Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003EXPRESS 1/2 TON VAN V6-4.3L VIN XREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMTESTING AND INSPECTION
2003 Chevrolet Express 1/2 Ton Van V6-4.3L VIN X
Ignition System: Testing and Inspection
2003 Chevrolet Express 1/2 Ton Van V6-4.3L VIN XSECTION Testing and Inspection
DISTRIBUTOR IGNITION (DI) SYSTEM DIAGNOSIS
SYSTEM DESCRIPTION
This system includes the crankshaft position (CKP) sensor, the camshaft position (CMP) sensor, the ignition coil with the ignition control (IC) module, the secondary wires, the spark plugs, and the circuit conductors and connectors.
The powertrain control module (PCM) controls the ignition system. The PCM monitors the input signals from various engine sensors. The PCM controls the dwell of the ignition primary coil, computes the desired spark timing and firing of the ignition system via an IC timing control circuit to the ignition control module.
The Distributor Ignition (DI) System Diagnostic Table assumes the following conditions:
- The battery is fully charged.
- There is adequate fuel in the fuel tank.
- The fuel delivery system is functional.
DIAGNOSTIC AIDS
Engine mechanical conditions may prevent the distributor from rotating. Inspect the following if the distributor rotor does not rotate:
- A broken distributor drive shaft
- A worn or broken distributor drive gear
- A worn or broken camshaft timing chain and gears
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Refer to Diagnostic Aids for Circuit Testing and Wiring Repair Procedures. If a repair is necessary, refer to Wiring Repairs in Diagnostic Aids.
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. This step is testing for a crankshaft position sensor (CKP) signal to the PCM.
4. This step is testing for an internally shorted camshaft position sensor.
9. This step is testing for spark output at more than one spark plug wire. The J-26792 requires a minimum of 25,000 volts to operate.
10. This step determines if spark is being delivered to the distributor cap.
20. This test is testing if the PCM is providing a timing control signal to the ignition control module.
21. This test checks for a basic engine mechanical problem.
SYSTEM DESCRIPTION
This system includes the crankshaft position (CKP) sensor, the camshaft position (CMP) sensor, the ignition coil with the ignition control (IC) module, the secondary wires, the spark plugs, and the circuit conductors and connectors.
The powertrain control module (PCM) controls the ignition system. The PCM monitors the input signals from various engine sensors. The PCM controls the dwell of the ignition primary coil, computes the desired spark timing and firing of the ignition system via an IC timing control circuit to the ignition control module.
The Distributor Ignition (DI) System Diagnostic Table assumes the following conditions:
- The battery is fully charged.
- There is adequate fuel in the fuel tank.
- The fuel delivery system is functional.
DIAGNOSTIC AIDS
Engine mechanical conditions may prevent the distributor from rotating. Inspect the following if the distributor rotor does not rotate:
- A broken distributor drive shaft
- A worn or broken distributor drive gear
- A worn or broken camshaft timing chain and gears
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Refer to Diagnostic Aids for Circuit Testing and Wiring Repair Procedures. If a repair is necessary, refer to Wiring Repairs in Diagnostic Aids.
TEST DESCRIPTION
Steps 1-2:
Steps 3-6:
Steps 7-9:
Steps 10-13:
Steps 14-17:
Steps 18-22:
Steps 23-27:
Steps 28-33:
Steps 34-42:
Steps 43-50:
The numbers below refer to the step numbers on the diagnostic table.
3. This step is testing for a crankshaft position sensor (CKP) signal to the PCM.
4. This step is testing for an internally shorted camshaft position sensor.
9. This step is testing for spark output at more than one spark plug wire. The J-26792 requires a minimum of 25,000 volts to operate.
10. This step determines if spark is being delivered to the distributor cap.
20. This test is testing if the PCM is providing a timing control signal to the ignition control module.
21. This test checks for a basic engine mechanical problem.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.