Buick Regal: Electronic Ignition System Diagnosis

Diagnostic Instructions

• Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis
• An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions

Circuit/System Description

For an overview of the component/system, refer to:Electronic Ignition System Description

The ECM controls the spark event for each cylinder through individual ignition coil control circuits.

When the ECM commands the ignition control circuit On, electrical current flows through the primary winding of the ignition coil, creating a magnetic field. When a spark event is requested, the ECM commands the ignition control circuit Off, interrupting current flow through the primary winding. The collapsing magnetic field created by the primary winding induces a high voltage in the secondary winding, which is connected to the spark plugs. The ignition system on this engine uses ignition coils with integrated power transistors.

Reference Information

Schematic Reference

Engine Controls Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index and Inline Harness Connector End View Index

Electrical Information Reference

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

Scan Tool Reference

Control Module References

Special Tools

J-26792 Ignition Spark Tester

Equivalent regional tools: Special Tools (Diagnostic Tools) and Special Tools (Mechanical Tools)

Circuit/System Testing

NOTE: Do NOT perform this procedure unless directed here from the following diagnostic:

• DTC P0300-P0304
• Engine Cranks But Does Not Run

NOTE: It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

1. Ignition/Vehicle & All vehicle systems - Off.

2. Disconnect the appropriate electrical connector:T8 Ignition Coil.

3. Test for less than 10 ohms between the test points: Ground circuit terminal 1/A & Ground

• If 10 ohms or greater.

1. Disconnect the ground connection: Ground terminal
2. Test for less than 2 ohms between the test points: Ground circuit terminal 1/A@Component harness & The other end of the circuit
   • If 2 ohms or greater - Repair the open/high resistance in the circuit.
   • If less than 2 ohms - Repair the open/high resistance in the ground connection.

• Go to next step: If less than 10 ohms

4. Test for less than 10 ohms between the test points: Low Reference circuit terminal 2/B & Ground

• If 10 ohms or greater

1. Disconnect the electrical connector:K20 Engine Control Module
2. Test for less than 2 ohms between the test points: Low Reference circuit terminal 2/B@Component harness & The other end of the circuit
   • If 2 ohms or greater - Repair the open/high resistance in the circuit.
   • If less than 2 ohms - Replace the component:K20 Engine Control Module

• Go to next step: If less than 10 ohms

5. Ignition - On / Vehicle - In Service Mode

6. Verify a test lamp turns On between the test points: Ignition circuit terminal 4/D & Ground

• If the test lamp does not turn On

1. Ignition/Vehicle - Off & Remove - Test lamp
2. Test for less than 2 ohms between the test points: Ignition circuit terminal 4/D@Component harness & Output terminal@Fuse
   • If 2 ohms or greater - Repair the open/high resistance in the circuit.
   • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.

• Go to next step: If the test lamp turns On

7. Test or replace the component:T8 Ignition Coil

Component Testing

With Special Tool

NOTE: Circuit/System Testing must be performed before proceeding with Component Testing.

1. Ignition/Vehicle - Off.

2. Remove the appropriate component:T8 Ignition Coil - Leave the electrical connector connected.

3. Install the special tool: J-26792 Ignition Spark Tester.

4. Engine - Running.

NOTE: An erratic or weak spark is considered a no spark condition.

5. Verify there is spark at the tool.

• If there is no spark

Test or replace the component: T8 Ignition Coil

• Go to next step: If there is spark

6. All OK.

Without Special Tool

1. Ignition/Vehicle - Off.

2. Swap the two components:T8 Ignition Coil - The original component that set the DTC & Another known good component from the vehicle.

3. Engine - Running.

4. Verify the scan tool parameter: Cylinder 1 - 4 Current Misfire Counter=Increments - At the original component location the DTC set.

• If the parameter value does not increment

Replace the component:T8 Ignition Coil - The original component that set the DTC

• Go to next step: If the parameter value increments

5. Refer to: Circuit/System Testing

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification

• Ignition Coil Replacement
• For control module replacement, programming, and setup refer to: Control Module References

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