display AUDI A4 1998 B5 / 1.G Brakes Basic Setting 04 Owner's Guide

01-277
Test table: display group 125 Read measuring value block
125
Indicated on display
Steering angle

0 or 1 Engine
0 or 1
Transmission
0 or 1 not
used



Transmission Control Module (TCM): (only for vehicles with automatic transmission)

0: No information received from the Transmission Control Module (TCM) via the CAN-bus.
1: Information is being received from the Transmission Control Module (TCM) via the CAN-
bus.

Engine Control Module (ECM):

0: No information received from the Engine Control Module (ECM) via the CAN-bus.
1: Information is being received from the Engine Control Module (ECM) via the CAN-bus.
Steering angle sensor:

0: No information received from the steering angle sensor via the CAN-bus.
1)
1: Information is being received from the steering angle sensor via the CAN-bus.
1) If the steering angle sensor is OK, it sends information, even if the zeroing procedure was not performed.
Note:
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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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01-283

- 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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01-284

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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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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01-288

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.
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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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01-291

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.
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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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01-293

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.
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