A multimeter and a few simple tools can be used to test an ATV CDI module (Capacitor Discharge Ignition) box on a Chinese ATV. The steps are as follows: Connect the CDI box to the wiring harness You must first detach the ATV CDI module from the wire harness before you can test it. By doing this, any electrical interference or harm to the wiring harness during testing will be avoided. Check the ATV CDI box by measuring the resistance between its terminals with an ohms-set multimeter. The manufacturer's specifications, which may be found in ATV's service manual, should be met by the resistance. Check the ATV CDI box continuity Check the continuity between the terminals on the CDI box by switching the multimeter to continuity mode. By the service manual's specifications, there must be continuity between particular terminals. Connect the CDI box to an ignition coil and a spark plug to check the output voltage. Check the output voltage from the CDI box when the engine is running using a multimeter set to AC voltage. The voltage must comply with the manufacturer's requirements. Look for indicators of damage or short circuits in the CDI box, such as burned or melted wires or components, and check for them. It's crucial to keep in mind that testing a CDI box needs some technical skill and that ineffective testing might cause additional harm to ATV's electrical system.