Procedure

Verify The Complaint:
Check the complaint. Try to understand the problem. If possible, let the driver show you what happens. Check all functions of the system and note the symptoms before starting any testing or disassembly.

Analyze The Problem:
Identify the part of the electrical system that is most likely to be causing the problem. Find the Circuit Section in the manual that applies to that part of the system. Find the wiring diagram that applies to the vehicle. By following the circuit from a ground (GND) back to the power source, get an understanding of how the circuit works.

Find The Problem:
You will find the problem if you follow a simple and logical step-by-step procedure. Test portions of the circuit one at a time, starting with he area or component most likely to be malfunctioning. Test first at points that you can reach most easily.

Repair The Problem:
When you find the cause of the problem, make the repair. Use appropriate tools and procedures.

Check The Results:
Be sure it works. Check the functions of all parts of the circuit that you worked on.

Working On The Electrical System:
A test light or a multimeter can be very helpful for testing circuits. See Tools and Equipment for more information on test equipment.
Current flow is logical, always moving from the highest potential at the Voltage source (+) toward the lowest potential at ground (-). Using a wiring diagram to trace a circuit, you should start with the ground (GND) and then follow the wires back to the source of power.

To Troubleshoot A Circuit:
1. Inspect all connections, especially grounds (GND). Make sure they are clean, tight and corrosion-free.
2. Check the fuses.

NOTE: Repeated fuse failures are the sign of a malfunctioning wire, a failed component, or a short to ground (GND) somewhere in the circuit.

3. Check for Voltage reaching particular components or points in the circuit.
4. Check continuity between points to look for breaks in the circuit (open circuit).
5. Check Voltage drop at connections, especially ground (GND) connections.