Wiring: An Increasingly Critical and Complex Component in Collision Repair
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Wiring: An Increasingly Critical and Complex Component in Collision Repair

In the 1960s, the wiring harness for a typical car just needed to power the lights and horn, so it only weighed around 10 lbs. Today, a luxury vehicle with all the modern convenience and safety features along with electronic control systems for the engine and drive system has a wiring harness that can weigh over 100 lbs. To get everything in working order after an accident, technicians must do a lot of work using diagnostic tools and visual inspections to make sure all of that wiring is in working order.

Problems with Wires

While you’d expect damage to backup sensors and radar systems because they’re on the ends of the vehicle, even a minor fender bender can damage the wiring. Bending sheet metal can slice through wires, and deformed mounting points can stretch the wires or detach them from mounting points. Abrasion and heat can destroy the insulation, leading to shorts, and minor damage to wires and connectors can cause systems to function intermittently as the wires connect and disconnect over every bump.

Hobbyist vs. Professional Tools

Since 2007, all vehicles sold in the U.S. use OBD-II connectors and CAN Bus communications standards. This lets DIY enthusiasts buy simple diagnostic scanners to diagnose problems, but these are limited to industry-wide standard codes, covering common problems like cylinder misfires.

Professional scan tools connect to the same ports, but they have far more comprehensive testing abilities. These are built to handle manufacturer-specific protocols and codes, giving the technician a complete picture of the vehicle’s electrical system. With new features being added at a rapid pace, the manufacturers of these tools issue frequent software updates to keep up with new vehicles.

Interpreting Results

Even if you had access to a professional scan tool, that doesn’t mean you’d be able to isolate and fix a wiring problem. Let’s look at a problem you might be able to fix on your own: your check engine light comes on, and you stop by your local parts store, so they connect a code reader to your car. It says it’s a problem with the O2 sensor. That means you should replace the sensor, right? Not necessarily. There are several reasons this code will show up:


  • Vacuum leaks
  • Restrictions in the fuel filter or lines throwing off the air/fuel mixture
  • Failure of related sensors that aren’t creating an error code but are throwing off air/fuel calculations.
  • Engine misfires, which lead to oxygen passing straight through the cylinder past the sensor.
  • Damage to the wiring between the O2 sensor and the ECU.


That’s just for one sensor that does one job. When a technician is checking electronic systems before and after bodywork, they’re dealing with sensors and actuators that may handle several jobs for several interconnected systems. For example, an electronic throttle doesn’t just open and close according to how much you’re pushing the gas pedal. It also works with the cruise control system, the traction control system, and user preferences set using dash buttons or the infotainment system. Starting with the error code, the technician checking continuity, measures voltage changes and visually inspecting devices for damage to eliminate possibilities until the malfunctioning component is isolated. Even if all it takes to fix a problem involves nothing more than replacing a wire or soldering a loose connection, it takes a lot of time and skill to find out exactly what needs to be done. However, correct diagnosis can save money by fixing the problem directly instead of trying to solve issues by replacing costly but still functional components.

These repairs can also lead to delays when repairing your vehicle. Sometimes, the vehicle needs to be test-driven to let the system check for problems and to locate intermittent issues. That means that the full extent of the damage can’t be identified until the vehicle has been repaired to the point that it can be driven.

If You Want Collision Repair Done Right, Go to Merton Auto Body 

We may be one of the oldest businesses in Lake Country, but that doesn’t mean we’re behind the times. As an I-CAR Gold Class shop, our technicians constantly receive training on the latest automobile advances, so we can repair your car correctly the first time. Our collision repair shop is just a few miles northwest of Pewaukee, up the road from Ironwood Golf Course.


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