Cadillac 19179581 Distributor Ignition Control Module Assembly

The ICM is mounted on the top part of the 4.6L rear camshaft cover and is responsible for the following functions In addition to monitoring ON-OFF pulses from the crankshaft and camshaft position sensors, is responsible for generating a camshaft reference signal for controlling the ignition and fuel injection as well as providing the PCM with a ground reference and allowing the PCM to vary the amount of spark advance. The ICM is nonrepairable, and when replacing the module, the remaining components are transferred to the new one. To perform the removal of the ICM, spark plug wires and four electrical connectors must be disconnected, four bolts illustrated in the steps that hold the module to the rear camshaft cover must be unbolted, module assembly has to be taken out of the vehicle and ignition coils removed from the assembly. Last of all, unscrew the ICM from the assembly bracket. The steps for installation are the reverse of the steps for removal.

The HEI module functions as an electronic ON/OFF switch that regulates the current flow in the primary winding of the ignition coil, inducing a high voltage in the secondary winding, which is then directed through the rotor and secondary leads to ignite the spark plugs.

The initial step is to disconnect the tachometer lead (if equipped) at the distributor and then check for a spark at the coil and spark plug wires.

To remove the module, first take off the distributor cap and rotor, then unscrew the module attaching screws and carefully lift the stamped sheet metal shield along with the module out of the distributor. Disconnect the leads from the module, ensuring to observe the color code to avoid interchanging them.

The ICM performs several functions, including monitoring ON-OFF pulses from the crankshaft and camshaft position sensors, creating a camshaft reference signal for ignition and fuel injection control, providing a ground reference to the PCM, and enabling the PCM to control spark advance.