From the lowest-class beater all the way up to a concours show truck, wiring is one of the most important aspects of keeping your truck running. A bad connection or exposed wire can have you walking to your next destination-or worse, watching your pride and joy go up in flames. Over the years, old wiring becomes dry and brittle due to extreme temperature changes and old age. Electrical gremlins are probably one of the most frustrating automotive problems, not to mention broken or split wires that can become a hazardous situation, so the time spent rewiring your truck correctly will keep you on the road instead of stranded on the side of it.
We spoke to the experts at Early Classic Enterprises who deal with wiring systems in classic trucks to come up with some tips on how to install a new wiring system in a typical '67-72 Chevy pickup. Like many, our truck's central nervous system had been cut, spliced, frayed, circumvented, and piecemealed during the last 35 years. Wiring was the next step in this truck's restoration. Troubleshooting problems became an all-weekend ordeal. Replacing the decomposing wiring harness with a new one was definitely in order.
"All of our harnesses are hand-assembled to original OEM specifications to ensure a perfect fit in your classic truck. Wire gauge, length, color, and tape are exactly like the stock original down to the last detail. Our kits have the correct factory connectors, making them easy to install," says ECE's Stan Hammond. "Some harness manufacturers supply universal kits that require a lot of trimming and soldering of end connectors and a finished result that doesn't resemble the original factory wiring. Ours are a direct replacement. Looking at all the wiring may seem a little daunting at first, but the connections are simple push-in plugs and will only install one way so you can't make a mistake. We recommend removing the old harness one section at a time and routing the new harness using the original as a guide."
The following is an overview of the change-out; installing the new harness becomes self-explanatory when you compare its connectors to the original ones.
 Early Classic provided the...  Early Classic provided the specific harnesses for our truck. Depending on your truck's factory options, there could be additional add-on harnesses for a cargo lamp, courtesy door lights, auxiliary fuel tank, etc. |  First and foremost: DISCONNECT...  First and foremost: DISCONNECT THE BATTERY before you touch any existing electrical components. As you can see, many "additions" have been made to the factory wiring on this truck. |  Stan chooses to start at the...  Stan chooses to start at the front and work toward the back. These trucks have a two-harness plug on the driver-side firewall. |