Ignition System: Service Precautions
DURASPARK II
Silicone dielectric grease must be applied to all insulating areas of the distributor, spark plug boots, and coil.
When replacing spark plug wires, insure wire made of the same material is used for a replacement. The SS wire is used on cylinders subject to very high engine temperatures.
When removing distributor cap and adapter, always remove the distributor cap first.
Since the electronic control module and ignition coil are on whenever the ignition switch is in the ON or START position, the system will generate a spark whenever the ignition switch is turned off. This may be used as a test tool to check for continuity of circuit, coil and ignition switch. As spark may occur if the distributor cap is removed with switch ON, keep switch OFF during underhood operations until you start the engine or run a test requiring the switch to be on. This will prevent accidental engine rotation.
Maintain a 3/4 inch clearance at distributor cap mounting edge, spark plug wire terminals and coil tower to prevent high voltage arc to ground.
The Duraspark ignition modules are not electrically interchangeable. Duraspark II can be distinguished by having a blue wiring grommet. (Yellow grommet on the Universal Ignition Module.)
When performing diagnostic or service procedures on models equipped with DS II, the ignition switch should remain in the "Off" position unless otherwise stated in the procedure. On these units, a spark will be generated when the ignition switch is placed from the "On" position to "Off", which may inadvertently cause the engine to rotate, resulting in personal injury.
TFI IV
Do not change timing by use of different octane rods without first having the proper authorization as federal emission requirements will be affected.
Except for the cap, rotor, module, O-ring, and octane rod, no other distributor assembly parts are replaceable. There is no calibration required with the universal distributor.
Do not attempt to lift module from mounting surface prior to moving entire TFI module toward distributor flange as you will break the pins at the distributor/module connector.
The rotor is a multi-point rotor which eliminates the need for silicone compound on the rotor tip.
Some engines may be equipped with a security type distributor holddown bolt. Use Tool T82L-12270-A or equivalent to remove the distributor.
CIRCUIT TESTS - TFI IV
The primary winding of the ignition coil may be damaged if there is a short to ground in the wiring harness containing the tachometer circuit. Before replacing the ignition coil due to a no start condition, measure and record battery voltage as well as voltage between coil negative terminal and ground with ignition key in the On position. If there is more than a 1 volt difference between the readings, inspect tachometer circuit for a short to ground and repair as necessary.
If a short to ground is caused by a failed TFI-IV module, the ignition coil primary winding may be damaged. Because this type of malfunction will not be identified using standard testing procedures, the following steps should be taken when servicing a weak or no spark condition: check for spark as described in ``Test 1.'' If there is no spark, test coil primary resistance as described in ``Test 3.'' If coil primary resistance is satisfactory, continue with diagnostic procedure described in ``Test 1.'' If coil primary resistance is not satisfactory, replace coil and recheck for weak or no spark. If spark is now satisfactory, the problem no longer exists. If spark is still not satisfactory, continue with diagnostic procedure described in ``Test 1.''