|
Knock Sensor
Objective:
Check operation of the knock sensor.
Measurement:
Plot of voltage at the signal output of the knock sensor.
Preparation:
Switch off the engine and ignition.
Connections:
|
INPUT A
|
COM/TRIGGER
|
INPUT B
|
|
Connect the red measurement lead to pin 1 (A) of the plug
connector to the knock sensor. Connect the black ground lead to pin
2 (B).
|
|
|
Procedure Tech 31:
| 1. |
Download the Reference curve. |
| 2. |
Use a metal object (e.g. a hammer) to strike the
engine block in the vicinity of the knock sensor. Regardless of the
engine type the following areas are particularly suitable. Below
the bolt used to fasten the alternator to the engine block, flat
surfaces on the engine block at the front or rear and the engine
mounting (use a metal extension if necessary). |
Note: For some cars
it is difficult to connect the measurement leads to the knocksensor
connector, in this case it may be easier to remove the knocksensor
from the engine and connect the measurement leads directly to the
knocksensor itself. Then the knocksensor can be activated by gently
hitting the knocksensor on a plane surface.
|
Reference Curve:
The signal frequency
of the knock sensor depends on various criteria and cannot be used
to assess the operation of the sensor.
It can be assumed that the knock sensor is working properly,
when the signal plot is an attenuated oscillation.
The amplitude is directly dependent on the impact magnitude and
can likewise vary within broad limits.
|
|
Procedure Tech 32:
| 1. |
Download Setup file (the Tech 32 uses only Setup
files, no reference curves). |
| 2. |
Use a metal object (e.g. a hammer) to strike the
engine block in the vicinity of the knock sensor. Regardless of the
engine type the following areas are particularly suitable: Below
the bolt used to fasten the alternator to the engine block, flat
surfaces on the engine block at the front or rear and the engine
mounting (use a metal extension if necessary). |
Note: For some cars
it is difficult to connect the measurement leads to the knocksensor
connector, in this case it may be easier to remove the knocksensor
from the engine and connect the measurement leads directly to the
knocksensor itself. Then the knocksensor can be activated by gently
hitting the knocksensor on a plane surface.
Setup File:
|
Reference Curve:
|
|
The signal frequency of the knock sensor depends on various
criteria and cannot be used to assess the operation of the
sensor.
It can be assumed that the knock sensor is working properly,
when the signal plot is an attenuated oscillation.
The amplitude is directly dependent on the impact magnitude and
can likewise vary within broad limits.
|
