Rich’s Repair Ramblings #8: Repairing a ground wire

Rich’s Repair Ramblings #8, Repairing a ground wire

In our most recent previous Ramblings, we stated that “the number one cause of automotive electrical problems is loose, dirty, or corroded connections”. In this installment we’ll show you how to fix a loose or broken terminal connection. On our AACA cars, many electrical terminals are universal, or a standardized size; they have self-described names like ring, spade, blade, and bullet. Making a repair typically involves replacing a short piece of wire, or attaching a new connector to a wire, or both.

The best way to make such a repair is by soldering. However, soldering requires dedicated tools and equipment, and some practice. An alternate method is using solderless terminals, aka crimp terminals, which are quicker and easier than soldering. I’ve been successfully using them for years. They get a bad rap as unreliable, but like most repairs, there’s a correct way, and an incorrect way, to complete the job. Let’s dive in.

First, you’ll need these tools and supplies: wire stripper, terminal crimper, wire, appropriate terminal, and electric tape or shrink wrap. There are some very fancy stripping and crimping tools on the market, but I’ve had the same pair of yellow-handled combo cutters/strippers/crimpers forever, and they still get the job done. For wire, you’ll want the same gauge as the existing wire (gauge number DECREASES as wire thickness INCREASES- if in doubt, bring a sample to the store). For most of my car repairs, 16- or 14-gauge suffices.

L to R: stripping/crimping tool, terminal assortment, homemade test wire

Crimp terminals are color-coded for size: the smallest are red (18-22 gauge wire), then blue (14-16 gauge), and the largest, yellow (10-12 gauge). Again, for cars, blue connectors cover almost all my needs. When buying electrical tape, stick to name brands; I like 3M, which costs a bit more, but makes better repairs. In the example below, I use shrink wrap, which comes in different diameters. You want a diameter which will fit OVER the end of the terminal.

Top to bottom: female spade connector, shrink wrap, 14-gauge wire

For my sample repair, I need a 2-ft length of 14-gauge wire, and need to crimp a (blue) female spade terminal to one end of the wire. Note that I’ve correctly matched the 14-gauge wire to a blue-coded terminal. THE FIRST MOST COMMON MISTAKE IS INCORRECTLY MATCHING THE WIRE AND TERMINAL SIZES. I’ve verified that the shrink wrap fits over the barrel end of my terminal. I will strip about 3/8” of insulation from the wire – enough so that when the stripped end is inserted into the terminal, a tiny bit peeks out, and bare copper is under the barrel where I will be crimping. THE SECOND MOST COMMON MISTAKE IS STRIPPING TOO LITTLE INSULATION SO THAT BARE COPPER IS NOT UNDER THE TERMINAL BARREL.

Stripping the wire

When using the stripping tool, select the opening which is just slightly smaller than the wire diameter. Your goal is to cut the insulation so that you can pull it off without also removing any copper strands. I took the photo using the 2nd-smallest size, but then ended up moving the wire to the next larger size. This takes some practice – try it out on several different wire gauge sizes.

Before crimping the terminal, slide the shrink wrap onto the wire; if you’re repairing an existing wire on the car, this may be your only chance to get it into position! With the terminal placed over the bare copper strands, verify that copper is under the barrel, Use the crimping part of the tool to firmly crush the barrel onto the wire. THE THIRD MOST COMMON MISTAKE IS CRIMPING THE TERMINAL NEAR ONE OF ITS ENDS SO THAT THE CRIMP DOESN’T FIRMLY GRASP THE WIRE. A COROLLARY MISTAKE IS USING A HAMMER & CHISEL, OR PLIERS TO MAKE THE CRIMP. USE A CRIMPING TOOL, PLEASE. In the photo, note that the barrel is crushed almost directly in the middle. Using moderate force, pull on the terminal; it should feel securely attached and should not slide off. If it does, the crimp is inadequate, and you’ll need to repeat the process.

Crimping the terminal

Slide the shrink wrap over the terminal, and heat it with a heat gun. (A match or propane torch also works, but don’t let the flame touch the material!) Within seconds, the shrink wrap reduces to less than half its original diameter, and the final repair looks very professional. You can use electric tape here also. The point of the shrink wrap or tape is to insulate your repair. THE FOURTH MOST COMMON MISTAKE IS USING TAPE TO CONNECT THE TERMINAL TO THE WIRE. IT’S THE MECHANICAL CRUSH OF THE BARREL ON THE WIRE WHICH MAKES THE CONNECTION.

Note that crush is in center of barrel


Heat gun on shrink wrap

I’m not kidding about these common mistakes. I’ve seen everything from copper wire twisted around a crimp terminal to Scotch tape used as an attempt to hold the wire and terminal together. Installing crimp terminals takes some practice; buy some wire and a terminal assortment, and practice before you need to make a repair to your car. I’ve also used solderless terminals to make up my own test wires, whether it’s to run temporary grounds, or run 12V from the battery to the rear of the car. These test wires may have alligator clips or spade terminals or some other combination; I have several, and they come in handy!


All photographs copyright © 2023 Richard A. Reina. Photos may not be copied or reproduced without express written permission.