1997 VOLKSWAGEN PASSAT differential

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Anti-lock Brake System (ABS)
and ABS with Electronic
Differential Lock (ABS/EDL),
Teves 20 GI

General information The ABS or ABS/EDL braking system is divided
diagonally. Brake pedal pressure is boosted
pneumatically, by the vacuum brake booster.
Vehicles with Teves 20 GI ABS or ABS/EDL do not
have a mechanical brake pressure regulator.
Specially matched software in the ABS control
module regulates rear axle brake pressure. The ABS hydraulic unit -a- and ABS control module -
b- together make up one component. Separating
them for service is only possible after the assembly
has been removed.
New ABS control units supplied as replacement parts
from the Parts department are not coded, and require
coding after installation:
Repair Manual, Brake System On Board Diagnostic (OBD), Repair Group 01
Malfunctions of the ABS or ABS/EDL system do not
influence the brake system or the vacuum brake
booster. The conventional brake system remains
functional even without ABS.
Before working on the ABS or ABS/EDL system,
determine the cause of the malfunction using the On
Board Diagnostic (OBD) program % Repair Manual,
ABS & ABS/EDL On Board Diagnostic. Page 1 of 3Anti-lock Brake System (ABS) and ABS with Electronic Differential Lock (ABS/EDL), Teves 20 GI12/7/2004http://ebahn.bentleypublishers.com/vw/servlet/Display?action=Goto&type=repair&id=VW.B4.SU01.45.2

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Safety precautions

WARNING!

Brake fluid is poisonous.

CAUTION!
Before working on the ABS or ABS/EDL
system, disconnect the battery Ground
(GND) strap. For anti-theft coded radios, first
make sure that the radio code is available.
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, approved brake fluid
that complies with MVSS 116 DOT 4.
DO NOT use silicone-brake fluid (DOT 5).
Even the smallest traces can cause sever
corrosion in the brake system.
Before doing any welding repairs on the
vehicle using electric welding equipment,
disconnect the ABS control module.
After work that requires opening the brake
hydraulic system, bleed the system Page 47-29 . Page 2 of 3Anti-lock Brake System (ABS) and ABS with Electronic Differential Lock (ABS/EDL), Teves 20 GI12/7/2004http://ebahn.bentleypublishers.com/vw/servlet/Display?action=Goto&type=repair&id=VW.B4.SU01.45.2

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CAUTION!
During the final road test, make sure that at
least one controlled brake test is included
(pulsations must be felt at the brake pedal).
Absolute cleanliness is required when
working on the ABS or ABS/EDL system. DO
NOT use any products that contain mineral
oil, such as oils, greases, etc.
Thoroughly clean all connections and the
immediate vicinity before loosening. DO NOT
use aggressive cleaning agents such as
brake cleaner, gasoline or thinners.
Place removed parts on a clean surface and
cover. DO NOT use fluffy cloths.
Carefully seal or cover opened components
if a repair cannot be completed immediately.
After separating the ABS hydraulic unit and
ABS control module, always use the plastic
foam transportation protection for the valve
dome, and always use the sealing plug kit
Part No. 1 H0 693 311 A.
Only install replacement parts that were
packed in their original packaging. Only
remove them immediately before installation. When the hydraulic system is open DO NOT
work with compressed air in the vicinity and
DO NOT move the vehicle.
Take precautions to make sure that brake
fluid does not enter any wiring harness
connectors. Page 3 of 3Anti-lock Brake System (ABS) and ABS with Electronic Differential Lock (ABS/EDL), Teves 20 GI12/7/2004http://ebahn.bentleypublishers.com/vw/servlet/Display?action=Goto&type=repair&id=VW.B4.SU01.45.2