Understanding the importance of proper wiring repairs

May 7, 2018
What does an acceptable repair consist of? That depends on what is being repaired. Who makes the repair rules, and who is performing the repair. Who performs the wiring repairs in the shop you work at? What is their background? Are they a mechanical technician or a body technician?

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. 

The reason for the quick lesson on the advancement of automotive technology brings us back to protecting connections from the elements. With space being a commodity, engineers have designed smaller modules. While the modules may have shrunk, the amount of electronics could have increased. This required the terminal size to shrink, adding new challenges to connector replacement or terminal repair. When a five-volt supply is used to operate sensors, resistance is extremely critical. Think back to that ADAS event; if the resistance changed for one or more sensors, the data to make decisions has changed. Proper repair of connectors or broken wires has never been more important than it is today. How repairs were made in the past is no longer acceptable. 

(Photos courtesy of Kevin DiVito, Owner of Mobile Auto Solutions) A connector a shop was going to let go

What does an acceptable repair consist of? That depends on what is being repaired. Who makes the repair rules, and who is performing the repair. Who performs the wiring repairs in the shop you work at? What is their background? Are they a mechanical technician or a body technician? Do they have resources for performing the repairs? Efficiency and quality repair involve letting people do what they do best. Having a body man repair a connector for .2 hours and spend 30 minutes is not good business. That means the shop has the choice of having an in-house mechanical tech or subletting the mechanical repairs. How does the tech or shop keep up on technology and repair procedures? Do they attend regular classes or read trade magazines? How do they verify the information they are receiving is correct? Do they have access to OEM service information?  

I was recently at a shop to perform a diagnosis; the in-house mechanical tech replaced a connector. The seals had not been properly crimped so that when the terminals were installed, the seal did not stay seated in the housing. That repair is going to cost someone down the line. The other thing I noticed is that the splices that had been made looked to have been soldered and taped. I see many splice repairs performed this way. While solder has been considered the proper way to make a splice, just taping the repair is not a quality finish. The repaired splice needs to also be protected from the elements. This requires using heat-shrink tubing. Not just any heat shrink will do. To seal the repair from the weather, adhesive lined tubing should be used.   

(Photos courtesy of Mike Van Wazer - Mobile Auto Solutions) The terminal is not sealed, causing 5 volt reference to be missing from the CKP. Cavities of the same connector were left open to the elements.

Another piece of the puzzle is when not to repair. Does the shop or tech have the information or knowledge to know when not to make a repair? I’ve been to many a shop that has made repairs to SRS harnesses that should never have been made. I’ve also seen outside vendors that specialize in wiring repairs who perform connector replacement or splices on harnesses where the OEM states the harness should be replaced. Most of the time I hear the shop say that it’s because the insurance company makes them perform the repair or denies a harness replacement. The OEM has the final say as to how repairs are to be performed. Everyone is learning and becoming more aware of this after the John Eagle lawsuit in Texas. Having access to OEM repair procedures in the form of a subscription or a vendor that provides repairs is the most reliable way to know what can or can’t be repaired. 

(Photos courtesy of Paul Suitor - Mobile Diagnostics) Example of the crimper, crimp and finished splice FCA suggests

In the litigious society we are living in, shops need to be guarded. This means eliminating liability to every possible extent. Start by finding a company that can service your wiring needs in a timely fashion. Providing quality photos and descriptions to the vendor will help speed the process. Get a company that can source and install the proper connector.  Make splices that are weather sealed. Read service information to determine that the terminals are in the correct location. With the right relationships, a shop’s wiring repair needs can result in better cycle time, higher profits and less chance of the repair returning down the road.

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