With Special Tool
CIRCUIT DESCRIPTIONEach ignition coil supplies secondary voltage to a pair of spark plugs. This is called a waste spark ignition system. The powertrain control module (PCM) supplies ignition control (IC) signals to the ignition control module (ICM). The ICM fires the correct ignition coil at the correct time based on the IC signals. The ICM detects if cylinder 1 or cylinder 3 is on the compression stroke by sensing the secondary voltage and polarity of each side of the ignition coil. The ICM detects this voltage with sensing circuitry integrated into each ignition coil. The higher voltage is on the compressing cylinder. the ICM provides a synthesized cam signal to the PCM based on these inputs. This is called compression sense ignition. The PCM uses the cam signals to synchronize fuel injection.
This system consists of the following circuits:
- Ignition 1 voltage
- Ground
- Camshaft position (CMP) sensor signal
- IC timing control-2/3
- IC timing control-1/4
DIAGNOSTIC AIDS
- A small amount of resistance in the battery positive voltage circuit to the PCM may cause a no start. Test the battery positive voltage circuit for excessive resistance or corrosion. Refer to Diagnostic Aids for Circuit Testing and Wiring Repair Procedures.
- The PCM grounds will cause a no start only if none of them are making a good connection. Refer to Diagnostic Aids for Circuit Testing and Wiring Repair Procedures.
- If the crankshaft position (CKP) sensor is loose the sensor may cause an intermittent no start by moving away from the reluctor wheel.
TEST DESCRIPTION
Steps 1-5:
Steps 6-7:
Steps 8-11:
Steps 12-14:
Steps 15-19:
Steps 20-26:
The numbers below refer to the step numbers on the diagnostic table.
4. This step tests for a short to voltage in the ignition circuit.
5. This step tests for a short to voltage in the battery circuit.