1998 AUDI A4 ESP

01-280
Are you sure there are no electrical malfunctions
in the system? If you have made sure that there
are no electrical malfunctions in the system, you
will be able to identify any mechanical
malfunctions in the individual actuators if the
results of the output DTM are not as specified
here. Replace the relevant part.
With the Bosch 5.3 ABS/ESP the output
Diagnostic Test Mode (DTM) enables you to
check the electrically actuated hydraulic valves
and the pump motor in the hydraulic module. You
can also check that the brake lines going to the
four wheels are connected correctly.
Pa
ge 44 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

01-287


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.
Pa
ge 51 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

01-288

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
ge 52 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

01-290
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
)
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