Output Diagnostic Test Mode (Function 03)

Output Diagnostic Test Mode (function 03)

Note: All functions which could previously be performed with V.A.G 1551 can also be performed with the tester VAS 5051.

Output Diagnostic Test Mode (DTM) allows you to check the function of the hydraulic system and the pump motor for incorrect connections or leaks (brake line connections to brake calipers and function of hydraulic valves).

Note:
^ The vehicle must be raised until all wheels are free to turn. A second technician is required to rotate wheels.
^ The -C- button can be used to exit the test sequence at any time.
^ After depressing the brake pedal several times the vacuum in the brake booster will be exhausted. For this reason, more pressure must be applied to the brake pedal in order to attain the same braking effect.
^ When the vacuum in the brake booster is exhausted the wheels may not lock. Start the engine briefly to build up vacuum in the brake booster.

Example of V.A.G1 551 display during output DTM (left-front wheel, FL shown in example)-.

Indicated on display

IFL: Inlet valve Front Left

VBAT: Battery voltage at valve

OFL: Outlet valve Front Left

0V: 0 Volts (no voltage at valve)

Locked/free: Wheel condition; must be checked by second technician

Indicated on display

Hydr-P- Hydraulic pump
- Connect V.A.G 1551 scan tool.
- Switch ignition on.
- Press button -1 - for "Rapid data transfer" operating mode.
- Press buttons -0- and -3- to insert "Brake Electronics" address word 03.

Indicated on display
- Press -Q- button to confirm input.

Note: During the next procedure steps ABS warning lamp -K47- flashes.

- Read control module version in V.A.G 1551 display.
- Press --> button.

Indicated on display
- Press buttons -0- and -3- to select "Output Diagnostic Test Mode" function 03.

Indicated on display
- Press -Q- button to confirm input.

ABS hydraulic pump display group number- must run.

Indicated on display
- Press --> button.

Indicated on display
- Operate brake pedal.
- Press --> button.

Indicated on display
- Indicate to second technician which wheel requires turning by hand.

If the wheel does not lock, a malfunction may exist in the mechanical and/or hydraulic section of the brake system.
- Press --> button.

Indicated on display
- Press --> button.

ABS hydraulic pump display group number: must run.

Brake pedal must not give.

If the brake pedal gives, there is a malfunction in the hydraulic unit. In this case the hydraulic unit must be replaced.

Indicated on display
- Indicate to second technician which wheel requires turning by hand.

If the wheel locks it is possible that the brake lines to the wheel calipers have been interchanged.
- Press --> button.

ABS hydraulic pump display group number- V64- no longer runs.

Indicated on display
- Press --> button.

Brake pedal must give noticeably.

If the brake pedal does not give, there is a malfunction in the hydraulic unit. In this case the hydraulic unit must be replaced.

Indicated on display
- Remove foot from brake pedal.
- Press --> button.

Indicated on display
- Operate brake pedal.
- Press --> button.

Indicated on display
- Press --> button.

ABS hydraulic pump display group number- must run.

Brake pedal must not give.

If the brake pedal gives, there is a malfunction in the hydraulic unit. In this case the hydraulic unit must be replaced.

Indicated on display
- Remove foot from brake pedal.
- Press --> button.

Indicated on display
- Operate brake pedal.
- Press --> button.

Indicated on display
- Remove foot from brake pedal.
- Press --> button.

Indicated on display
- Operate brake pedal.
- Press --> button.

Indicated on display
- Remove foot from brake pedal.
- Press --> button.

Indicated on display (vehicles with EDL)

A second technician is required to rotate the respective wheel by hand.

If the wheels do not lock, there is a malfunction in the hydraulic part of ABS system. In this case the hydraulic unit must be replaced.
- Press --> button.

ABS warning lamp -K47- goes out.

Indicated on display

Output Diagnostic Test Mode (DTM) is completed.
- Press --> button.

Indicated on display

Note:
^ If ABS warning lamp does not go out there is a malfunction in the system.
^ Adhere exactly to the test sequence- first check DTC memory, then erase.
^ End Output (scan tool function 06).

Checking data bus wiring

Display group number 125
- Press keys 1, 2 and 5
- Confirm entry with key Q.

There are always 4 display zones -arrows- in the measured value block. Decoding the individual values in display zones 1 to 4 can be read from the following tables.

Indicated on display- (vehicle stationary)

Press C key for the next display group number entry.

If the --> key is pressed, keys 0 and 8 for work sequence "Read measured value block" must be pressed again afterwards to regain entry.

1) Vehicles with automatic transmission only.

Note:
^ Incorrect transmission control module or incorrect transmission control module coding.
^ Transmission control module faulty.
2) All wheel drive vehicles with Haldex coupling only.
3) Data bus connection is interrupted or data bus wires are interchanged.