Description

Ignition Coils Description

1. Fault Codes:
P1361 Ignition Coil 1 - no ignition coil activation fault
P1362 Ignition Coil 2 - no ignition coil activation fault
P1363 Ignition Coil 3 - no ignition coil activation fault
P1364 Ignition Coil 4 - no ignition coil activation fault
P1371 Ignition Coil 1 - early ignition coil activation fault
P1372 Ignition Coil 2 - early ignition coil activation fault
P1373 Ignition Coil 3 - early ignition coil activation fault
P1374 Ignition Coil 4 - early ignition coil activation fault

2. Monitoring Procedure

Summary
Problems with the ignition coils will be detected using two tests.

The tests work by monitoring the coil current status signal when ignition coils are turned on during normal engine running. The status signal indicates that a threshold coil current has been reached, fully charging the coil. The coils are monitored to detect lack of full charge activation or early activation of the coils, a coil fault event occurring in either case.

If these tests are not passed then appropriate fault count will be incremented, otherwise it will be decremented. If the count reaches a given threshold then a fault is present.

No Activation Test.
If the coil current status signal has not been asserted between the start and end of the coil activation period then there is a coil fault event, as long as engine and battery conditions would normally guarantee that the signal would be asserted. Thus a coil fault event occurs if COIL_CHARGE_EXPECTED flag is set, yet this logic signal was not asserted between the coil turn-on point and the coil turn-off point.

If a coil fault event has occurred, the relevant ignition fault event counter is incremented up to a predetermined limit. If this limit is reached then a no ignition coil activation fault is present. If the ignition coil fault event does not occur after a test then the relevant fault event counter is decremented, down to a limit of zero. When a fault event counter reaches zero then there is no fault present.

Early Activation Test
When the coil is requested to be turned on, if the above coil charge signal is asserted earlier than would normally be expected, then there is a coil fault event. Thus a coil fault event occurs if a measured dwell time is less than the minimum expected dwell time. If the relevant fault counter reaches a predetermined limit then an early ignition coil activation fault is present.

If the ignition coil fault event does not occur after a test then the relevant ignition fault event counter is decremented, down to a limit of zero. When the fault event counter reaches zero no fault is present.

3. Primary Detection Parameter
Primary coil current status provided by the ignition coil drives ASIC, which compares coil current with a fixed (fully charged coil) threshold.

4. Fault Criteria Limits

No Activation Test
The presence or not of coil charge status signal within coil turn-on and turn-off point

Early Activation Test
Minimum expected time to fully charge the coil of 2ms

5. Monitoring Conditions

Lack of Activation Test
There must be a minimum battery voltage of 10 Volts for either test.
There is a maximum engine speed the tests will operate, i.e. 3500 rpm, to allow sufficient coil charge discharge time.

6. Monitoring Time Length / Frequency of Checks
The tests will be run every engine revolution, (double ended coils).

7. Criteria for Storing Fault Code
Two successive trips where the diagnostic routine indicates a failed coil/charging circuit.

8. Criteria for Illuminating MIL
Two successive trips where the diagnostic routine indicates a failed coil/charging circuit.

9. Criteria for Determining Out of Range Input Signals
The coil current status signal is input as a digital high/low signal.