Audi Workshop Service and Repair Manuals

Checking Hall sender -G40- Special tools and workshop equipment required t  Portable multimeter -V.A.G 1526C- t  Adapter set -V.A.G 1594C- t  121-pin adapter cable -V.A.G 1598/31- Fitting location ⇒ Overview of fitting locations → Chapter

Checking activation The Hall sender indicates the ignition position for Cylinder 1. In the event of failure, the knock control is deactivated and the ignition timing retarded slightly as cylinder assignment is no longer possible. The charge pressure of the turbocharger is also reduced. Even without a signal from the Hall sender the engine will continue to run and can also be re-started: t  When a fault is detected the engine control unit produces one spark per crankshaft revolution for each cylinder. t  The fact that the injection system is one revolution out of phase does not have any noticeable effect on the fuel injection. Instead of taking place when the inlet valves are open, injection is “advanced” (to before the closed inlet valves). This has only a minor influence on the quality of the air/fuel mixture. –  If fitted, push back the rubber grommet of the Hall sender connector but leave the connector plugged in.

–  Connect up the voltage tester -V.A.G 1527 B- between contacts 2 (Hall sender signal) and 1 (positive).   Note The connector contacts are numbered accordingly on the back of the connector. –  Operate starter for a few seconds. t  The LED should flash.   Note Voltage testers with a low current draw do not go out completely between activation signals from engine control unit, but continue to glow slightly and become distinctly brighter on activation. If LED does not flash: check voltage supply. Checking voltage supply –  Unplug the connector at the Hall sender.

–  Connect up the multimeter (voltage measuring range) as follows:

Connector Contact	Measure to
1	Engine earth

–  Switch on ignition. t  Specification: approx. 5 V Checking signal wire –  Connect up the multimeter (voltage measuring range) as follows:

Connector Contact	Measure to
2	Engine earth

–  Switch on ignition. t  Specification: approx. battery voltage Checking earth wire

–  Check for open circuit and short to positive in the following wiring:

Connector Contact	Measure to
3	Engine earth

–  Eliminate open circuit in wiring/short circuit if necessary. If all the readings match the specifications and the light-emitting diode does not flash (measured between contacts 1 and 2 with starter, with connector plugged in): –  Renew Hall sender. If readings do not match specifications, check wiring connections. Checking wiring between Hall sender and engine control unit –  Connect the test box -V.A.G 1598/31- to the wiring harness to the engine control unit, but do not connect the actual engine control unit → Chapter.

–  Check for open circuit and short to earth or positive in the following wiring:

Connector Contact	Test box -V.A.G 1598/31- Socket
1 (positive)	98
2 (signal)	86
3 (earth)	108

–  Eliminate open circuit in wiring/short circuit if necessary. –  If all the test results so far have been OK but a fault related to the camshaft sensor (Hall sender) is displayed again after erasing the fault memory as a test measure, the cause may be as follows: t  Rotor ring on Hall sender out of position –  Unbolt Hall sender, then check to ensure that the rotor ring is correctly aligned on the camshaft. If incorrectly installed, the catch will be pressed flat when the securing screw is tightened. –  If the rotor ring position is OK, check the crankshaft/camshaft assignment. → Rep. Gr.15