Output Diagnostic Test Mode (Function 03)

Output Diagnostic Test mode (DTM)
The pump motor and correct function of hydraulic circuits (application of brake lines to wheel cylinders and function of valves) can be checked via Output Diagnostic Test mode (DTM) for interchanging or leaks.

Note:
^ Vehicle must be raised until all wheels are free to turn. (2nd mechanic required to rotate wheels)
^ -C- button can be used to exit test sequence at any time.
^ After Pressing brake pedal several times vacuum in brake booster will be exhausted. Therefore more pressure must be applied to the brake pedal in order to attain same fluid pressure in brake system, as attained with vacuum.
^ When vacuum in brake booster is exhausted wheels may not lock; start engine and build-up vacuum in brake booster.

Example:
Indicated on VAG 1551 display during Output Diagnostic Test mode (DTM)

(e.g. left front wheel, LF)
IFL = Inlet valve Left Front
VBAT = Voltage Battery; Voltage at valve
OFL = Outlet valve Left Front
OV = 0 Volt; No voltage at valve

Locked/free = Wheel condition; have 2nd mechanic check if required
Hydr-P = Hydraulic pump -V64-

- Connect Scan tool VAG 1551.
- Switch on ignition.
- Press button -1- for "Rapid data transfer" operating mode.
- Select brake electronics Control Module address word -03-. VAG 1551 Scan Tool Connecting and Selecting Function

Indicated on display
- Confirm entry with -Q- button.

Note:
^ During next work steps ABS warning light -K47- flashes.

- Read Control Module version in VAG 1551 display
- Press -> button.

Indicated on display
- Press buttons -0- and -3-

Indicated on display
- Confirm entry with -Q- button.

ABS hydraulic pump -V64- must run.

Indicated on display
- Press -> button.

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

Indicated on display
- Indicate to 2nd mechanic which wheel requires tuning.

Note:
^ If wheel does not lock, a malfunction may exist in mechanical/hydraulic part of brake system.

- Press -> button.

Indicated on display
- Press -> button.

ABS hydraulic pump -V64- must run.
Brake pedal must not give.
If brake pedal does not give, a malfunction exists in hydraulic unit -N55-. In this case hydraulic unit must be replaced.

Indicated on display
- Indicate to 2nd mechanic which wheel requires turning by hand.

Note:
^ If wheel locks brake lines to wheel calipers/cylinders may have been interchanged.

- Press -> button.

ABS Hydraulic Pump -V64- not running

Indicated on display
- Press -> button.

Brake pedal must give perceptibly
If brake pedal does not give, a malfunction exists in hydraulic unit -N55-. In this case hydraulic unit must be replaced.

Indicated on display
- Indicate to 2nd mechanic which wheel requires turning by hand.

Note:
^ If wheel does not lock, a malfunction may exist in mechanical/hydraulic part of brake system.

- Press -> button.

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 -V64- must run.
Brake pedal must not give
If brake pedal gives, a malfunction exists in hydraulic unit -N55-. In this case hydraulic unit must be replaced.

Indicated on display
- Indicate to 2nd mechanic which wheel requires turning by hand.

Note:
^ If wheel locks, a malfunction may exist in mechanical/hydraulic part of brake system.

- Press -> button.

ABS hydraulic pump -V64- does run not

Indicated on display
- Press -> button.

Brake pedal must give perceptibly
If brake pedal does not give, a malfunction exists in hydraulic unit -N55-. In this case 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-V64- must run.
Brake pedal must not give
If brake pedal gives, a malfunction exists in hydraulic unit -N55-. In this case hydraulic unit must be replaced.

Indicated on display
- Press -> button.

Brake pedal must give perceptibly
If brake pedal does not give, a malfunction exists in hydraulic unit -N55-. In this case hydraulic unit must be replaced.

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

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

Indicated on display
- Press -> button.

Brake pedal must give perceptibly
If brake pedal does not give, a malfunction exists in hydraulic unit -N55-. In this case hydraulic unit must be replaced.

Indicated on display
- Indicate to 2nd mechanic which wheel requires tuning by hand.

Note:
^ If wheel does not lock, a malfunction may exist in mechanical/hydraulic part of brake system.

- Press -> button.

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

Indicated on display (vehicles with EDL)
- A 2nd mechanic is required to rotate the respective wheel by hand.

If wheels do not lock, a malfunction exists in hydraulic unit -N55-. In this case hydraulic unit must be replaced.
- Press -> button.

The ABS warning light -K47- goes out.

Indicated on display
Output Diagnostic Test mode (DTM) is completed
- Press -> button.

Indicated on display

Note:
^ If ABS warning light does not go out a malfunction exists in system.
^ Adhere exactly to test sequence: First check DTC memory, then erase.

- End output (Function -06-). Erasing DTC Memory, Ending Output