After all of the hours you've spent researching, planning, and purchasing your parts and equipment for your brand new aftermarket radio system you've been so eager to use, it is now time for the installation part of your build! We here at Stinger get many questions about wiring you're aftermarket harness to your aftermarket radios harness! We've created this article to assist with those common questions and weird situations to hopefully make your install a breeze like it should be!

 

We will be discussing the methods of installation according to the Mobile Electrionics Certified Professional (MECP) recommended practices. Learn more about the importance of MECP here: https://mecp.com/vehicle-owners/www.MECP.com

 

A lot of aftermarket equipment uses a set standard of colors for most wire functions. You may find that some radios will not have matching wire colors between harnesses. This is why we focus on the actual named function of the wire listed in manuals versus wire color at times.

 

This article does not include Steering Wheel Control Connections.

As long as the functions match between your wires on your aftermarket wiring harness to your aftermarket radio's harness, you should rockin' in no time! First, lets start by understanding how to identify and properly connect wires together in a vehicle environment.

 

These guides do not apply to our Plug-&-Play SR or SRK HEIGH10 integrated kits as these are pre-wired for you.

 

Identifying Wire Colors

Typically we see a few various wire colors on the wire itself. Some are solid, some are striped, and in some vehicles the wires are striped with dots added for an additional means of idenification.

Solid colored wires are only one color across the entire wires insulation. Striped wires will have a primary color that is more prominent on the wire than the striped color. We call the striped color the "Tracer" on the wire.

Solid colors are spoken with just a single color such as "Red" or "White" or "Purple"

Striped (Traced) wires are spoken with the primary color listed first followed by the color of the tracer such as "Red/Black" or "Purple/White" or "White/Orange" and so on.

Here are some examples to look for when wiring harnesses together whether in an aftermarket application or even OEM integration applications. Use this as an aid to this guide and any future installations you might be doing!

 

Solid Wires	Striped Color (Traced Wires)

 

Properly Making Connections

Before getting into wiring, we should discuss how we are planning to make these connections wire for wire! There are good ways and bad ways to make these connections. For your safety, the vehicles' safety, and for the sake of doing the job properly, we will discuss the proper ways to make your wire for wire connections that will not become compromised due to vibrations experienced in vehicles as you drive.

No, wire-nuts are not approved for usage in automobile installations.

 

Soldering

MECP Recommends that Soldering be your preferred method of connecting wires to each other in tandem with using Heat Shrinkable Tubing to protect your soldered connections.

 

An example of soldering connections is pictured below using a set of "Helping Hands" to hold the two wires in a manner that allows us to easily twist the wires together and then solder them together.

It is also recommended to use Flux to aid in the solder flowing into your twisted wires.

You may also use Dielectric Grease before adding your heat shrink to aid in corrosion protection.

Helping Hands holding the wire that is ready to be twisted.	Wires twisted together, ready to have flux applied and soldered.
Twisted wires now have flux on them	Wires soldered together using a soldering iron.

Once you have finished soldering the wires, you can use your heat shrink to protect the bare-soldered connection!
 

Butt-Connectors

The Second method of wire for wire connections is to use Butt-Connectors or Crimp Caps!

Essentially, a butt connector uses a plastic insulated tube with a metal crimp section that when using the proper tools allow the two wires to be crimped together inside of the butt-conector. It should be noted that there are many types of butt-connectors out there from poor quality to marine-rated type quality.

There is no soldering involved however there are many newer types of butt-connectors that have a type of solder that once heated with a heat gun or similar, it will melt inside of the tube and solder the wires together. A lot of high-end butt connectors will also have Heat Shrink tubing built into the butt-connector that will protect the bare connections from corrosion. It is also recommended to use Dielectric-Grease on these connections when using in outdoor/marine applications.

 

Wires are first stripped to bare copper using a wire stripper, inserted into each end of the butt-connector, and then crimmped using the appropriate tool.

 

Here are some photos of the various types of butt-connectors 

Standard Butt-Connectors (Crimpable)	Heat Shrink Butt-Connector (Crimpable)	Solder/Heat Shrink Butt-Connector (Non Crimpable)

Your finished crimped connections should look similar to these. You have completed a proper crimp when the wire no longer is able to be removed from the butt-connector.

 

Crimp Caps

Crimp Caps are essentially the same as a butt-connector but the wires you are joining are inserted and crimped from only one end instead of two how you would on a butt-connector.

All of the same properties for crimp caps are the same for butt connectors, the connections are simply made from one opening. It is not recommended to use a solder-type of crimp cap in this situation.

 

Wires are first stripped to bare copper using a wire stripper, then twisted together in a sprial, then inserted into the crimp cap and then crimmped using the appropriate tool.

Common Crimp Cap	Crimp Cap with wires inserted and crimped

 

Power Connections

The most important connections are the ones that power the radios 12V Constant circuit, the Key-Switched Accessory wire, and the Ground that completes the circuit for the aftermarket radios power.

They are typically your Solid Yellow, Solid Red, and Solid Black wires found on both the radio and the modules wiring harnesses. They are typically labeled in the manual's as 12V+, ACC, and GND.

 

The Solid Yellow wire denotes 12V+ which is simply a constant source of 12V power to the radio so it saves the time/date, presets, and in some cases, user settings and Bluetooth pairing profiles to the radio.

 

The Solid Red wire denotes Accessory which is a wire that activates when the vehicle key is turned to ACC/Accessory. This is not the same as the Ignition/IGN/ON wire. The reason we use the ACC position is to prevent unnecessary drain on the vehicle from the other systems in the vehicle we arent using, draining the battery prematurely.

 

The Solid Black wire denotes Chassis Ground which is the return wire voltage takes in an automotive circuit. All 12V accessories installed in a vehicle require this connection to complete the path from the positive battery terminal to the negative battery terminal. This connection is also crucial as an improperly grounded component can cause a multitude of issue from power loss to extremely annoying noise in the audio system.

 

Your wires from a vehicle harness to the aftermarket radio should look similar to this once you have connected the power connections from one harness to the other.

Note, in Radio Pro modules and kits, there will be a harness attached to the module you would wire your aftermarket radio to. See your Radio Pro's manual for more information.

 

If after you have installed your aftermarket radio and the unit does not power on when the key is in the Accessory position, you will want to use a multimeter set to DC Voltage ⎓ and check that the circuit has 12v on the yellow constant 12V wire at all times (even when the key is off) and the red wire should have 12V only when the key is turned to the ACC and RUN position.

You can check this by taking your black multimeter probe and touching the bare copper from the black Ground wire and your multimeter's red probe touching either the yellow or red wires' bare copper. You should get between 12-14V depending on battery condition and if the vehicle is running or not. If you have 0V or less than 12V on either wire, you will need to investigate why the battery is low or check connections for a poor connection. In most cases, the issue could be the fuse in the vehicle for the radio circuit.

Note: No other wires typically inhibit the radio from powering on and off. It is the sole function of these three wires to turn on and off the aftermarket radio. If your radio does not turn on, you must start your troubleshooting with these three wires.

 

Audio Connections

Now that we have sorted out how the radio is powered and turns on, we have to sort out the audio signal from the aftermarket radio and its path to the OEM amplifier, aftermarket amplifier, or simply just to the speakers.

There are a few different ways audio transmission can happen from an aftermarket radio to your speakers, or amps depending on the situation. We are going to focus on only two. Speaker Level signal (High Level) and RCA level signal (Low Level). The main differences that you see are one uses an RCA jack and the other is simply wire to wire as we have discussed above.

 

Speaker (High) Level Signal

Typically, if you are only installing an aftermarket radio, you will be using the colored set of speaker wires denoted in your products manual. By standard, these colors are typically set across most manufacturers but be warned your color may vary. Always verify connections by function in both the harness manual and the aftermarket radio manual when in doubt. Audio that is transferred at a voltage suitable to play a car audio speaker is considered "High Level Signal".

Not all installations are the same. Please ensure you read the manual for your wiring harness before installing in case of special instructions, procedures, or wire colors.

The standardized colors and functions for speaker level audio signal are typically as followed:

White	Front Left Speaker Positive +
White/Black	Front Left Speaker Negative -
Grey	Front Right Speaker Positive +
Grey/Black	Front Right Speaker Negative -
Green	Rear Left Speaker Positive +
Green/Black	Rear Left Speaker Negative -
Purple	Rear Right Speaker Positive +
Purple/Black	Rear Right Speaker Negative -

Typically the above wires will be the same on both the wiring harness and the aftermarket radio harness.
If these are not the same color on either side, reference the manuals for the products you have to verify function and color on each side.

In a normal situation, your wiring should look like the photo below once you have completed your speaker wiring to the aftermarket radio harness. (We soldered these connections to show the different ways. You do not have to solder these connections if you wish to use crimp caps or butt-connectors) 

Note, in Radio Pro modules and kits, there will be a harness attached to the module you would wire your aftermarket radio to. See your Radio Pro's manual for more information.

 

If your radio powers on and functions but you hear no audio, checking these connections is a great first step to make sure they arent touching bare metal, ground, or 12V power. Some aftermarket radios have protection circuits in place to prevent damage to the unit. It is also a good idea to test the speaker wires from the aftermarket radio unit to make sure you indeed are producing audio from it using a new speaker or a spare one you may have lying around. If you are still not getting audio, we will discuss OEM Amplifiers and the remote circuit in the Remote Power Section below.

 

RCA (Low) Level Signal

In certain situations such as vehicles where we want to retain the OEM Amplified audio system and its built in features, we will need to use a Low Level signal suitable for the OEM amplifier to use. In cases like this, if we were to feed the OEM amplifier a High Level signal as previously discussed in the last section, it would likely cause a lot of distortion and hiss in the OEM system and even setting Volume 1 on your new radio would be extremely loud in this case.

When you run into this OR when your Radio Pro harness/module includes speaker outputs that are terminated by an RCA, your OEM amplifier will likely need a Low Level signal.

Your aftermarket radio will likely provide a set of "Front" and "Rear" RCA connection spots for use with amplifiers. The signal that comes out of these RCA's on the new aftermarket radio are the correct Low Level type that an OEM Amplifier will need to produce the same sound if not better than what the OEM Radio produced.

In the example of these connections, we are using the Alpine ILX-W670 radios Low Level RCA connections going into the RP4-GM32 module which has Colored RCA's terminated on the harness. The colors of the RCA's from the RP4 harness will translate over to the respective RCA's on the radio harness as seen below.

Note: the power connections and other wiring were not connected for the purpose of this section.

Note: BHA and XWH harnesses may also have terminated speaker leads with an RCA as shown above.

 

Remote Turn On

On the topic of retaining OEM Amplifiers, and adding aftermarket ones, we have one special wire that controls when the OEM and aftermarket amplifiers turn on.

This wire typically has many names, but universally, we call it the "Remote" wire. It is typically a Blue/White wire depending on the manufacturer of the products you are using.

This wire is typically delayed a few seconds after the radio powers on to not produce noise on the OEM or aftermarket amplifiers due to everything powering on at the same time.

Not all installations are the same. Please ensure you read the manual for your wiring harness before installing in case of special instructions, procedures, or wire colors.

In Radio Pro Harnesses and other PAC Harnesses, we are looking for a 12V signal output from the aftermarket radio's Blue/White wire. When the Radio Pro module receives 12V on its Blue/White, the module will turn on the OEM amplifier.

 

In the example below, we have the Alpine ILX-W670 again to show how their remote wire is connected. The Alpine's Remote wire is labeled "REMO" in this example and we have connected the Blue/White from the RP4-GM32 harness. This connection allows the radio to decide when the Radio Pro module turns on or off the OEM Amplifier and/or the aftermarket amplifiers.

In cases where you are adding an aftermarket amplifier and keeping usage of the OEM amplifier, you can connect the Blue/White wires together at the same connection point.

 

If you are not getting audio after completing your installation and you have verified audio is being produced by the aftermarket radio, you will want to check with your multimeter for 12V on the Blue/White wire while everything is connected and powered on. If you do not have 12V on the Blue/White wires and you have an OEM Amplified or Aftermarket Amplified system, this could be your issue.

 

 

Power Antenna

The power antenna wire is exactly for what its named. Vehicles that have an OEM motorized or powered/amplified OEM AM/FM antenna need their own trigger to tell the antenna when to power on or extend depending on the vehicle. Typically this wire is Solid Blue and labeled "Power ANT" but can be named differently depending on the manufacturer of the product you are using.

 

This wire would be connected to your vehicle only if you have a powered antenna. Sometimes the wire is directly connected to the blue wire you may have coming from your Antenna-Adapter and sometimes the wire connects to your radio replacement harness/Radio Pro kit.

 

In the image below, we have an aftermarket radio harness on the left with a solid Blue wire labeled "P.ANT".

Some vehicles will not use this wire at all.

 

Reverse, Parking Brake, Vehicle Speed (VSS), and Illumination

Getting down to the last wires here! We are left with a few wires. Among those wires are likely your Parking Brake, Reverse, Vehicle Speed Sense, and Illumination. We typically call these "Navigation Outputs" or "Nav Outputs" for short. This does not mean your vehicle or aftermarket radio has to have navigation built in for these to work. The PAC Harness takes care of it all for you!

Some installations will use these wires and some installations may not need them or simply arent used by your aftermarket radio depending on the features offered in the unit.

Before we discuss the functions, we will take a look at the two different color sets that these wires can be on a PAC module. Its very easy to understand once you are aware of what the wire functions are and you can simply pair the wire with the matching wire on the aftermarket radio harness.

 

Nav Output Colors

We have two modules shown below. The RP5-GM31 and the RP4-GM32. All other wires on these harnesses (Power, Speaker, REM/ANT) are the exact same. The only wires that are different are some of the Nav Output wires. These modules use the two different variants of Nav Output colors. In the table below, we have listed the color to function for each harness type. Use this to follow along further in your wiring so we do not make incorrect connections. We have also put colored dots to help visually.

TYPE 1	TYPE 2
Red/White - Parking Brake Teal or Green - Reverse Purple/White - Vehicle Speed Sense Orange/White - Illumination	Teal or Green - Parking Brake Purple/White - Reverse Pink - Vehicle Speed Sense Orange/White - Illumination

As you can see, the easiest way to tell the color set of Nav Output wires you have is to look for a Pink or Red/White wire. These colors are also listed in the manual for your PAC Harness. You should always make sure you are connecting your wires by function and not just color. The above differences are a clear reason as to why.

 

Parking Brake

The Parking Brake wire is used by your aftermarket radio to tell the radio when you are stopped fully and the Parking Brake is set. This would indicate the vehicle is completely motionless, in Park/Neutral and the Parking Brake set. This wire is NOT triggered when your foot is on the brake. Failure to connect these wires from the PAC Harness to your module will render some features and menus inoperable. Videos will not show on display enabled radios, certain configuration menus will become inaccessible and certain setup processes cannot be complete, such as Android Auto, if the Parking Brake wire is not connected.

PAC Modules and standard harnesses that offer this wire control the parking brake input wire found on your aftermarket radio.

Make sure to check your aftermarket radios installation manual to match the wires by function and not just color.

 

Reverse

The Reverse wire works exactly as it states. It is a 12V trigger that is activated by the module when the vehicle is placed into the reverse gear. This wire when connected to the aftermarket radio wire will make the radio show the OEM or Aftermarket reverse camera you may have. You should also have your camera RCA connected to your aftermarket radios "Reverse Camera" input RCA.

Make sure to check your aftermarket radios installation manual to match the wires by function and not just by color.

 

Vehicle Speed Sense (VSS)

Vehicle Speed Sense is the wire directly linked to your vehicles speedometer. The PAC module will take this information that is transmitted from the transmission and allow radios that offer a VSS input to use this data to more accurately run built in GPS system functions. Most radios that offer any sort of Built-In GPS will have a connection for the VSS wire.

Make sure to check your aftermarket radios installation manual to match the wires by function and not just color.

 

Other Connections

In this article we will only go over wiring connections that allow the aftermarket radio to function properly. This article does not include steering wheel control connections. Please visit this page for assistance installing and understanding steering wheel controls. If you would like assistance outside of the manuals guidance regarding any other wiring you are unsure of, please contact Technical Support here, or reach out to our Facebook group.