Engine immobilisation (page 2 of 2)

Fuse 1 (C580-2) is connected to the engine Immobilisation warning lamp (C1192-1) by a white/green wire. The lamp is controlled by the Alarm ECU. The warning lamp (C1193-1) is connected to the ECU (C61-11) by a red/slate wire. To illuminate the lamp, the ECU provides an earth. To extinguish the lamp, the ECU provides a feed equal to that provided by fuse 1, creating a 0 volts potential difference. In this way, the ECU can control the flashing sequence of the lamp.

When an ignition feed is received by the Alarm ECU (C61-10), it sends a coded signal (C61-15) to the ECM (C636-26) on a black wire. If the signal does not match the one expected by the ECM, the ECM will immobilise the engine. The Alarm ECU (C57) is also connected to the starter inhibitor/reverse light switch (C69-4) by a black/orange wire.

The Alarm ECU can be interrogated via the diagnostic socket using TestBook. The socket (C40-8) is connected to the ECU (C61-17) by an orange/light green wire.

In addition to the features directly controlled by the Alarm ECU, a passive coil is fitted around the ignition barrel. This is a user friendly way of re-mobilising the engine. The passive coil (C672-1) receives a power supply from the Alarm ECU (C57-7) on an orange/green wire.

The passive coil is only energised when the ignition switch is in position ’II’ and the engine is in an immobilised state. The coil creates a magnetic field that excites a coil in the RF handset. This causes the handset to transmit a code to the Alarm ECU to re-mobilise the engine.