspection.