Ignition Control Module: Description and Operation

PURPOSE
The Thick Film Integrated (TFI) ignition module supplies spark to the distributor through the ignition coil and calculates the duration. It receives its control signal from the Powertrain Control Module (PCM) Spark Output (SPOUT).

DESCRIPTION
The ignition module has six connector pins at the wiring harness that supplies the following signals:
- Run
- Crank (start)
- Tach (coil)
- PIP (crankshaft position to PCM)
- Spark output (SPOUT from PCM)
- Internal ground from the PCM to the distributor

OPERATION
The TFI module receives the PIP signal from the crankshaft sensor, the CID signal from the camshaft sensor, and the SPOUT signal from the PCM.

During normal operation, the PIP signal is sent to the PCM from the crankshaft timing sensor and provides base timing and RPM information.

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).

CONSTRUCTION
The ignition control 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.