Please read before installing the ignition system
The Unimog ignition system module is designed to run on 24 volts, the coil assembly runs on 12 volts, which is why the red wire is connected to one battery. The system does not draw current if the key is on and the engine is not running. The yellow wire is connected to ignition switched 24 volts.
Do not substitute spark plug wires, the wires included are spiral-wound at 800 ohms per foot. Deviating from this wire could damage the module. Replacement wires are available at
The black wires are ground wires, and it is critical that the ground connection is good. A bad ground connection will result in poor performance or failure to start.
The charging system of the Unimog and the batteries must be in good condition, as you are adding a voltage sensitive computer.
The Unimog module will NOT operate on a converter (24 to 12 volt) because the sine wave is not smooth enough. The module must be connected to 24v battery voltage. The module is a voltage sensitive computer that will not tolerate variations in voltage that a converter normally provides. The coil pack should work OK on a converter instead of the single battery connection, as coils are transformers that are much more forgiving to choppy sine waves. Proper operation, however, is not guaranteed due to variations in converter quality. The battery is the best choice.
The red LED that lights up at TDC is next to the optical pickup, see the photo. Your module design may vary, but the LED location is basically the same.
Enclosed are 3 bolts with oversided nuts. The nuts are spacers that go between the coil pack and the vehicle frame. The longer bolts will take the place of the original bolts that held the coil in place.
Proper battery connection for the red wire is shown in the photo.
Do NOT grease the elbow boots where the plug wires connect to the coils. Proper stability depends on a friction fit, if you grease the boots the elbows will pop off at any time. Grease only the spark plug boots. A spare spring is included in case you damage one.
The vacuum port that fed the old distributor must be blocked at the source, if applicable. A vacuum plug is provided.
TDC must be verified before setting the timing. Do not advance the timing, set it at zero degrees, as this is the reference point that the computer works from. Timing advances as soon as the engine starts. When setting the timing the piston in #1 cylinder can be at either the top of the compression stroke or the exhaust stroke, it makes no difference, as the plug fires at both postions, during every crankshaft revolution.
The UnimogSSI is a waste spark system. 2 plugs always fire at the same time, 1 and 6, 5 and 2, 3 and 4. If you lose one plug you will lose the other, as one plug is the return path for the other, and the engine block is the conductor. Therefore, make sure the spark plugs are firmly connected and gapped to factory specs.