GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Monte Carlo 🢒 Engine 🢒 Engine Controls - 3.5L 🢒 Electronic Ignition (EI) System Diagnosis

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Description

There are 3 dual-tower ignition coils that are part of the ignition control module (ICM). The ICM contains coil driver circuits that command the coils to operate. The ICM has the following circuits:

    • An ignition voltage circuit
    • A ground
    • An ignition control (IC) 1 control circuit for the 1-4 ignition coil
    • An IC 2 control circuit for the 2-5 ignition coil
    • An IC 3 control circuit for the 3-6 ignition coil
    • A low reference circuit

The engine control module (ECM) controls each dual-tower ignition coil by transmitting timing pulses on the ignition coil control circuit to the ICM for the proper coil to enable a spark event.

Diagnostic Aids

Inspect the spark plug wires for proper orientation.

Reference Information
    •  Electronic Ignition (EI) System Description
    •  Ignition System Specifications

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Controls Connector End Views
    •  Engine Control Module Connector End Views

Electrical Information Reference

    •  Electrical Center Identification Views
    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Special Tools Required

    • J 26792 Spark Tester
    • J 43244 Relay Puller Pliers

Circuit/System Testing
  1. With the ignition OFF, remove the fuel pump relay using the J 43244 .
  2. Crank the engine and test for a strong spark on each cylinder spark plug wire using the J 26792 . Ground the companion cylinder spark plug wire of each cylinder when it is tested.
    3. ⇒If a strong bright blue spark is present on all 6 of the cylinders, remove and inspect all of the spark plugs for proper torque, proper gap, wear, damage, and fouling. Refer to Spark Plug Replacement , Spark Plug Inspection , and Ignition System Specifications . Replace the spark plugs if necessary.
    ⇒If there is no spark on any of the cylinders, test the ignition voltage circuit of the ICM for an open/high resistance or short to ground, or test the ground circuit of the ICM for an open/high resistance, or a faulty ICM.
    ⇒The wire circuit resistance should measure less than 3 ohms.
    ⇒If spark is present on one or more of the cylinders, inspect and test the spark plug wires for arching, cuts, rubbing on other components, and proper resistance , refer to Spark Plug Wire Inspection and Ignition System Specifications , or a faulty ICM.
    ⇒If all tests are normal, then the system is operating correctly.

Component Testing
    • With positive polarity to the low reference terminal, measure for 9,000-11,000 ohms at 20-23°C (68-74°F) room temperature between each of the ignition coil control terminals and the low reference terminal of the ICM.
       ⇒If the resistance is not within the specified range, replace the ICM.
    • Measure for 7,000-15,000 ohms at 20-23°C (68-74°F) room temperature between each pair of coil towers on the ICM.
       ⇒If the resistance is not within the specified range, replace the ICM.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Spark Plug Wire Replacement for spark plug wire replacement
    •  Spark Plug Replacement for spark plug replacement
    •  Control Module References for ignition control module (ICM) replacement, setup, and programming