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Understanding the importance of proper wiring repairs

Monday, May 7, 2018 - 07:00
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Having worked in the automotive field for 30-plus years, I’ve seen a considerable amount of change. The biggest changes have come in the form of electronic advancement. When I started working on cars, there was nothing to protect connections from the elements. Today the majority of connectors have some form of protection from moisture. Those that don’t are interior to the vehicle and are only subject to moisture from spills or leaks. I’d like to discuss proper wiring repair and connector replacement. To understand this better requires an understanding of what has gotten us to this point. 

Why the big change? In the early days, large connectors and wires were used; this helped with current flow. When resistance increases and you had a voltage drop that caused half an amp of current loss in a headlight, the change in light output was not really noticed. As electronic ignition and fuel injection came on, the need for more sensors and wires was needed. As features were added to vehicles, wires, switches, relays and modules needed to be added to allow the features to function. At the same time cars were getting smaller, so space also became a concern. To combat the added weight from wires, vehicle emissions gave us communication networks. 

(Photos courtesy of Shaun O'Neill - Mobile Auto Solutions) Connector repaired with RTV instead of a new connector

With these networks, modules could send and receive information and command signals between each other using a minimal amount of wire. As an example, a driver window switch may have needed multiple wires to operate relays and motors for windows; however, a door module could now have a single wire that split and went to all the other doors. Now each door module talking on a single wire network could send requests for the windows to be raised or lowered, the locks to be actuated or the mirrors adjusted. Today, we can have 30-plus electronic control units (ECUs) on a vehicle. All the computers talk to each other via some form of network such as controller area network (CAN), local interconnect network (LIN) or Ethernet. When you start your car, you push a button or turn a key. This action is a request to a module. That module in turn looks at data to see if that request should be ignored or sent to the other modules. Seems fairly simple, right?  

In reality, when you are driving down the road and a tire loses traction, for example, the antilock brake system (ABS) module talks to the powertrain control module (PCM), electronic power steering (EPS) and supplemental restraint system (SRS) to determine a course of action to keep the vehicle driving down the road and not spinning out. Now, I’d like you to think about what could be involved in an advanced driver assistance system (ADAS) event. To avoid steering out of a lane when someone is tired or texting, sensor data that is gathered by multiple computers is shared via network so that a decision can be made in a fraction of a second. Or, like in the commercials, a child runs into the street, and the vehicle stops before hitting them. 

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