How to Splice Automotive Wires
Updated: Apr. 20, 2022
Use a professional tool and moisture sealant for first-class results
Use a professional crimper and electrical moisture sealant to make quick, solid connections in auto wiring.
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Splice automotive wires in seconds
Photo 1: Crimp the connector
Strip the insulation so only the bare wire is inside the connector. Then make a single 5/16-in. crimp on each side of the butt connector.
Photo 2: Cut the moisture sealant
Cut a section of moisture sealant to cover the entire connector and a 1/2-in. overlap on each end.
Photo 3: Seal the splice
Then double it over and squeeze it together with your fingertips.
Crimp-on wire connectors work well if they’re crimped properly (a 5/16-in.-wide crimp) and sealed (usually with heat-shrinkable tubing). But most cheap crimping tools only make a 1/8-in. crimp, so you’d have to make four of them for a simple butt connection.
Invest about $25 in a professional crimping tool. Then buy a roll of electrical moisture sealant (3M No. 06147; about $20 from amazon.com). Then just follow the steps in Photos 1, 2 and 3. See how to fix an electrical short circuit, too.
Required Tools for this Project
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Required Materials for this Project
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.
Originally Published: November 26, 2018