Anti-Lock Braking System (Abs) Repair Information

General Information

The ABS brake system is divided diagonally. The brake booster operates pneumatically via the vacuum brake booster.

Vehicles with ABS Mark 60 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 Booster.

The conventional brake system remains operative even without ABS.

A change in braking behavior must be anticipated. When the ABS indicator Lamp -K47- is turned on, the rear wheels may lock prematurely when braking.

Component Location:

Fig 1: Configuration

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

1. ABS Hydraulic Unit -N55- with ABS Control Module -J104-
2. 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 pump -3- must not be separated from the ABS Hydraulic Unit -N55-.

Fig 2: ABS Control Module, Hydraulic Unit And Hydraulic Pump Assembly

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Separation is not possible on vehicles with hydraulic brake booster or hill start assist.

Anti-Lock Braking System (ABS) Repair Information

• First determine the cause of the damage and the coding from the ABS Control Module -J104- using the Vehicle Diagnostic Tester before performing any service work on the ABS.

• Disconnect the battery ground cable when the ignition is switched off.
• Before welding with an electric welding tool, observe the appropriate service information .
• The relevant safety precautions and notes must be observed when handling brake fluid. Refer to BRAKE FLUID GENERAL INFORMATION .
• 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 once (pulsing must be felt on the 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 opened components if repairs are not performed immediately (use Sealing Plugs:1H0 698 311 A  ).
• 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.