Useful Hints For Using Your Vehicle’s Factory Wiring

Adding an amplifier to a factory stereo usually necessitates a lot of extra speaker wiring, both from the stereo to the amplifier and from the amplifier to the speakers.

This may seem to be an unsolvable nightmare.

We do, however, have a means to make things a bit simpler.

Note: This article describes how to connect an amplifier to a factory audio system that lacks a factory amplifier.

Soon, a Crutchfield article will be published regarding attaching an amp to a factory-amplified system.

Instead of using one of the 9-wire cables listed below, you’ll need a set of RCA cables if you have an aftermarket stereo.

For further information, see our article on installing an amp to an aftermarket radio.

To The Rescue, A Multi-Conductor Wire

Typically, a 4-channel amplifier with speaker-level inputs will be installed.

The easiest approach to connect it to a factory system is to feed the amp’s input signal via the stereo’s speaker outputs.

Then, using the original wiring, connect the amp’s outputs to the stereo’s harness and then to the speakers.

“All-in-one” Crutchfield 9-wire speaker cable simplifies this by combining the wiring for four speakers as well as an amp turn-on lead into one cable.

Connect your new amplifier to the dash using two of these cords.

One is for the amp’s input, while the other is for the amp’s output.

These wires will link your amp to the factory system through a “T-harness.”

To Access The OEM Wiring, Remove The Radio.

All of the speaker wiring are accessible from under the factory radio.

The wire harness for the radio supplies electricity and routes the output to the speakers.

You’ll need to figure out which speaker is connected to which cable.

Negative leads are generally solid-colored wires with a second-color stripe, while positive leads are usually solid-colored wires with a second-color stripe.

Please keep in mind that the wire colors vary greatly from one vehicle to the next.

Our Tech Support staff can check up the wire colors for you if you buy your new gear from Crutchfield.

Before you start tearing up your dash, give us a call so you know what to anticipate.

Related: 10 Best RV Stereos of 2024

Join The Wires Together.

Cut each of the eight speaker cables after you’ve located them.

Connect the radio plug’s end to a new wire that goes to the amp’s input.

Connect the speaker wire to the appropriate wire coming from the amp’s output.

This means you’ll need two 9-wire cables, one for the amp’s input and the other for the amp’s output.

The 9-conductor wires for amplifier in/out go to the right, the radio plugs in at the top, and the car wiring goes to the left.

(It only took me about 40 minutes to wire this harness for illustration, even with my poor vision and shaky hands.)

Don’t Bother With The Turn-On Lead.

“Signal-sensing turn-on” is a feature found on amplifiers with speaker-level inputs.

When an input signal is present, the amp switches on.

This signifies that neither cable’s ninth wire (the blue wire) is used for this arrangement.

Something You Could Need

The radio may shut down if you cut the stock speaker cabling since it can’t identify any speakers attached to it.

In order for the radio to work effectively, you must install a load producing device on each output channel.

Related: How Do I Add Bluetooth To My Car?

Installation Advice From A Pro

Mark both ends of one of the 9-wire wires with electrical tape before running them through your automobile.

Once the wires are in place, you’ll be able to tell which ones are for amp inputs and which are for amp outputs.

Here Are Some Tools To Assist You.

Because each pair of speaker wires is color marked, we like the Crutchfield 9-wire cable pictured above.

If you like, we also have a variety of highly conductive, pure copper speaker wire available by the foot.

Posi-Products Car Stereo Connectors in a multi-pack might come in helpful here.

You don’t need to solder or crimp anything to create all of the speaker connections.

This task will be covered by one package, plus you’ll get a few extras.

PAC Audio has a few vehicle-specific T-harnesses that will allow you to add an amplifier to a limited number of cars with factory stereos that aren’t amplified.

For these installs, you’ll also need 9-wire cable to connect your aftermarket amp’s inputs and outputs to the system.

Larger Cables Are Required For High-Power Amplifiers.

It may be preferable to install new 14- or 16-gauge speaker wires straight from the amplifier to each speaker for amps with more than 75 watts RMS of output per channel.

Factory speaker wires are very thin and have a great resistance to electricity.

When greater wattages attempt to get through, they might cause substantial power loss.

However, amplifiers with a power rating of 75 watts or less are unaffected.

Running their output via OEM wiring is still a viable and practical option.

Related: What Is Stereo Audio?

Converters With A Line Output

A line output converter is another typical method for connecting an amplifier to a factory radio.

It connects to the OEM radio’s speaker wires and transforms the signal from speaker level to preamp level.

This allows you to send the signal to your amplifier using RCA cords.

The capacity to sum and regulate signals of a multi-channel industrial system is one of the benefits of a line output converter.

If you’re updating a complicated system, a line output converter can be the best choice.

The speaker cable solution we’ve described here is a less-expensive, simpler one that will work for the majority of folks.

More information about line output converters may be found here.

Please Let Us Know What You Need.

The emphasis of this paper was on a method for simplifying speaker hookups.

Check out our Amplifier Installation Guide for further information on other areas of amplifier installation, such as power and ground wiring.

Contact our consultants through chat or phone if you have any queries about attaching a new amplifier to your speakers.

They’ll spend time answering your questions and explaining the technicalities before setting you up with everything you need.

Related: How To Find Ignition Wire For Stereo?

How To Connect An Amplifier To A Factory Stereo Videos Suggestions From Youtube

How to install an amplifier to factory radio – JPtheinstallguy
How To INSTALL a Line Output Converter w/ Stock Radio & Speakers 4 Aftermarket SUB AMP Installation – EXOcontralto
How to: Add Aftermarket Subwoofer and Amp to Factory Stereo. – JCT FIX IT

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Written by Bob Matsuoka
Bob Matsuoka is a blogger and founder of RVing Beginner blog. He has been blogging for over five years, writing about his own family’s RV adventures, tips for people who are interested in buying an RV or taking their family on an adventure by RV.