Recommended Tools and Equipment
USEA Digital Multimeter DMM (10 megaohm input impedance) . It can safely be used to diagnose and test most vehicle systems.
DON'T USE
Test lights. They are not recommended due to the possibility of damage to the computer or air-bag circuits.
BE PREPARED
Before attempting to diagnose a circuit for an open or a short, it is important that you:
1. Have the proper reference material available:
^ Power Supply Routings
^ Applicable Wiring Diagrams
^ Troubleshooting Information
2. Understand how the system works.
3. Have a good understanding of what condition you are diagnosing:
^ Situation when the problem occurs. (weather, loads, etc.)
^ What systems interact with the one you are diagnosing?
^ Is it intermittent or a consistent problem?
4. Have proper equipment to perform the diagnosis such as a digital voltmeter, alligator clips, and probe leads.