Salvaging Bits from Wiring Looms

This article was first published in 2004.

Head off to a wrecker and you’re sure to see some wiring looms sitting around. Often they’ve been cut to get them out of the car and as a result, the wrecker sees them as worth nearly nothing. For example, I’ve bought three large looms in the last few months at AUD$10 each.

So what good are they then? Well, you can get a whole heap of good parts from a wiring loom – let’s take a look.

Firewall Grommets

If you’ve ever installed programmable management, an interceptor – or even just wanted to feed a whole heap of new wires through the firewall – you’re sure to have come up against the problem of sourcing an appropriate grommet. Off the shelf hardware store items aren’t usually suitable because (a) they’re not big enough and (b) they don’t have the ‘tail’ that makes proper firewall grommets weatherproof. But in a typical wiring loom you’re sure to find one or two that are suitable.

There are those that look like this...

...or larger oval-shaped ones like this.

Some looms even have firewall grommets that are backed by a metal plate that bolts to the firewall.

Sensor Plugs

Want to install an extra injector? Or swap an airflow meter? Often you’ll find that sourcing the plug is the hardest part of the modification. But if you pick a loom that’s from your make and model of car (or often any model from your car’s manufacturer that was produced at about the same time) you’ll find the right plugs in abundance.

This loom has ECU plugs....

...and an airflow meter plug.

You’ll also find two-pin plugs...

...and other two-pin plugs to suit injectors. In short, there’s plenty of plugs of a myriad different designs!

Relays

Even if most of the components have been unplugged, many harnesses have relays still attached. Because they come with a dedicated plug and a length of cable, they’re easy to add to your car while still looking factory and professional.

This relay comes with wiring, plug and bracket while...

...this design has a rubber shroud that can easily be mounted on a custom made vertical bracket (it slides in where the arrow is).

And if you want a full relay board, try this out for size! Often the individual relays and their dedicated holders can be removed – handy if you don’t need a massive relay upgrade to the wring.

Dedicated fuse boxes can be found in nearly all discarded wiring looms. Here’s how a fusebox salvaged from a loom was used in the installation of a high-powered intercooler fan. The fusebox contains two high-current fusible links.

This fusebox is perfect for a general purpose upgrade – it has some fusible links, fuses and a relay.

Fasteners

If you want to make new wiring look factory, you’ll need to use factory-style fasteners to hold it in place. (This is so much nicer than just cable-tying it to existing wiring!)

A variety of fasteners is used on looms – here the top one is designed to clip into a drilled hole while the bottom attaches over the exposed thread of a bolt. In both cases the loom is easily attached to the fastener with normal electrical tape.

This loom fastener comes with its own plated bracket.

This fastener is designed for a bulky loom and clips into a panel hole. It is easily undone from the existing loom.

Wire

And don’t forget that when you buy an old wiring harness you’re also acquiring a huge amount of useful insulated wire!

As can be seen here, there’s a wide variety of gauges, suitable from handling heavy battery loads right through to wiring-in sensors.

Sometimes heavy duty lugs will already be crimped to the ends of the thickest cables – very useful as getting a good crimp or solder connection can be difficult on heavy-duty cables.

Bits and Pieces

And you’ll also find convoluted tube in a variety of sizes, multi-pin plugs and sockets (used to connect parts of the loom), in-harness fusible links, battery terminals – and a whole lot more.

Conclusion

If you can pick up a wiring loom for a few bucks – especially if it’s your car’s make or model – do it. Put it to one side then when you need a fusebox, or a relay socket, or even just a length of small diameter convoluted tubing or some fasteners, dig it out. The on-car wiring job will look and work so much better.