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Plug
a BNC test lead into channel A on the Scope , place a large black
crocodile clip on the test lead with the black moulding (negative) and
an acupuncture probe onto the test lead with the red moulding
(positive). Probe each of the three connections. The three connections
being: the sensor's voltage supply, an earth and the Hall Effect
output. The Hall Effect output has been monitored in the example
waveform shown on this page.
Fig. 14.1.7.1
Figure 14.1.7.1 shows the fly lead multiplug for the Hall Effect camshaft sensor being probed on a Vauxhall ECO TEC engine.
The time-base may need to be altered if the signal is checked at varying engine speeds.
The
camshaft sensor is sometimes referred to as the Cylinder Identification
(CID) sensor and is used as a reference to time the sequential fuel
injection. The signal waveform can be either a permanent magnetic sine
wave or in this particular case a digital square wave.
The
Electronic Control Module (ECM) needs to see the signal when the engine
is started for its reference; if absent, it can put the ECM into
'limp-home'.
The characteristics of a good Hall effect waveform is clean, sharp
switching and as with all other Hall units has 3 electrical
connections.
Fig. 14.1.7.2
Figure 14.1.7.2 shows
the camshaft sensor in situ. The rotor disc on the camshaft pulley can
clear be seen with the four cut outs that generate the waveform above. |
