• 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.

This ignition system uses an individual ignition coil for each cylinder. The Engine Control Module (ECM) controls the spark events by transmitting the timing pulses on the ignition control circuits to the individual ignition coil in firing order sequence.

• This engine application may use 2 fuses, one for each bank, to supply ignition voltage to the ignition module/coil assemblies. A good indication that a fuse is open is that all misfire counters are incrementing on one side of the engine.
• An open/high resistance on the low reference circuit to the ignition coil may cause a misfire.
• An erratic or weak spark is considered a no spark condition.

Engine Controls Schematics

Master Electrical Component List

Electronic Ignition System Description

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

Control Module References

EL 26792 HEI Spark Tester

For equivalent regional tools, refer to Special Tools.

1. Ignition OFF and all vehicle systems OFF. Disconnect the harness connector at the appropriate T8 Ignition Coil. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 5 Ω between the ground circuit terminal 1/A and ground.
• If 5 Ω or greater
1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, repair the open/high resistance in the ground connection.
• If less than 5 Ω
3. Test for less than 5 Ω between the low reference circuit terminal 2/B and ground.
• If 5 Ω or greater
1. Ignition OFF, disconnect the X3 harness connector at the K20 Engine Control Module.
2. Test for less than 2 Ω in the low reference circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K20 Engine Control Module.
• If less than 5 Ω
4. Ignition ON.
5. Verify a test lamp illuminates between the ignition circuit terminal 4/D and ground.
• If the test lamp does not illuminate
1. Ignition OFF.
2. Test for less than 2 Ω in the ignition circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp illuminates
6. Ignition OFF, exchange the suspect T8 Ignition Coil with the T8 Ignition Coil of a known functioning cylinder.
7. Engine Running.
8. Verify the scan tool Cylinder 1–6 Current Misfire Counter does not increment for the same cylinder that the suspect T8 Ignition Coil was removed from.
• If increments

  Replace the K20 Engine Control Module.

• If does not increment
9. Test or replace the T8 Ignition Coil.

1. Ignition OFF, connect the EL 26792 to the appropriate T8 Ignition Coil.
2. Engine Running.
3. Verify the spark output of the T8 Ignition Coil.
• If no output or the output is weak

  Replace the T8 Ignition Coil

• If the output is good
4. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

• Ignition Coil Replacement - Bank 1
• Ignition Coil Replacement - Bank 2
• Control Module References for engine control module replacement, programming, and setup.