GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Vivant 🢒 DTC 🢒 DTC 041, 042, 063, or 064

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC 041: Ignition Coil 2 and 3 Control Circuit High Voltage

DTC 042: Ignition Coil 1 and 4 Control Circuit High Voltage

DTC 063: Ignition Coil 2 and 3 Control Circuit Low Voltage

DTC 064: Ignition Coil 1 and 4 Control Circuit Low Voltage

Circuit/System Description

Ignition 1 voltage is supplied to the ignition coil. The engine control module (ECM) provides a ground for the ignition coil (IC) control circuits. When the ECM removes the ground path of the ignition primary coil, the magnetic field produced by the coil collapses. The collapsing magnetic field produces a voltage in the secondary coil which ignites the spark plugs. The sequencing and timing are controlled by the ECM. The ignition coils consist of the following circuits:

    • The ignition 1 voltage
    • The IC 1 and 4 control
    • The IC 2 and 3 control

Conditions for Setting the DTC

041

    • The ECM receives voltage greater than 12 volts through the electronic spark timing (EST) B line while reference pulses are received by the ECM from the crankshaft position (CKP) sensor.
    • This error occurs over 6 times.
    • The DTC runs continuously when the above conditions are met.

042

    • The ECM receives voltage greater than 12 volts through the EST A line while reference pulses are received by the ECM from the CKP sensor.
    • This error occurs over 6 times.
    • The DTC runs continuously when the above conditions are met.

063

    • No voltage is supplied by the ECM through the electronic spark timing B line while reference pulses are received by the ECM from the crankshaft position sensor.
    • This error occurs over 6 times.
    • The DTC runs continuously when the above conditions are met.

DTC 064

    • No voltage is supplied by the ECM through the electronic spark timing A line while reference pulses are received by the ECM from the crankshaft position sensor.
    • This error occurs over 6 times.
    • The DTC runs continuously when the above conditions are met.

Reference Information

Schematic Reference

Engine Controls Schematics

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Engine idling, observe the DTC information with a scan tool. DTCs 041, 042, 063, and 064 should not set.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the ignition coil.
  2. Ignition ON, test for battery voltage between the ignition 1 voltage circuit terminal B and ground.
    3. ⇒If less than B+, repair the ignition 1 voltage circuit for a short to ground or an open/high resistance.

    Important: Set the DMM to the AC Hertz scale for this test.

  3. Connect a DMM between the appropriate ignition control circuit and ground.
    4. • Ignition Coil 1 and 4 control terminal C
    • Ignition Coil 2 and 3 control terminal A
  4. Engine cranking, test for greater than 3 Hz between the appropriate ignition control circuit and ground.
    5. ⇒If less than the specified range, test the ignition control circuit for a short to voltage, short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  5. If all circuits test normal, test or replace the ignition coil.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Ignition Coil Replacement
    •  Control Module References for engine control module replacement, setup, and programming