HomeTips & GuidesAuto wiring harness repair: When it is time to replace the complete wiring harness

Auto wiring harness repair: When it is time to replace the complete wiring harness

Auto wiring harness repair: As an integral part of the vehicle, wiring must always remain in working conditions.

However, as cars undergo a lot, the auto wiring harness gets exposed to high temperature, ice, water, and salt conditions and tends to get damaged with time. 

When the wire is damaged, the only solution is to repair or replace it, and everyone tries to fix the harness first for obvious reasons.

It’s for the same reason auto wiring harness repair has become a core competence in the auto industry.

Table of Contents

Causes of auto wiring harness failures:

  • Bend in the harness: Sometimes, due to high mileage, bumpy roads, and adverse weather conditions, the harness wires wear down or grow stiff over time.
  • Exposed wires: Heat, rain, cold, or extreme vibrations break small pieces in the harness, exposing wires. These exposed wires may lead to many faulty conditions.
  • Harness malfunctioning: Some procedure errors during manufacturing, like wrong wire size, incorrect crimping, or improper assembly layout, lead to harness malfunctioning after installation.
Pigtail wiring harness

Pigtail wiring harness

Warning signs of Auto wiring harness failures:

  • Your vehicle’s lights will not operate properly as they get power from the car’s battery.
  • Flickering the vehicle’s lights also indicates wiring issues in your car.
  • Wiring issues may also lead to a dead battery, creating problems while starting the vehicle.
  • If you are experiencing sudden stall or rev along with jerking, lurching, or stuttering, the reason is probably bad wiring.
  • Wiring malfunction also leads to the illumination of the engine light.
Automotive wire chewed

Automotive wire chewed

Repairing/replacing auto wiring harnesses:

A typical auto wiring harness comprises the following components:

  • Connectors
  • Backshells
  • Wire
  • Splices
  • Terminals
  • Contacts
  • Shrink tubing
  • braid/string tie for holding wires

For any wiring malfunction, it is less probable that you will replace the entire harness. When your auto wiring harness fails, find out the reason and then replace only the damaged or affected parts in the harness. 

However, it does not mean that a single harness will last a lifetime after being installed in the vehicle.

You may need to replace the entire harness if the damage is extensive, like melted wires. Also, for sensitive systems like airbags, it is always good to replace the harness completely if any error occurs.

The cost of buying a new wiring harness depends on the size and location of the same.

Sometimes, the damage is so much distributed that replacing it is less expensive than repairing the harness.

So, whether you need to replace or repair the harness depends entirely on the damage size, budget and location of the harness.

Auto wiring harness components 

Auto wiring harness components 

Things to consider of auto wire harness repairs:

The process of auto-wiring harness repair is more complex due to the sensitivity and complexity of the harness.

The small diameter of wires and terminals, restricted space, and networked electronics make it challenging.

Here, we are mentioning a few points that can ease your work to some extent.


Safety always comes first, so disconnect the battery to cut off the power supply when repairing wires. This will keep you and the entire circuit safe from sudden short circuits. 

If you want to do some diagnostic tests and keep the battery running, it’s better to use a test light or multimeter for voltage testing. 

Know the circuit and choose the right connection way.

Nowadays, vehicles carry complex computer-controlled electrical systems, which carry specific components in their construction. You need to know the circuit before starting to repair it. Some circuits have very low voltage signals; too much solder or long splice may lead to signal error due to resistance.

If you need crimp connectors during repairs, get the right size, as too big and too small will cause errors. Also, strip off the required insulation when you install a crimp connector so you do not crimp the wire’s coat. 

Heat shrinks tubing to secure wires:

Black electrical tape is common in vehicle wiring, but don’t use it to protect the repaired part. With high moisture and temperature, it may become loose or may unwrap. Use it only to bundle wires.

Use heat shrink tubing to protect wires from dirt, moisture, and other contaminants, making the solder or crimps more reliable.

Sometimes, professionals use lighters to heat the tube, but we advise you to use a heat gun. Heat gun helps you give the right amount of heat without melting wires and nearby circuits.

When repairing multiple wires, it is good to use heat shrink tubing on individual wires and then use a large tube to bundle all the individual wires together for a neat and reliable result.

Replace the damaged wires with the new ones:

If the damage on the wire is extensive, you are supposed to replace it with a new one.

Break wires carefully out of the harness:

Always be careful while removing a damaged wire from the harness so you do not damage near connectors and wires.

Choose Automotive grade wiring:

Automotive grade wires, a strand type wiring, differ from normal wires as they can handle vehicle vibrations and heat.

Use the correct gauge wires.

Too thin wire may fail during high power surges, while too thick can add extra resistance to the circuit.

While repairing, ensure you use the same spec wire installed earlier. 

You must know that switches, signals, and circuits use different-sized wires; for example, headlights use thin gauge wire while the battery uses a wire with thick gauge.

Don’t forget the voltage drop along with the wire length. So, to combat the voltage drop, you must pick large gauge wires.

Here is a chart that details the wire gauge breakdown concerning amperes and length.

Total wire length in feet
AMPERES10 Amp – 120W16ga16ga 16ga14ga14ga14ga12ga12ga10ga10ga10ga8ga8ga4ga
15 Amp – 180W16ga16ga14ga14ga14ga12ga10ga10ga8ga8ga8ga4ga4ga4ga
20 Amp- 240W16ga14ga14ga12ga12ga10ga10ga8ga8ga8ga4ga4ga4ga4ga
25 Amp – 300W14ga14ga12ga10ga10ga10ga8ga8ga4ga4ga4ga4ga4ga1/0ga
30 Amp – 360 W14ga14ga12ga10ga10ga8ga8ga8ga4ga4ga4ga4ga1/0ga1/0ga
40 Amp-480 W14ga12ga10ga8ga8ga8ga4ga4ga4ga4ga4ga1/0ga1/0ga1/0ga
50 Amp – 600 W12ga12ga10ga8ga4ga4ga4ga4ga4ga4ga1/0ga1/0ga1/0ga1/0ga
60 Amp – 720 W12ga10ga8ga8ga4ga4ga4ga4ga4ga1/0ga1/0ga1/0ga1/0ga1/0ga
70 Amp – 840 W12ga10ga8ga4ga4ga4ga4ga4ga1/0ga1/0ga1/0ga1/0ga1/0ga3/0ga
80 Amp – 960 W12ga8ga8ga4ga4ga4ga4ga1/0ga1/0ga1/0ga1/0ga1/0ga3/0ga3/0ga
90 Amp – 1080W12ga8ga4ga4ga4ga4ga1/0ga1/0ga1/0ga1/0ga1/0ga1/0ga3/0ga3/0ga
100 Amp – 1200 W10ga8ga4ga4ga4ga4ga1/0ga1/0ga1/0ga1/0ga1/0ga3/0ga3/0gaN/A
120 Amp- 1440 W10ga8ga4ga4ga4ga1/0ga1/0ga1/0ga1/0ga1/0ga3/0ga3/0gaN/AN/A
140 Amp – 1680 W10ga4ga4ga4ga1/0ga1/0ga1/0ga1/0ga1/0ga3/0ga3/0ga3/0gaN/AN/A
160 Amp – 1920 W8ga4ga4ga1/0ga1/0ga1/0ga1/0ga1/0ga3/0ga3/0ga3/0gaN/AN/AN/A
180 Amp – 2160 W8ga4ga4ga1/0ga1/0ga1/0ga1/0ga1/0ga3/0ga3/0gaN/AN/AN/AN/A
200 Amp – 2400 W8ga4ga4ga1/0ga1/0ga1/0ga1/0ga3/0ga3/0ga3/0gaN/AN/AN/AN/A

Choose wire colors:

Wire harnesses come with a particular color combination, and keeping the same color coordination during repair will make your future repair convenient.

Terminate the wire to the connector properly.

Ensure connectors and back shells are in good condition:

Check and repair connectors, hoods, and back shells when repairing damaged wires. If these parts remain damaged, repairing wires won’t do anything good.

Automobile harness wire repair

Automobile harness wire repair


Indeed, you cannot know everything about wire repairs, as there are customized harnesses with specific components and circuits.

If, even after several attempts, you fail to repair your auto wiring harness, contact Cloom. We are an expert in all sorts of wiring harnesses and cable assemblies.

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

Background media

For Better Future
and Business
Let’s Talk Now!

Fill in your details and we’ll get back to you in 24 Hours.

Contact Form Demo


[email protected]




3rd Floor, Nanhai Plaza, NO.505 Xinhua Road Xinhua District,
Shijiazhuang, Hebei, China. 050057


© 2007- 2023 Cloom tech. ALL RIGHTS RESERVED.



Subscribe to our newsletter for the latest updates, exclusive offers, and exciting news delivered straight to your inbox.