Broken Battery Ground Wire: 3rd Gen Toyota 4Runner

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Broken Ground Wire Between Battery & Body

What exactly is this cable that is attached to the body and what is it supposed to be attached to? This short cable that is broken off in the photo below is a battery ground cable. This cable should be connected between the negative terminal of the car battery and the body of the vehicle.

Over time, if the battery is not securely tied down, the wire strands of the battery ground cable can fatigue and break due to constant movement. Rust and corrosion will accelerate this process. Because this ground cable is so short, there is little room for it to move around and so there is a higher chance for this wire to break off.

Even if this battery ground cable breaks, you might not see any visible issues. Keep in mind that there are still other grounding points on the vehicle. However, this ground cable is one of the major paths for electrical current to return to the negative terminal of the battery. This can potentially be a safety issue and you might see some voltage issues as well.

Tools & Materials

New Ground Wire (Replacement) or Ring Connector (Repair)

You have two options for repairing this connection:

1. Replace the broken ground wire with a brand new battery cable. This cable is a much larger gauge than the existing wire, but is a common size you’ll find if you’re looking for a battery cable.
   Black Single 12 inch or 1 Foot Negative 2 AWG Gauge Battery Cable
   
2. Repair the connection assuming you have enough length of the cable to attach to the negative terminal of the battery (this is what I went with.)
   InstallGear 4 Gauge AWG Tinned Pure Copper Ring Connectors with Heat Shrink – 10-Pack

Electrical Tape

If you replace the ground wire, you won’t need any electrical tape. If you make a repair, it’s optional to wrap it with electrical tape. I’ve always wrapped any crimped connections as I’ve found it to help with distributing some of the load when flexing, so that any movement is less likely to work the connection loose again.
3M Scotch Vinyl Electrical Tape Super 88, Premium Grade All-Weather, 3/4 in x 44 ft, 8.5-mil thick, Black, 1 roll

Crimping Tool

If you’re making a repair using a ring connector, you’ll need a crimping tool for a larger sized gauge wire such as this crimping tool. You just hammer it down to crimp. Another option is to use a large set of pliers if it provides you with enough force to crimp the connection.
TEMCo Hammer Lug Crimper Tool 5 Year Warranty

Fixing the Broken Battery Ground Wire

I simply cut off the frayed end of the battery ground wire, stripped off about 1/2″ of the jacket insulation, and then crimped on a new ring connector.

I then wrapped the whole connection along with the wires with two layers of electrical tape.

I then connected the battery ground ring through the negative terminal bolt connection and tightened everything down again. It’s a simple repair, but it helps me to be rest assured that the body of the 4Runner is re-attached to the negative terminal of the battery.