Service Bulletins & Newsletters

 Subject:  Solid State Ignition Distributors
 Engine Models :  All 2 & 4 cylinder gas engines
 Service Bulletin #: SPD - 3 - 87 (Revised)
 Date Issued:  February 1988


All new Wisconsin multi-cylinder engines are now being equipped with a solid state ignition distributor. Externally the new solid state ignition distributors are similar in appearance to a conventional point ignition distributor. Internally the major differences are;

1) Distributor cam which opens ignition points has been replaced with a magnet assembly.
2) Ignition points have been replaced with a "Hall effect type" electronic module.

This solid state ignition distributor uses two primary leads which attach to the ignition coil. The black or blue lead connects to the negative (-) terminal of the ignition coil while the red lead connects to the positive (+) side of the ignition coil.

NOTE: The same Wisconsin ignition coil is used on the solid state and point ignition systems. Be aware that this coil has an internal resistor and many aftermarket do not have these feature even though in outward appearance, they look the same.


The following steps should be performed if the engine's ignition system appears to not be operating properly:

1) Visually inspect all plug wires, coil wire, distributor cap and rotor. replace any components that show deterioration. It is especially important that the cap and plug wires be in good condition free of oil, grease and moisture. If wire has a slight cut or nick in it some people put a couple of turns of electrical tape around the wire. This has not effect. To have the proper "dielectric strength" (resistance for current to travel through an object such as electrical tape), you would need to have a couple of inches of tape wrapped around the cut. Replace the wire.

2) Check for loose or poor connections in the ignition circuit. Check battery terminals for corrosion and loose connections.

3) Check battery's voltage with the engine off. It should be between 12 - 15 volts.

NOTE: The ignition timing adjustment specifications and procedures for the sold state ignition systems are the same as the corresponding point ignition distributor. An automotive type timing light should be used to check and adjust the ignition timing.


Testing can be done either with a voltmeter or a 12 volt test light.


1) Connect the positive (+) lead of a voltmeter to the negative (-) side of the ignition coil. Ground the negative (-) lead of the voltmeter. Set the volt meter to DC volts on at least 15 volt.

2) Disconnect the high voltage wire from the center of the distributor cap and ground it to the engine block or frame of the equipment.

3) Crank engine.

4) The voltmeter should fluctuate from a range of 1 - 2 volts to a range of 10 - 12 volts as the engine is cranked.

NOTE: On some voltmeters the needle will appear to bounce between 1 - 12 volts.

5) If the voltmeter does not fluctuate, one of the following problems exist:

a) If the voltmeter shows a constant "0" reading, there is an open circuit somewhere in the primary ignition circuit.
b) If the voltmeter shows a constant voltage in the 1.0 - 3.5 volt range, the electronic module is shorted out.
c) If the voltmeter shows a constant voltage equal to the battery voltage, the electronic module has an open circuit and requires replacement.


1) Connect the test light between the positive (+) side of the ignition coil and ground. With the ignition switch in the "on" position the light should light.

NOTE: If there is no voltage present at the positive side of the coil, recheck the circuit from the battery through the ignition switch to the coil.

2) Disconnect the black primary lead going between the ignition coil negative (-) terminal and the distributor. Connect the test light to the negative (-) terminal of the ignition coil.

3) Disconnect the high voltage wire from the center of the distributor cap and ground to the engine.

4) Crank the engine.

5) The test light should flicker as the engine is cranked.

6) If the light does not flicker then the distributor electronic module is faulty.

Click pic for larger view

Parts Information

For a complete listing of all parts available for the various ssi distributors go here.


NOTE: To avoid damage to the distributor components the following conditions must be avoided;

1) REVERSE POLARITY - Do not reverse the main battery cables or the wires from the distributor to the coil even for a second. This distributor is negative ground only. The black coil lead goes to the negative (-) terminal of the coil; the red lead goes to the (+) terminal of the coil.

Some early production distributors have a blue lead instead of a black lead for the negative coil lead.

2) VOLTAGE SURGES - Do not operate the engine with the battery disconnected. Insure all electrical connections are made properly. Avoid using switches on the engine which cause excessive arcing.

3) ALWAYS DISCONNECT the battery ground (negative) cable when charging the battery.

4) JUMP STARTING - Only use another 12 volt battery for jump starting. Be sure the battery polarity is correct (positive to positive, negative to negative).



| home | contact us |

Copyright (2003) WMC  Last updated 04-27-05