Noteworthy Information

There are important considerations to point out when servicing the ignition system. The following Noteworthy Information will list some of these, to help the technician in servicing the ignition system.

^ The ignition coils secondary voltage output capabilities are very high - more than 40,000 volts. Avoid body contact with ignition high voltage secondary components when the engine is running, or personal injury may result!
^ The 24X crankshaft position sensor is the most critical part of the ignition system. If the sensor is damaged so that pulses are not generated, the engine will not start!
^ Crankshaft position sensor clearance is very important! The sensor must not contact the rotating interrupter ring at any time, or sensor damage will result. If the interrupter ring is bent, the interrupter ring blades will destroy the sensor.
^ Ignition timing is not adjustable. There are no timing marks on the crankshaft balancer or timing chain cover.
^ Be careful not to damage the secondary ignition wires or boots when servicing the ignition system. Rotate each boot to dislodge it from the plug or coil tower before pulling it from either a spark plug or the ignition coil. Never pierce a secondary ignition wire or boot for any testing purposes! Future problems are guaranteed if pinpoints or test lights are pushed through the insulation for testing.

POWERTRAIN CONTROL MODULE (PCM)
The PCM is responsible for maintaining proper spark and fuel injection timing for all driving conditions. To provide optimum driveability and emissions, the PCM monitors input signals from the following components in calculating Ignition Control (IC) spark timing:

^ Engine Coolant Temperature (ECT) sensor.
^ Intake Air Temperature (IAT) sensor.
^ Mass Air Flow (MAF) sensor.
^ Trans Range inputs from Transaxle Range switch.
^ Throttle Position (TP) sensor.
^ Vehicle Speed Sensor (VSS).

RESULTS OF INCORRECT OPERATION
An Ignition control circuit that is open, grounded, or short to voltage will set an ignition control circuit DTC. If a fault occurs in the IC output circuit when the engine is running, the engine will experience a misfire. DTCs P0351 - P0358 will set when a malfunction is detected with an Ignition Control circuit. When an Ignition control DTC sets, the PCM will disabled the injector for the appropriate cylinder.

The PCM uses information from the engine coolant temperature sensor in addition to RPM to calculate spark advance values as follows:

^ High RPM = more advance
^ Cold engine = more advance
^ Low RPM = less advance
^ Hot engine = less advance

Therefore, detonation could be caused by high resistance in the engine coolant temperature sensor circuit. Poor performance could be caused by low resistance in the engine coolant temperature sensor circuit.

If the engine cranks but will not run or immediately stalls, "Engine Cranks But Will Not Run" diagnostic table must be used to determine if the failure is in the ignition system or the fuel system. If DTC P0300, P0341, P0342, P0343, P0335, P0336 is set, the appropriate diagnostic trouble code table must be used for diagnosis. Testing and Inspection