The ignition control module for your 1995 Chevrolet Blazer controls the ignition system's spark advance. Variables, such as engine temperature, load and speed, are a determining factor where spark timing is concerned. In addition to poor performance, reduced fuel efficiency, intermittent or persistent no-start conditions associated with a faulty ICM, the powertrain control module may set a No. 42 diagnostic trouble code or a P0136, depending on the vehicle's on-board diagnostic version. Replacing the ICM is fairly easy, but a little preparation is needed to help ensure the new module lasts for a long time.
Open the hood. Allow the engine to cool, if necessary. When facing the engine from the front of the vehicle, the ignition control module is mounted on the left side of the intake manifold, next to the ignition coil. Disconnect the electrical connector from the ICM.
Remove the two mounting bolts that secure the ICM to the heat sink, using a socket, extension and ratchet. Remove any grime that is present on the mating surface of the heat sink, using a piece of fine steel wool. Lightly spray the mating surface with carburetor cleaner, then finish it off with a clean shop rag.
Apply a uniform layer of heat sink paste to the metallic surface of the replacement ICM. Secure the ICM to the heat sink, then connect the electrical connector to finish the replacement process.
