Having issues with your car's electrical system can be frustrating and expensive to fix. However, many common wiring problems can be repaired yourself for very little money. In this guide, I will walk you through the steps to diagnose and fix the most common wiring issues in your car for less than $20.

Gather Your Supplies

Before getting started, you will need to gather a few basic tools and supplies. Here is what I recommend having on hand:

Diagnosing Wiring Issues

Before you can fix the wiring, you need to diagnose where the problem exists. Here are the main steps I take to track down the fault:

1. Reproduce the Problem

First, try to replicate the exact conditions that trigger the wiring fault. Does a certain light fail to activate when you turn on the headlights? Does the stereo cut out when you go over bumps? Reproducing the issue will help you isolate the problem area.

2. Check Fuses

One of the easiest things to check is the fuse box. If a fuse has blown, it can cause all sorts of odd electrical issues. Replace any burnt out fuses and test the circuit again.

3. Visually Inspect Wires

Carefully examine any visible wires under the dash, along trim panels, and leading to components for damage. Look for rubbed through or cracked insulation, corroded terminals, loose plugs, etc.

4. Use a Multimeter to Check Voltage

Test power and ground at both ends of suspect circuits with a multimeter. This will help you pinpoint any wiring breaks or bad connections that are causing voltage drops.

5. Perform Continuity Tests

Use the continuity function on your multimeter to verify electrical continuity and connections from end to end in questionable wires and circuits.

Common Wiring Repairs

Replace Damaged Wiring

If you find wires with cracked or melted insulation, these can be repaired by cutting out the damaged section and splicing in new wire using heat shrink butt connectors. Soldering makes the most reliable connection when splicing automotive wiring.

Reconnect Loose Wires and Terminals

Over time, vibration can cause wire terminals to come loose from plugs and components. Carefully remove any loose connectors and reconnect them properly. If the terminal is damaged, cut it off and crimp on a new spade connector.

Fix Broken Wires

Wrap each side of a broken wire in electrical tape to prevent shorting, then twist the ends together tightly and cover with heat shrink tubing. For extra strength, also solder the connection.

Clean Corroded Wiring

Battery terminals and engine wiring are prone to corrosion. This can cause high resistance and voltage drops. Clean any corrosion off using a wire brush or sandpaper, then apply dielectric grease to prevent future corrosion.

Repair Fraying Wires

Use electrical tape to wrap and reinforce any wiring with damaged insulation that is exposing bare wire. Wrap the tape tightly around the wire, overlapping about 50% with each pass.


With a few basic tools and inexpensive supplies, you can troubleshoot and repair many common car wiring issues yourself. Just take the time to properly diagnose the problem, then make high quality repairs. Pay close attention to recreate original wire routings and connector orientations during reassembly. Following the techniques outlined here will have you back on the road in no time without breaking the bank.