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?

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: power seat works fine but memory does not

A fault such as this is controller related, although the possibility of a wiring fault and/or a program software update would have to be checked. If it is a common issue, the manufacturer might have published a Technical Service Bulletin...

Q: Driver's side windows do not properly function

If removing the driver door window switch (or the driver-side console switch), and applying direct power to the harness yields successful operation of the window, the problem is the switch that was removed for the test. This can be confirmed...

Q: Battery is working and the electrics are not working

From reading your complaint, it sounds like you have plenty of battery power but your engine still won't turn over. If this is the case, then your car may have one of several problems. Other owners have had body control...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...