AUDI A4 1998 B5 / 1.G Brakes Basic Setting 04 Repair Manual

01-287


If the wheels do not lock, visually inspect brake fluid reservoir, master
brake cylinder, hydraulic unit, and calipers.
Concentrate on the left-front wheel first. The function of the control
elements for this wheel is tested first.
Note:
This test step in the output diagnostic test mode corresponds to the
"pressure build-up" phase during ABS-controlled braking.
-
Press button.
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01-288

Output Diagnostic Test Mode (DTM)
-
Ifl: B+
Ofl: 0V
fl wheel locked

Indicated on display:
- Keep pressing brake pedal.

Inlet valve is activated. It interrupts the brake line. However, fluid pressure
is still maintained in the wheel cylinder. The left-front wheel remains
locked.
Note:
This test step in the output diagnostic test mode corresponds to the
"maintain pressure" phase during ABS-controlled braking.
-
Press button.
Pa
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01-289

Output Diagnostic Test Mode (DTM)
-
Ifl: B+
Ofl: B+
fl wheel free

Indicated on display:

Keep pressing brake pedal. The inlet valve and the outlet valve for the
left-front wheel are activated. The hydraulic pump starts running and
reduces the fluid pressure in the caliper via the open outlet valve.
The brake pedal must not give, and should press harder against your
foot.
You should now be able to turn the left-front wheel.
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01-290
If you cannot turn the wheel, check whether the
brake line for the left-front wheels is connected
correctly.

If yes, this indicates a mechanical malfunction in one of the valves,
providing there is no electrical malfunction in the system. Replace
hydraulic control unit.
If the pedal gives under your foot, this means that the inlet valve or the
check valve activated in parallel to the inlet valve is leaking. Replace
hydraulic unit.
Note:
This test step in the output diagnostic test mode corresponds to the
"pressure reduction" phase during ABS-controlled braking.
-
Press button.
Pa
ge 54 of 64 Basic settin
g (scan tool function 04
)
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p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.SU02.01.15

01-291

Output Diagnostic Test Mode (DTM)
-
Ifl: B+
Ofl: 0V
fl wheel free

Indicated on display:
ABS hydraulic pump -V64- will stop running.
- Keep pressing brake pedal. Only the inlet valve is still activated and
interrupts the brake line. If the inlet valve is not leaking, you should be
able to turn the left-front wheel.

If you cannot turn the wheel, this means that the inlet valve or the check
valve activated in parallel to the inlet valve is leaking. Replace hydraulic
control unit.
-
Press button.
Pa
ge 55 of 64 Basic settin
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yp
e=re
pair&id=AUDI.B5.SU02.01.15

01-292

Output Diagnostic Test Mode (DTM)
-
Ifl: 0V
Ofl: 0V
fl wheel locked

Indicated on display:

- Keep pressing brake pedal. Inlet valve is no longer being activated. It is
no longer interrupting the brake line. The brake pedal will give
perceptibly under your foot. Fluid pressure is built again in the left-front
caliper. The wheel will be locked.
-
Press button.
Pa
ge 56 of 64 Basic settin
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pair&id=AUDI.B5.SU02.01.15

01-293

Output Diagnostic Test Mode (DTM)
-
Release brake

Indicated on display:
Continue output Diagnostic Test Mode (DTM) in order to check the
front right, rear left, and rear right wheels in sequence. The test
steps indicate the procedure for the front left wheel. They will
therefore not be repeated in detail. -
Press button.
Pa
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pair&id=AUDI.B5.SU02.01.15

01-294

Output Diagnostic Test Mode (DTM)
-
Operate brake

Indicated on display:
-
Press button.
Output Diagnostic Test Mode (DTM)
-
Ifr: 0V
Ofr: 0V
fr wheel locked

Indicated on display:
-
Press button.
Output Diagnostic Test Mode (DTM)
-
Ifr: B+
Ofr: 0V
fr wheel locked

Indicated on display:
ABS hydraulic pump -V64- must start running.
The brake pedal must not give. -
Press button.
Output Diagnostic Test Mode (DTM)
-
Ifr: B+
Ofr: B+
fr wheel free

Indicated on display:
ABS hydraulic pump -V64- will stop running. -
Press button.
Pa
ge 58 of 64 Basic settin
g (scan tool function 04
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11/20/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.SU02.01.15

01-295

Output Diagnostic Test Mode (DTM)
-
Ifr: B+
Ofr: 0V
fr wheel free

Indicated on display:
Brake pedal must give noticeably. -
Press button.
Output Diagnostic Test Mode (DTM)
-
Ifr: 0V
Ofr: 0V
fr wheel locked

Indicated on display:
-
Press button.
Output Diagnostic Test Mode (DTM)
-
Release brake

Indicated on display:
-
Press button.
Output Diagnostic Test Mode (DTM)
-
Operate brake

Indicated on display:
-
Press button.
Output Diagnostic Test Mode (DTM)
-
Irl 0V
Orl: 0V
rl wheel locked

Indicated on display:
-
Press button.
Pa
ge 59 of 64 Basic settin
g (scan tool function 04
)
11/20/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.SU02.01.15

01-296

Output Diagnostic Test Mode (DTM)
-
Irl B+
Orl: 0V
rl wheel locked

Indicated on display:
ABS hydraulic pump -V64- must start running.
The brake pedal must not give. -
Press button.
Output Diagnostic Test Mode (DTM)
-
Irl B+
Orl: B+
rl wheel free

Indicated on display:
ABS hydraulic pump -V64- will stop running. -
Press button.
Output Diagnostic Test Mode (DTM)
-
Irl B+
Orl: 0V
rl wheel free

Indicated on display:
Brake pedal must give noticeably. -
Press button.
Output Diagnostic Test Mode (DTM)
-
Irl 0V
Orl: 0V
rl wheel locked

Indicated on display:
-
Press button.
Pa
ge 60 of 64 Basic settin
g (scan tool function 04
)
11/20/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.SU02.01.15