1995 AUDI A4 start

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Engine Speed (RPM) sensor -G28,
checking


Note:

The engine speed sender is a combined speed
sender and reference mark sender. Without a
signal from the Engine Speed (RPM) sensor -
G28 the engine cannot be started. If the signal
from the Engine Speed (RPM) sensor -G28 fails
while the engine is running, the engine will cut
out immediately.

Checking Engine Speed (RPM) sensor
Component location of sensor and connector
Page 24
-5 .

- Before carrying out test, make sure that sensor
is correctly installed and firmly seated.

- Disconnect harness connector for Engine Speed
(RPM) sensor (grey connector).
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- Operate starter for few seconds.
The diode test lamp should blink briefly once
every two engine revolutions.

Note:
Diode test lamps with a low current draw
continue to glow faintly between impulses from
the engine control module (rather than going out
completely) and become much brighter when
receiving an impulse.
If the diode test lamp does not flash, test the
voltage supply.

Checking voltage supply for Hall sensor

- Disconnect harness connector from relevant Hall
sensor.

- Switch ignition on.
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If all specifications are reached but the diode test
lamp does not flash (measurement taken
between terminals 1 and 2 without unplugging
connector and while operating starter):

- Replace relevant Hall sensor.
If specifications are obtained:

- Check wiring.

Checking wiring between hall sensor and
engine control module

- Connect VAG1598/31 test box to wiring harness
for engine control module. Do not connect to the
engine control module itself Page 24
-20
.

- Check wiring connection from Hall sensor to engine control module for
open circuit and/or short circuit to B+ or Ground (GND).
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pair&id=AUDI.B5.FU04.28.1