Anti-Lock Braking System (Abs) Repair Information
The ABS brake system is divided diagonally. The brake booster operates pneumatically via the vacuum brake booster.
Vehicles with ABS Mark 60 or ABS Mark 70 do not have a mechanical brake pressure regulator. A specially coordinated software program inside the ABS Control Module -J104- determines the brake pressure allocation for the rear axle.
ABS Malfunctions Do Not Affect the Brake System and the Brake Booster
The Conventional Brake System Remains Operative Even without ABS
A Change in Braking Behavior Must Be Anticipated
When the ABS Warning Lamp -K47- is Turned on, the Rear Wheels May Lock Prematurely When Braking.
- ABS Hydraulic Unit -N55- with ABS Control Module -J104-
- Brake Booster with Tandem Brake Master Cylinder
The ABS Control Module -J104- -1- and ABS Hydraulic Unit -N55- -2- are a single unit. Separation is only possible when removed. The hydraulic pump -3- must not be separated from the ABS Hydraulic Unit -N55-.
Separation is not possible on vehicles with hydraulic brake booster or hill start assist.
- Before servicing the ABS system determine the cause of damage as well as the coding of the ABS Control Module -J104-. Refer to Vehicle Diagnostic Tester.
- Disconnect the battery ground cable when the ignition is switched off.
- Before welding with an electric welding tool, observe the information found in the appropriate service information.
- When handling brake fluid, observe the relevant safety precautions and notes. Refer to HYDRAULIC SYSTEM .
- After finishing any work that required opening the brake system, bleed the brake system using the Brake Charger/Bleeder Unit: VAS5234 .
- During the final road test, make sure a controlled braking maneuver is performed at least one time (pulsing must be felt in brake pedal).
- It is necessary to maintain a high level of cleanliness when working on the ABS system.
- Do not use any products containing mineral oil, such as oils, greases, etc.
- Thoroughly clean all connection points and their surrounding areas before loosening. However, do not use aggressive cleaning agents such as brake cleaner, gasoline, thinners or similar compounds.
- Place the removed parts on a clean surface and cover them.
- Use the valve body transportation protection after disconnecting the ABS Control Module -J104- and the ABS Hydraulic Unit -N55-.
- Carefully cover or seal any open components if the repairs cannot be performed immediately (use Plugs).
- Only use lint-free cloths.
- Remove the replacement parts from their packaging just prior to installing them.
- Only use parts in their original packaging.
- Do not work with compressed air and do not move the vehicle when the system is open.
- The ABS Control Module -J104- may be briefly exposed to a maximum temperature of 95 °C (203 °F) when painting.
- The ABS Control Module -J104- may be exposed to a maximum temperature of 85 °C (185 °F) for a longer period of time (approximately 2 hours).
- Make sure that brake fluid cannot get into the connectors.
For the ABS-Mark 60 EC in this vehicle, the Transverse Acceleration Sensor -G200-, the Rotation Rate Sensor -G202- and the Longitudinal Acceleration Sensor -G251- (depending on the vehicle equipment level) are installed in the ABS Control Module -J104-.
It is not possible to replace them separately.
-- ABS Control Module -J104-, Removing and installing. Refer to ABS Control Module -J104- /ABS Hydraulic Unit -N55-, REMOVING AND INSTALLING, WITH 4-CYLINDER GASOLINE ENGINE AND ABS MARK 60 EC ABS/EDL/ASR/ESP .
Vehicles without Electro-Mechanical Power Steering
The Steering Angle Sensor -G85- is installed on the steering column. Refer to Steering Angle Sensor -G85- ON STEERING COLUMN .
Steering Angle Sensor -G85-, removing and installing at the steering column. Refer to STEERING ANGLE SENSOR -G85-, REMOVING AND INSTALLING .
Vehicles with Electro-Mechanical Power Steering
The Steering Angle Sensor -G85- is located in the steering gear. Refer to STEERING ANGLE SENSOR -G85-, REMOVING AND INSTALLING .
The Steering Angle Sensor -G85- cannot be replaced separately.
Use the Vehicle Diagnostic Tester for fault diagnostics.
Steering Angle Sensor -G85-, removing and installing. Refer to STEERING ANGLE SENSOR -G85-, REMOVING AND INSTALLING .