49-State

System Schematics:

Computer Controlled Dwell System H

System Schematics:

Closed Bowl Distributor System H
CONSTRUCTION
Consists of a camshaft driven distributor without centrifugal or vacuum advance, a Powertrain Control Module (PCM), an Ignition Control Module (ICM), a "hall-effect" stator assembly and E-Core ignition coil.

PURPOSE
Designed to ignite the compressed air/fuel mixture supplied to the engine by the fuel and air systems. The ignition system also provides engine timing information to the Powertrain Control Module (PCM) for proper vehicle operation.

OPERATION
How the Profile Ignition Signal (PIP) Is Generated
- The Camshaft (Hall effect) sensor is a digital output device located within the distributor. A rotary vane cup is used to trigger the hall sensor. When the window of the cup is in the air gap between the hall device and the permanent magnet, a magnetic flux field is completed from the magnet through the hall device and back to the magnet.

- This condition results in a low (0 volts) output signal. As the distributor shaft turns, a tooth on the cup will move into the air gap. The magnetic field will be shunted by the tooth, preventing it from reaching the Hall device, and the output signal will change from a low to a high (B+).

Signature Pip Signal
- One tooth on the vane cup is smaller than the rest to identify when cylinder No.1 is at 10 degrees BTDC. The width of the PIP signal generated by this tooth is smaller than that of other teeth and is called signature PIP. It is required by the Powertrain Control Module (PCM) so that it can accurately control the sequential firing of the fuel injectors.

Turning The Coil Primary Circuit OFF
The "rising" edge of the SPOUT signal controls when the coil is turned OFF, thus firing the ignition coil secondary.

Turning The Coil Primary Circuit ON
The "falling" edge of the SPOUT signal controls when the coil is turned ON. The coil ON time, or "dwell" is entirely controlled by the SPOUT signal. The ICM does not internally determine when to turn the coil ON. It responds directly to the SPOUT signal it receives.

SPOUT Signal Failure
In the case that the SPOUT signal line opens from the PCM, the ICM will use the PIP signal to fire the coil. This results in a fixed spark angle and fixed dwell.