This wave form shows the immobiliser signal generated by the BSI (immobiliser), communicating with the engine ECU (S2000), from a 206 HFX 1.1
The signal gererated, shows the basic carrier signal. The coded signal is encrypted in the carrier and is only visible if looked at much faster.
It is a good signal, with no faults. The ECU is connected and working.
This wave form is taken from the same vehicle as above. This signal shows the engine ECU being re-supplied by the BSI, approximately 10 seconds after the ignition is switched off.
You can see the 'lock' signal being generated from the BSI.
For reference; the BSI sends this signal, even with the engine ECU disconnected. It does not, however, send an 'unlock' signal with the engine ECU disconnecetd.
(Also I noted the signal line, with the engine ECU dead or disconnected, shows battery voltage all the time).
The wave form below is that of the Bitron coolant sensor, as used for cooling fan control on many Peugeot vehicles with air conditioning.
This one came from a 306, with no faults. This is a good signal.