AUDI A4 2000 B5 / 1.G Brakes Basic Setting 04 Service Manual

On Board Diagnostic (OBD) will be terminated by the ABS control module -J104- if road speed exceeds 19 km/h.
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Output Diagnostic Test Mode (DTM)
(function 03)

Output Diagnostic Test Mode (DTM) is used to
check the function of actuators. Actuators are
also called actors. These are components that
the control module activates when it reacts to the
signals sent by sensors, e.g. solenoid valves,
relays and pump motors.

Note:

Output Diagnostic Test Mode (DTM) only
functions on vehicles containing control
modules with no. 8D0 407 389 A/D/E.
For control modules with no. 4B0 907 389,
output Diagnostic Test Mode (DTM) is not
possible.

Output Diagnostic Test Mode (DTM) can and
must only be selected once after the ignition
is switched on.
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"Function of actuators" includes all functions and
properties of an actuator under operating
conditions. This means, for example:

An electrically operated hydraulic valves that
opens and closes when activated by the control
module.

The relay of an electrical motor when activated
by the control module. The motor switches on
and carry outs the task.
Before initiating the output Diagnostic Test Mode
(DTM), make sure there are no electrical
malfunctions in the system you wish to test. This
will enable you to recognize any mechanical
problems. Perform a guided troubleshooting
before starting output Diagnostic Test Mode
(DTM) page 01
-19
.
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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.
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Notes:

The vehicle must be raised until all wheels are
free to turn. Ask a colleague to help. The
colleague will have to check the wheels to
determine whether they turn freely.
You can stop the test sequence at any time by
pressing the -C- button.
To avoid overloading the components being
checked, they are actuated during the test
sequence for a period of 60 (or 90) seconds.
The actuator test will be terminated if the "
button" is not pressed within this period.

The ABS warning light and the red "brake
system malfunction" symbol blink during the
test.
Pressing the brake pedal repeatedly this
relieves the vacuum in the brake booster. For
this reason, the brake pedal must be pressed
harder in order to achieve the same braking
effect. Your work will be easier if you run the
engine briefly. This will build up vacuum in the
brake booster again.
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During the test, the individual test steps are
shown in the second line of the VAG1551 scan
tool display. The following abbreviations are
used.
IV = Inlet valve
OV = Outlet valve
LF = Left Front
RF = Right Front
LR = Left Rear
RR = Right Rear
B+ = Battery Positive Voltage (B+) at valve
0V = 0 volts; No voltage at valve
Locked/free = Wheel condition; must be checked
by second technician
Hydr-P = Hydraulic pump
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- Connect VAS5051 tester or VAG1551 scan tool
and select the address word 03 "Brake
Electronics".

- Check the control module version page 01
-
128
and press the button.
Rapid data transfer
HELP
Select function XX

Indicated on display:
- Press buttons -0- and -3- to select "Output Diagnostic Test Mode
(DTM)" function 03.
Rapid data transfer
Q
03 - Output Dia
gnostic Test Mode
(DTM
)

Indicated on display:
- Press -Q- button to confirm input.
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Output Diagnostic Test Mode (DTM)
-
ABS hydraulic pump -
V64-

Indicated on display:
ABS hydraulic pump -V64- must start running. This is audible.

When you put your foot on the brake pedal you can feel it vibrating. The
brake pedal vibrates because the hydraulic pump generates pressure
pulses in the brake lines. The pressure pulses generate oscillations.
These are directed to the brake pedal and make it vibrate.
The pressure pulses in the brake lines are not sufficient to lock the
wheels.
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The hydraulic circuit diagram shows a systematic representation of
an ABS/EDL system. This will give a better understanding of the
various test steps in the output Diagnostic Test Mode (DTM).
shaded components are in action.Thin solid lines represent hydraulic lines or hoses that are not under
pressure. Thick broken lines represent hydraulic lines or hoses working as
suction lines. Thick solid lines represent hydraulic lines or hoses that are under
pressure.
-
Press button.
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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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