brake fluid AUDI A4 1999 B5 / 1.G Brakes Basic Setting 04 Workshop Manual

01-286

Output Diagnostic Test Mode (DTM)
-
Operate brake

Indicated on display:
-
Press button.
Output Diagnostic Test Mode (DTM)
-
Ifl: 0V
Ofl: 0V
fl wheel locked

Indicated on display:

When you press the brake pedal, brake fluid pressure will be built up in all
four calipers. All four wheels lock.
Requirement for this: mechanical/hydraulic components of the brake
system must be fully functional. This means that the master brake cylinder
is able to build up pressure in all wheel cylinders and the hydraulic
connections and lines are all sealed properly.
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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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pair&id=AUDI.B5.SU02.01.15

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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01-292

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.
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01-299

Output Diagnostic Test Mode (DTM)
-
Irr: B+
Orr: B+
rr wheel free

Indicated on display:

The EDL change-over valve (left) and the EDL inlet valve are activated.
ABS return flow pump -V39- runs for one second. It draws brake fluid from
the brake fluid expansion tank via the EDL inlet valve. The hydraulic pump
builds brake fluid pressure in the EDL regulated wheel cylinders. These
wheels will then be locked.
If not, this indicates a mechanical malfunction in one of the valves,
providing there is no electrical malfunction in the system. Replace
hydraulic control unit.
-
Press button.
Pa
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yp
e=re
pair&id=AUDI.B5.SU02.01.15