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This article explains how to test your Ducati CDI (capacitive discharge ignition), sometimes called the electronic box, or black box.

Note: if there is evidence of melted resin and an odd smell, the coil is bad. Replace it.

The black box has as inputs, four wires: green, white, red and yellow/black. These make up the primary coil. Two spark plug wires are its output. These are the secondary coil. Check to make sure all connections to the coil are secure.

As part of the redundancy built into the 582 ignition system, one pair of charging coils in the stator outputs its AC current via green wires, the other pair via white wires; each black box receives one green and one white wire. The charging coils in the stator may be tested by disconnecting the green and white wires from the coil, and touching the meter leads to the wires. Resistance should be 230 - 280 ohms.

The black/yellow wire grounds the unit via the ignition switch. When the switch is on BOTH, both units are grounded and the system is operating. When the switch is on RIGHT, the connection to that wire is open, so only the other unit (LEFT) is still connected to ground, and operating; when the switch is on LEFT, only the unit connected to RIGHT is grounded and operating. When the switch is OFF, both connections are open, neither unit is grounded, and the system is not operating. The ignition switch can be tested without disconnecting the black/yellow wires, and with the master switch off.

The signal to fire comes into the box via the red wire. This wire originates at the corresponding pickup located inside the magneto. As the magneto trigger rotates past the pickup, the signal to fire travels from the pickup to the black box, and (hopefully) the spark plugs fire. There is redundancy here as well: each spark plug fired by the black box is located in a different cylinder. The pickup may be tested by disconnecting the red wire from the coil, touching one lead to the red wire and one to ground. Depending on the style pickup, resistance will be 50 to 70 ohms (old style) or 140 to 180 ohms (new style).

How to Test the Primary Coil Edit

The black box may be tested by disconnecting the wires, and using a digital multimeter to check resistance between pairs of wires.

Be sure the red test lead is plugged into the Volts - Ohms - Diode terminal, and the black lead is plugged into Common.

Be sure the dial is set to the appropriate range for each test. If you do not get the value you expect, try another range.

Turn the meter on. It should read 1.0 (open). Touch the leads together. It should read 0 (shorted).

Because of the diodes in the primary coil circuit, and the small amount of current produced by the meter, the readings will be different testing the same two wires with the leads switched. Diodes only allow current to flow in one direction.

Use the following chart to organize your results. (insert chart)

How to Test the Secondary Coil Edit

To test the spark plug leads, disconnect the spark plug wires at the coil and put one test lead into each terminal on the black box. Alternatively, you may remove the spark plug caps from the spark plugs, REMOVE THE CAPS FROM THE WIRES, and insert one test lead into the center of the wire. The caps must be removed whether they are resistance caps or not.

Use the 20K scale on your multimeter. You should get a reading of 5100 to 6300 ohms across the outputs.


Part 58 CPS


Rotax Repair Manual for engine type 462 - 532 - 582 UL, edition 10 1994, part number 899 081, Bombardier-Rotax GmbH, page 61-64

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