What Is a Factory Amp Bypass? – Universal Amplifier Bypass Guide

What Is a Factory Amp Bypass 2

Its pretty frequent that we get customers that have audio issues due to factory amplifier or speaker mishaps that require an amp bypass.

Sometimes its pretty cheap, other times the owner has to save up for a bit to cover the cost. Its all dependent on the way the manufacturer built the audio system.

Its important to understand that not all audio issues can be solved with a factory amplifier bypass. Heck, not all cars come with a build in factory amplifier to bypass in the first place.

Before you get started we recommend that you have a wiring diagram handy. There could be very important wires that are connected to your amplifier. With a wire diagram you can spot these before you start to cut those wires. If you see wires that are important or that you do not immediately understand such as can bus wires you should consult your local car audio shop. We are not responsible for any issues that come about after using this guide.

Why Would You Need To Bypass Your Amplifier?

There are a few reasons you would need to bypass a factory amplifier. The most common have to do with the factory amplifier not producing enough quality, going bad or our favorite; a speaker is blown and is next to impossible to find.

Here’s a quick list for your reference of places to check when you have audio issues in a vehicle with a factory amplifier. This will also let you know if a factory amp bypass might be necessary:

IssuePlaces To CheckAmp Bypass Needed?
Speaker BlownSpeaker, Wiring at amp & SpeakerLikely if speaker or wiring is okay
No audio at all (or very low)Check to see if amplifier is turning onVery Likely
More distortion than usual over timeCheck Ground at amp and radioLikely if radio is not the cause
Looking for better audio qualityDoes not require a checkVery Likely
Adding a subwooferDoes not require a checkNot likely (Use High Low Converter)

what is a factory amp bypass?

Simply put, a factory amplifier bypass is essentially removing your factory amplifier or its functionality from your vehicle.

What your doing is trying to send audio from your radio strait to your speakers without the amplification process taking place. Remember, the amplifier lives between your stereo and your speakers.

There are things to consider before removing your amplifier such as:

  • Do you have the proper tools?
  • What reason you have to remove it
  • Are you installing another amp in its place?
  • Do you have the proper wire diagram?
  • Will you be keeping any audio products that might need the amp?

For A List Of the parts youll need for this job take a look at our: Amplifier Bypass, Troubleshoot and Installation Page.

What tools do you need for an amp bypass?

What You’ll NeedWhy Do you Need it?
Digital multi meterFor testing Continuity and Power
Wire CuttersFor cutting wires
Wire StrippersFor stripping wires
Crimpers (if not soldering)For crimping the but connectors
Tone GeneratorFor testing to see if your speakers are hooked up properly
Electrical tapeTo clean up wires and cover soldering points
Zip TiesTo hold wires up in a safe place
But Connectors If not using a soldering ironto connect wires if not using solder
9 wire (Speed Wire)To run wires if input and outputs are far from one another

Where Do I Find The Parts I Need?

We actually took some time out and went through our tools and thought about the tools we use to complete amplifier bypasses. We came up with a pretty long list and realized pretty quickly that we need to inform you guys why they are important and when to use them.

In comes our in depth AMPLIFIER BYPASS, INSTALLATION and TROUBLESHOOT RESOURCE PAGE. We explained when each tool should be used and where to purchase them when you need them!

How To Perform A Factory Amp Bypass

Remove your Radio

Remove your radio so that you can examine your wiring for your 4th step. This also helps keep the factory radio safe from electrical system safe. This is a good idea if you intend on installing an aftermarket stereo as well.

Locating the factory amplifier

Contact your local dealership or do a quick google search to find your factory amplifier.

In shops we have a lot of resources that we use in order to locate wires and different things in your vehicle, we understand you wont have these tools. Google has came in clutch for me more times than I can count.

After locating your amplifier take a look at the area its located in and plan your wiring. Also, if you plan on installing a new amplifier in place of your factory one this would be a good time to plan a mounting location!

Checking Harness

Once you’ve located your wiring plugs on your amplifier, inspect them for any damage.

Your next mission should you choose to except it is to identify your power and ground wires. This will require you to set your digital multi-meter to the Voltage direct current setting.

Once you’ve done that start to check for matching wire colors, if you find them this is a good indication that you found speaker wires! If not, that’s okay, we’ll find them.

What Is a Factory Amp Bypass 2

Locating Input and Output wires

Your input wires are the audio wires that are coming from the back of your stereo that send sound to your amplifier.

Your output wires are the wires coming from your amp that are sending audio to your speakers.

  • The first thing to do is to identify your power wires. Turn your digital multi meter to the “Voltage direct current setting.
  • Put your negative probe to a solid “ground” on the vehicle such as an un painted bolt or any unpainted metal surface. (try to stay away from small welded metal panels).
  • Use your read probe to probe the thicker wires on the harness that has them. When your meter reads 12v or more you have found your power wire. (write the color down)
  • Now put keep that probe on the power wire and use the black probe to meter the other thicker wires on that harness. When your meter reads 12v or more you’ve found the factory ground wire. (write the color down)

After you have identified your power wires and wrote them down its time to find your input and output wires.

  • Start by locating your radio harness in the dash cavity where the radio you removed was. The harnesses you unplugged from your stereo could have all of the wires youll need.
  • Try to find wires at the stereo harness that match the wires at the amplifier. If you find a matching set if wires make sure to meter them with your multi meter set to “continuity”.
  • If you don’t see any matching wires that’s okay! You’ll just need to put in a bit more work.

You’ll need to start from the basics if you have not found a matching pair. To do this youll need to put one of your probes on one of the smaller gauge wires on the radio harness.

While the probe is wedged into the harness that was connected to the radio you can start to probing the wires that were attached to the amp one by one.

  • Use the other probe to probe each wire on the amplifier harness with it unplugged. With the multi meter
  • Go wire to wire on your amplifier harness with your meter set to “continuity”. When you’ve found a match youll here a “beep” tone.
  • When you hear that tone make sure to write down the color of that harness plug and label it “INPUT HARNESS“. You found it!

Now that you’ve found your input harness its time to move on to the the other plug.

If your amplifier only had one plug then your both your input and output wires will be on this harness, If you have multiple plugs (more than one) you will need to move to the other harness(s) for the next step.

Verifying speaker wires at the speaker

This step will require you verify the speaker wires (output wires) at your amplifier harness. This can be done 2 different ways.

The first way – Remove all speakers and write down the speaker wire colors for each speaker and the location of the wires.

With the speakers removed you can run a continuity check with your meter from your amplifier harness to confirm. This will find the wires for you if the wires do not match up as well.

Once you have confirmed continuity of all speakers wires at the amplifier plug your all set to start testing for phase.

Now re-install the speakers – You’ll need to install the speakers back into their location. There are 2 wires for each speaker, the problem is we don’t know which of each is the negative or the positive.

Now you can install your new speakers!

Verifying Phase is correct

For this next step youll need a tone generator, they aren’t expensive and can be found on amazon pretty cheap. This tone generator will allow you to find out which speaker wire is negative and which is positive, this will be done for each pair around the vehicle.

With all your speakers connected go to the plug that you previously determined to be the output plug in the previous section and use your tone generator to send a pulse to each speaker. Before doing this you should:

  • Identify your output wires that you found in the previous section.
  • strip the wire jacket back about a half an inch on those wires.
  • Hook your tone generator positive probe to one wire and the negative probe to the other.
  • press the tone generator button that sends a pop sound to the speaker.
  • While its popping your tone generator should show a blinking light
  • If the light that corresponds to “IN PHASE” write down which wire from the amp harness that you have connected to the negative probe and the positive probe.
  • Complete this for all speakers.

Making connections on harness

Now that you’ve found the correct input and output wires and you’ve written them down you can begin to make the connections at the amplifier location.

  • Start by cutting the wires at the plug(s) one by one. Leave at least 4 inches of wire on the plug. Make sure to cap off or tape the ends of the power and ground wires at the plug to avoid any shorting to your radio.
  • Strip about a half an inch from each wire to make a connection.
  • If you are using but connectors start to make your connections and crimp wires.
  • If you are using solder then twist corresponding wires together.
  • Pull the twisted pair a bit to verify proper connection and then solder them.

Now Install your stereo and test your audio, If is sounds good then you did it!