Checking Hall sensor — AUDI

AJL
The Hall sensor indicates the ignition position for cylinder 1.

If the Hall sensor fails to function, the knock control is switched off and the ignition timing is retarded slightly because the signals can no longer be assigned to the cylinders.

Even without a signal from the Hall sensor, the engine will continue to run and can also be restarted.

When a fault is detected, the engine control unit produces one spark for each cylinder on every crankshaft revolution.
The fact that the control unit is out of phase by one engine revolution does not have any noticeable effect on the injection system. If this happens, the fuel is injected "upstream" (before the closed inlet valve) instead of while the inlet valve is open. This has only a minor influence on the quality of the air/fuel mixture.

Checking activation of Hall sensor

Push back the rubber sleeve on the Hall sensor connector.
Connect the V.A.G 1527 diode test lamp to contacts 1 and 2 on the Hall sensor connector from behind (the connector remains attached to the Hall sensor).

Note:

The connector contacts are numbered on the back of the connector.

Operate the starter for a few seconds.

The diode test lamp must flash briefly on each second engine revolution.

If the diode test lamp does not flash:

Check the power supply for the Hall sensor

Unplug the connector from the Hall sensor.
Switch the ignition on.
Connect the V.A.G 1526 handheld multimeter for voltage measurement contact 1 on the connector and the engine earth.

Specification: 4.5 ... 5.5 V

Checking signal line for Hall sensor

Connect V.A.G 1526 handheld multimeter (voltage scale) to contact 2 on the relevant connector and engine earth.
Switch the ignition on.

Specification: approx. battery voltage

Checking the earth wire for the Hall sensor

Connect the V.A.G 1526 handheld multimeter for resistance measurement between contact 3 on the connector and the engine earth.

Specification: Continuity.

Wiring resistance: max. 1.5 Ohm

If the specified values are all achieved and the diode test lamp does not flash (measured between contacts 1 and 2 with starter connector attached),

Renew relevant Hall sensor.

If the specified results are not achieved, check wiring => Page
28-28
.

Check the wiring between the Hall sensor and engine control unit

Connect test box V.A.G 1598/22 to wiring harness for engine control unit =>Page
24-7
Check the wiring from the Hall sensor ...
...to engine control unit for checking for open circuit and short to positive or earth.

3-pin connector on the wiring harness contact · Test box V.A.G 1598/22, socket
1 (positive) · 62
2 (signal) · 76
3 (earth) · 67

Wiring resistance: max. 1.5 Ohm

Rectify short circuit or open circuit if necessary.