Noteworthy Information

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

A. 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!

B. The dual Hall-effect 18X - 3X crank sensor is the most critical part of the ignition control system. If the sensor is damaged so that the 18X or 3X crank sensor pulses are not generated, the engine will not start!

C. There are 4 circuit wires connecting the crankshaft position sensor to the ignition control module. If there is a problem with any of the four, the engine will not start (no spark and no injector pulses). The circuits are:

^ +10 to 12 volt operating power supply for the Hall-effect switches from the ignition control module.

^ 18X sensor pulse signal to the ignition control module.

^ 3X sensor pulse signal to the ignition control module.

^ Ground circuit for both Hall-effect switches.

Equally important is the crankshaft reference (fuel control) signal generated by the ignition control module. If the PCM does not receive this signal, it will not pulse the injectors.

D. If the 3X crank sensor pulses stop while the engine is running, the engine will keep running. However, it will not restart after being shut "OFF."

E. If the 18X crank sensor pulses stop while the engine is running, the engine will stop running and will not restart.

F. Ignition timing is not adjustable. There are no timing marks on the crankshaft balancer or timing chain cover.

G. If crank sensor replacement is necessary, the crankshaft balancer must be removed first. The balancer is a press fit onto the crankshaft; removing the serpentine accessory drive belt and balancer attaching bolt will allow its removal with special tool J 38197. When reinstalled, proper torquing of the balancer attachment bolt is critical to ensure the balancer stays attached to the crankshaft.

H. If a crank sensor assembly is replaced, check the crankshaft balancer interrupter rings for any blades being bent (runout and concentricity) using special tool J 37089. If this is not checked closely and a bent blade exists, the new crankshaft position sensor can be destroyed by the bent blade with only one crankshaft revolution!

I. Neither side of the ignition coil primary or secondary windings is connected to engine ground. Although the ignition coil packs are secured to the ignition control module, it is not an electrical connection to ground.

J. Be careful not to damage the high tension leads or boots (dust caps) 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 high tension lead or boot for any testing purposes! Future problems are guaranteed if pinpoints or test lights are pushed through the insulation for testing.

K. The ignition module is grounded to the engine block through 3 mounting studs used to secure the module to its mounting bracket. If servicing is required, ensure that good electrical contact is made between the module and its mounting bracket, including proper hardware and torque.

L. A conventional tachometer used to check RPM on a primary ignition "tach lead" will not work on this ignition system. To check RPM, use either of these:

^ A tachometer designed with an inductive pickup, used on the secondary side of an ignition system.

These tachs are identified by a "clamp" that goes around a spark plug wire. Set the tach to "2-cycle" operation. The reason for 2-cycle? Spark plugs on this engine fire every time the piston is at the top of it's stroke. If a "2-cycle" selection is not available, divide the indicated 4-cycle reading by 2.

^ Tech 1 diagnostic tool.