1997 AUDI A4 Brakes ABS EDL ASR Bosch 5.3 Workshop Manual

01-120


ABS/EDL/ASR Bosch 5.3

Warning light, functional overview


If On Board Diagnostic (OBD) has detected a
malfunction in the system, it indicates the
malfunction by lighting up warning lamps when
ignition is switched on. The warning lamps are
located in the instrument cluster.

Instrument cluster without DIS
The illustration shows the ABS/EDL warning light -K47- (right arrow),
the warning light for brake system -K118- (center arrow, red symbol
for "brake system malfunction") and the traction control indicator light -
K86- (left arrow).

Instrument cluster with DIS
For DIS, there is no warning light for brake system -K118-. The red
"brake system malfunction" symbol appears in the display. If the ABS/EDL warning light -K47 and the red symbol for "Brake
system malfunction" are not lit, but the brake system is not functioning
properly, check for malfunctions in the mechanical/hydraulic brake
system components.
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Repair manual, Brake System, Repair Group 46

Repair manual, Brake System, Repair Group 47
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01-121

ABS/EDL
-K47- Brake
system ASR

-
K86-
1) Reasons why the indicator lamps light up

If an irregularity occurs during the self test after ignition is switched on, and the
warning lamps -K47- and -K86- do not light up for 2 seconds, check the warning lamps;
"Electrical test" page 01
-166
, carry out test steps 8 and 10. The possible causes are
as follows:
Electrical Wiring Diagrams, Troubleshooting & Component Locations
Repair Manual, Electrical Equipment, Repair Group 27, Battery

The battery voltage is insufficient. None of the lamps in the instrument cluster light up.
Check the battery.





X 1)
The ABS/EDL warning light does not light up during the self-test. There is a short to
Ground (GND) in the wiring that controls the ABS/EDL warning light between terminal 21
of the ABS control module -J104- and the instrument cluster. This malfunction does not
affect activation of the ABS warning light. For vehicles equipped with ASR, the traction
control indicator lamp lights up during the self-test; "Electrical test" page 01
-166
, carry
out test step 8.

X


The vehicle is equipped with ASR. The ABS/EDL warning light lights up during the self-
test. The traction control indicator light does not light up during the self-test "Electrical
test" page 01
-166
, carry out test step 10.
1) The traction control indicator light is only available in vehicles equipped with ASR.
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01-122

ABS/EDL
-K47- Brake
system ASR

-
K86-
1) Reasons why the indicator lamps light up










X










X1) For all vehicles:
For vehicles with control modules that do not provide EBD emergency mode:
If activation of both the ABS warning light -K47- and traction control indicator light -K86- is
OK and the voltage supply is OK, the warning lamps light up for 2 seconds during the self-
test after ignition is switched on.
Check the voltage supply for the red "brake system malfunction" symbol. Carry out
"Electrical test" step 9, page 01
-166
. If the control is malfunctioning, see the next
example for lighted indicator lights.
For DTCs stored in DTC memory that are no longer detected during the self-test when
ignition is switched on or when a specific vehicle speed is reached and are found to be OK
when checked, the red "brake system malfunction" symbol does not light up. For
example:If there was a dynamic malfunction of the wheel speed sensor during the last
driving period, the warning lamps automatically switch off after vehicle is restarted if wheel
speed sensor is tested as OK once a vehicle speed of 2.75 km/h is reached.
- These vehicles can be identified by checking the note column under "Check control module
version"; page 01
-128
.
Voltage supply for the ABS control module -J104- is between 7 and 10 volts and the
vehicle speed is 12 km/h. If the vehicle speed exceeds 6 km/h, a DTC entry will be
made in DTC memory. At a vehicle speed of > 12 km/h, the red "brake system
malfunction" symbol lights up; "Check DTC memory" page 01
-187

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1) The traction control indicator light is only available in vehicles equipped with ASR.
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01-123

ABS/EDL
-K47- Brake
system ASR

-
K86-
1) Possible reasons why the indicator lamps light up






X






X1) For vehicles with control modules that provide EBD emergency mode:
- These vehicles can be identified by checking the note column under "Check control module
version"; page 01
-128
.
A DTC is stored in the DTC memory the first time the vehicle exceeds 6 km/h, if the
voltage supply to the ABS control module -J104- is between 7 and 10 volts and the
indicator lights go on. If the voltage supply of the ABS control module -J104- exceeds 10
volts while driving, the indicator lights switch off. The DTC remains in the memory. If the
voltage supply value drops below 10 volts again during the same driving cycle, the
indicator lamps light up again. "Check DTC memory" page 01
-187

The indicator lights do not switch off after the self-test. However, the red "brake system
malfunction" symbol did not go on. On Board Diagnostic (OBD) recognized a malfunction
that did not deactivate the Electronic Brake Distribution (EBD) system. "Check DTC
memory" page 01
-187

1) The traction control indicator light is only available in vehicles equipped with ASR.
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01-124

ABS/EDL
-K47- Brake
system ASR

-
K86-
1) Reasons why the indicator lamps light up









X









X









X1) The vehicle can be equipped either with or without ASR. The ABS/EDL lamp remains
constantly lit after ignition is switched on and the the red "brake system malfunction" symbol
also lights up 3 seconds after ignition is switched on.
WARNING!
Driving the vehicle presents the risk of accident! The brake system will only be partially
functional. Because brake pressure at the rear wheels is no longer regulated vie
Electronic Brake Distribution (EBD), the rear wheels tend to brake excessively. This
causes the rear of the vehicle to break loose.
For all vehicles:

The VAG1551 Scan Tool (ST) is connected and the data link to the ABS control module
(w/EDL) -J104- was established. For vehicles with automatic transmission and high-line
instrument cluster, the red "brake system malfunction" symbol does not appear
immediately after the ignition is switched on. Instead, the note "Depress brake pedal
before engaging gear" appears in the display. Press the brake pedal and select a gear.
The red brake warning light appears, if the light control is working properly.
On Board Diagnostic (OBD) recognized a malfunction that led to deactivation of Electronic
Brake Distribution (EBD), ABS, EDL or ASR. "Check DTC memory" page 01
-187

1) The traction control indicator light is only available in vehicles equipped with ASR.
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01-125

ABS/EDL
-K47- Brake
system ASR
-K86-
1) Possible reasons why the indicator lamps light up




X




X




X1) Additional information for vehicles with control modules that do not provide EBD
emergency mode:
- These vehicles can be identified by checking the note column under "Check control
module version"; page 01
-128
.
Voltage supply for the ABS control module -J104- is between 7 and 10 volts and the
vehicle speed is > 12 km/h. A DTC will be entered in DTC memory once vehicle reaches
a speed > 6 km/h. "Check DTC memory" page 01
-187

1) The traction control indicator light is only available in vehicles equipped with ASR.
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