Knock Sensor (KS) (Engine management system - V8)

It is possible to test both primary and secondary coils of the ignition coils for resistance using a multimeter as follows: l Expected primary coil resistance: 0.5 ± 0.05 Ω at 20 °C (68 °F). l Expected secondary coil resistance: 13.3 ± 1.3 kΩ at 20 °C (68 °F).

The ECM provides the earth control for each coil on separate pins as follows:

LH Bank (cylinders 1, 3, 5, 7) l Cylinder 1 - pin 6 of connector C0638 of the ECM multiplug. l Cylinder 3 - pin 2 of connector C0638 of the ECM multiplug. l Cylinder 5 - pin 8 of connector C0638 of the ECM multiplug. l Cylinder 7 - pin 7 of connector C0638 of the ECM multiplug.

RH Bank (cylinders 2, 4, 6, 8) l Cylinder 2 - pin 2 of connector C0638 of the ECM multiplug. l Cylinder 4 - pin 7 of connector C0638 of the ECM multiplug. l Cylinder 6 - pin 6 of connector C0638 of the ECM multiplug. l Cylinder 8 - pin 8 of connector C0638 of the ECM multiplug.

The ignition coil can fail the following ways or supply incorrect signal: l Coil open circuit. l Short circuit to vehicle supply. l Short circuit to vehicle earth. l Faulty component.

In the event of ignition coil failure any of the following symptoms may be observed: l Engine misfire on specific cylinders. l Engine will not start.

Knock Sensor (KS)

The ECM uses two knock sensors located between the centre two cylinders of each bank to detect pre-ignition. The knock sensors consist of piezo ceramic crystals that oscillate to create a voltage signal. During pre-ignition the frequency of crystal oscillation increases, which alters the signal output to the ECM. The ECM compares the signal to known signal profiles in its memory. If pre-ignition is detected the ECM retards ignition timing for a number of cycles. If no more pre-ignition is detected, the timing is gradually advanced to the original setting.