Skip the auto shop - Our mechanics make house calls

Q: Do wiring harnesses need to be replaced?

asked by on

Do wiring harnesses need to be replaced?

A: As automotive electrical systems increase w...

As automotive electrical systems increase with each model year, so does the amount of wiring required to operate them. BMW says their current models can contain up to a mile of wires weighing as much as 130lbs! All of this wiring acts as the vehicle’s nervous system. Electrical current is carried to perform tasks and electrical signals transmit information to and from computers. Most of the wires are bundled together into groups called harnesses. Harnesses are wrapped in a protective covering and then routed and secured throughout the vehicle to protect them from damage.

But life for vehicles can get tough. Constant vibration, flexing, exposure to heat and cold, water, ice, and salt can all eventually take a toll on the wiring. Wiring harness damage is also not unusual when a vehicle has been involved in a collision.

Many vehicles will go through their entire service life without any issues related to the wiring harness or its connections. But it is not unusual when diagnosing a problem with a vehicle system to eventually locate the root cause at a damaged wire, terminal, or connector. Since wiring harnesses are frequently installed in hard-to-reach locations, finding the exact problem area of the “short” circuit or “open” circuit can frequently be a challenge for a technician.

Once the wire problem is located, typically the damaged wire or two can be repaired, or a new piece of wire can be spliced in. But sometimes the damage is more extensive, wires are melted, or a hard-to-reach location makes repair impossible. In these types of situations an entire portion of harness may need to be replaced. Since harnesses come in all sizes from small and simple, to large and complex, the cost to purchase and install them covers a very broad range. Some vehicle manufacturers also specify harness replacement, rather than wire repair, on certain sensitive safety systems such as airbags. This type of specific guidance varies between manufacturers and can be found in their service information.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Weird electrical issues

The vehicle you have has problems with fretting corrosion in the connections of various modules throughout the vehicle. The problem module connectors should be disconnected, and a dielectric compound put in the connectors to stop the corrosion. The problem is...

Q: My 4.0 engine that I had purchased before blew out and now I can't afford 4.0 engine. Could I replace the engine with small 3.3L, even if performances decrease?

Hi and thanks for contacting Your Mechanic. You can replace your vehicle with any engine size as long as the engine will bolt up to the transmission, the electrical harness will match the engine as it did on the 4.0L,...

Q: If I shut my car off it doesn't restart.

Well the first thing I would check is to see if the alternator is working. I would suspect it would be in the distributor. Ignition module, tdc sensor. A few voltage tests can tell you for sure. I would recommend...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...