Ignition Control Module: Description and Operation

Dual Plug DIS Module:

PURPOSE
The Distributorless Ignition System (DIS) module performs the following important functions:

- provides a ground for the ignition system through two of the module mounting screws

- selects which ignition coil within the coil pack to fire

- contains solid-state electronic switches that control current to the coil primary circuits within each coil pack

- limit current flow in each coil primary circuit to a maximum of 5.5 amps

- generate the Ignition Diagnostic Monitor (IDM) signal; this provides diagnostic information about the ignition system to the Electronic Control Assembly (ECA).

- provide Failure Mode Effects Management (FMEM) operation.

CONSTRUCTION
The DIS ignition module is a thick film integrated design. The module contains a ceramic substrate thick film assembly and three output drivers mounted on a metal base plate and potted in a plastic housing.

OPERATION
The DIS ignition module receives the PIP signal from the crankshaft sensor, the CID signal from the camshaft sensor, and Spark Output (SPOUT) signal from the ECA. During normal operation, PIP is sent to the ECA from the crankshaft timing sensor and provides base timing and RPM information. The CID signal provides the DIS ignition module with the information required to synchronize the ignition coils so that they are fired in proper sequence. The SPOUT signal contains optimum spark timing and dwell time information. Spark angle is determined by the rising edge of SPOUT, while the falling edge of SPOUT controls the coil current "ON" or "DWELL" time. The dwell time is controlled or varied by varying the duty cycle of the SPOUT signal. This feature is called Computer Controlled Dwell (CCD).