No Door Speaker Output or Poor Radio Reception After Installing Aftermarket Head Unit

[FR-S2GT86]

Hello everyone.

I wanted to address some issues brought up in some recent posts concerning the installation of aftermarket head units into our vehicles when this is the ONLY upgrade that you are performing to the sound system. If you are installing aftermarket amplification IN ADDITION TO a new head unit, this will most likely NOT apply to you. However, it still may if you have lost AM/FM reception, and/or your amplifier(s) won’t power up if you are re-using the OEM amplifier turn-on wire running from the dash opening to the trunk. If any of these scenarios is the case for you, please continue to read on.

What this write-up DOES NOT cover, is any integration of back-up cameras, steering wheel controls, microphones, USB connectors, etc. The main topic here is making sure your amplifiers and antenna power up properly when you have completed the installation of your new AFTERMARKET head unit.

Please note that this write-up is based on the reader also purchasing and using an aftermarket wire harness and an antenna adapter, both of which are available from companies such as Scosche or Metra, in order to ease the installation of their new head unit. IT’S ALWAYS BEST NOT TO CUT FACTORY WIRING, and I cannot express this any better. This is also written with the assumption that the reader has no experience with car stereo installation. So to all the readers here who ARE experienced with aftermarket car audio installation, please keep this in mind as you follow along.

I will also be referring to five separate and distinct harnesses and antenna cables in this write-up. They are as described here:

1) "Harness A" is the harness and plug supplied along with your new aftermarket head unit, and which plugs directly into the back of it. Usually, (but not always) there is only one plug/harness assembly included with the head unit which will consist of all four speakers, and all of the power and ground wires. This harness will be brand and model specific to the aftermarket head unit and is not going to be interchangeable between other stereo brands. They MAY be interchangeable between SOME MODELS within the SAME BRAND, but not always. If you don't have this harness, you won't be able to use your new head unit in your FR-S, BRZ or 86 or ANY OTHER vehicle for that matter. You won't even be able to bench test your new deck without it. Diagram #1 is an example of “Harness A”.



2) "Harness B" is the ADAPTER harness and plug that will marry "Harness A" to the OEM radio harness of the car. Again, Scosche or Metra and other manufacturers supply these and are purchased separately from the aftermarket head unit according to what make/model (and oftentimes features) of the car you are installing the new head unit into. Many times there are multiple plugs and harnesses that will be provided in the package. Diagram #2 is an example of “Harness B”.



3) "Harness C" is the OEM radio harness (or multiple harnesses) and plug(s) that will plug into the back of the OEM radio that you are removing from the car. It (they) will NOT plug directly into the back of your new aftermarket head unit. Diagram #3 is an example of “Harness C”.



4) The "Antenna Adapter" is used to marry your new aftermarket head units' antenna input receptacle to the cars' OEM-style antenna plug. There are many different OEM antenna plugs found in the many different vehicle makes and models out now, but ALL aftermarket head units with a radio tuner built in will use a Motorola Din-style receptacle, which is an aftermarket industry standard. Diagram #4 is an example of the “Antenna Adapter”.



Side note: Many years ago, the Motorola Din-style plug and receptacle was ALSO the OEM industry standard on most OEM radios, with just a few exceptions that I needn't mention here.

5) The “OEM Antenna Plug” is the antenna lead and plug inside the dash opening of our cars that supplies AM and FM, and HD Radio reception to ANY radio, whether it be aftermarket or OEM. When you pull the antenna plug out from the back of the FR-S, BRZ, or 86 OEM radio antenna receptacle, you will notice that there is an additional wire that is partnered with the antenna cable. That wire is very important for proper radio reception as I will explain soon. Diagram #5 is an example of the "OEM Antenna Plug".



To summarize what I have explained about the harnesses and antenna leads so far, we have:

"Harness A" = aftermarket head unit
(see Diagram #1 above)

"Harness B" = adapter between “Harness A” and “Harness C”
(see Diagram #2 above)

"Harness C" = OEM in the vehicle (do yourself a HUGE favor and DON’T CUT this out of your dash)
(see Diagram #3 above)

"Antenna Adapter" = self explanatory
(see Diagram #4 above)

“OEM Antenna Plug” = self explanatory
(see Diagram #5 above)

With the FR-S, BRZ and 86, there are two wires that this write up is going to focus on: the factory AMPLIFIER TURN-ON lead, and the POWER ANTENNA lead.

I know what you're thinking, "Okay, we know that there is a factory amplifier in these cars mounted just behind the back seat near the spare tire that supplies an amplified speaker signal to each of the two door speakers with a low pass crossover built in and a fixed gain setting which can make integration a pain sometimes...……. but what is this power antenna that you are talking about? These cars don't have a telescoping antenna that goes up and down. What year are you living in man, 1986?"

And you would be right in pointing all of that out, along with the very appropriate and well deserved insult. However, the radio antenna in our cars are AMPLIFIED. That partner wire in the OEM antenna plug that I mentioned above within the description of the “OEM Antenna Plug” needs to have +12 volts applied to it while the AM/FM tuner source of the head unit is in use, in order for proper radio reception. But realize this; it only NEEDS to be powered when the AM/FM tuner is the CURRENTLY ACTIVE source playing on your new head unit. Switch the source to CD or DVD or USB or Bluetooth, etc. and it no longer needs to be powered on. Many (but not all) aftermarket car stereo manufacturers realize this and have incorporated features into their head units to address this. I’ll give you two examples of this:

First, look at your "Harness A". Does your harness have a blue wire with a white stripe? Does your harness have a solid blue wire with no stripe? Does your harness have BOTH a white-striped blue wire AND a solid blue wire? Both of those wires are +12 volt OUTPUTS from your new aftermarket head unit (if indeed your “Harness A” has both wires). They are very similar in appearance and function, but the difference between these two wires is WHEN they supply their +12 volt power to whatever they are connected to.

EXAMPLE #1: “Harness A” of my Alpine head unit has two +12 volt, turn-on OUTPUTS. It has BOTH a solid blue wire AND a blue wire with a white stripe. The SOLID BLUE WIRE connects to a power antenna, and will ONLY supply +12 volts when the source is switched to the AM/FM tuner. If any other source is being used, or if I turn off the head unit with its’ power button, or turn the car off using the push-button or ignition key switch, the +12 volts on that SOLID BLUE output wire is de-energized. On the other hand, the BLUE WIRE WITH WHITE STRIPE connects to an amplifier turn-on lead, and will supply +12 volts WHENEVER my Alpine head unit is turned on, REGARDLESS of the audio source that I am listening to. This makes sense as it keeps the amplifier on at all times until I turn the Alpine head unit completely off with the power button, or turn my car off with the push-button or with the ignition key. Note: My FR-S has only a key to start and stop the engine, no push-button. Your vehicle may have either the key or the push-button.

EXAMPLE #2: “Harness A” of my Pioneer Premier head unit has ONLY a blue wire with a white stripe. This BLUE WIRE WITH WHITE STRIPE connects to an amplifier turn-on lead, OR a power antenna, OR BOTH. But just as the Alpine head unit in my first example above, WHENEVER my Pioneer Premier head unit is powered on, and REGARDLESS of the source, this blue wire with white stripe will continue to supply +12 volts to whatever it is connected to, and will de-energize ONLY upon turning the head unit off or turning off the car. Pioneer in this case, has elected to design their head unit to power on BOTH an amplifier AND a power antenna simultaneously with one +12 volt turn-on OUTPUT. It’s not right or wrong to design their head unit this way, it’s just more simple for them to do so.

What do these two examples show?

A) If you were to properly install my Pioneer head unit into a vehicle that has a telescoping antenna along with an amp or multiple amps, your amp(s) would stay on and your antenna would stay up no matter what you were listening to as a source.

B) If you were to properly install my Alpine head unit into the same vehicle, your amplifier(s) and telescoping antenna are able to operate independently under the certain circumstances as described in EXAMPLE #1 above.

Clearly, Alpine has a feature advantage over Pioneer in this case.

But what exactly IS the advantage that the Alpine head unit has over the Pioneer head unit? Let’s say you want to run your car through an automatic car wash but don’t want your telescoping antenna to get damaged from the rotating brushes. If you have the Pioneer head unit referenced above installed in your vehicle, you will have to turn the head unit completely off so that your antenna will retract so it won’t get damaged and in doing so, you won’t be able to listen to any music at all through the duration of the wash. However, if you have the Alpine head unit referenced above installed in that same vehicle, you won’t have to turn your head unit completely off during the duration of the wash and can still listen to any other source OTHER THAN AM/FM radio, because your antenna should automatically retract upon playing the alternate source. Your amplifier(s) will still remain on while the antenna retracts. Kind of a neat little feature, huh?

Now you’re thinking, “Alright, (Michael Knight - Magnum P.I. - Sonny Crocket) why are you telling us this when, again our cars don’t have a telescoping antenna to get damaged?

Well, the aftermarket head unit manufacturers (and the aftermarket harness adapter manufacturers to some extent) don’t know EXACTLY what kind of car you are installing your new head unit into and whether that car has a factory amp, an aftermarket amp, no amp at all, or a telescoping antenna or an amplified shark-fin antenna, or a standard fixed-mast antenna, or an amplified fixed-mast antenna, or no antenna at all. There are simply too many factors involved, so they supply you with all of the (standard) amp and antenna options that they can think of to integrate your new head unit into your existing sound system. But this in turn can sometimes create some confusion when it comes to wiring up your system, and hence, you have amplifiers that don’t power up or antennas that don’t seem to work properly. I also have to place some of the blame on the vehicle manufacturers and the harness adapter manufacturers for not always providing accurate information to the public on the pinouts of their molex plugs.

The aftermarket car audio wire color standard, which both head unit manufacturers and adapter harness manufacturers have had adopted for many years for the most part, is a known standard throughout the car audio industry, with SLIGHT differences between each of the head unit manufacturers and of the harness manufacturers as I have explained in EXAMPLES #1 and #2 above. Actually, Pioneer held onto their “special” color coding system for quite a while even after all of the other aftermarket manufacturers had migrated over to the standard that we know today, but that’s a story for another day.

Always remember this though when it comes to modern aftermarket head units:

A BLUE WIRE WITH A WHITE STRIPE is intended to be a +12 volt turn-on OUTPUT lead which can be used to turn on an AMPLIFIER or a POWERED ANTENNA or BOTH simultaneously.

A SOLID BLUE WIRE is always going to be intended to be a +12 volt turn-on OUTPUT for powering on an ANTENNA only. It is NOT for turning on your amplifiers. If you connect this lead to your amplifier turn on lead, your amp may shut off when you switch to a source other than the AM/FM tuner. It may not even turn on at all if you have a different source ready when the head unit turns on when you start your vehicle up.

So now that you have been thoroughly educated and possibly mildly entertained, here are two scenarios for the problem(s) you may be experiencing after your installation, and the reason why you are reading this:

SCENARIO #1: If you have NO SOUND OUTPUT from your door speakers, and they WERE working PRIOR TO the installation of your new head unit AND your dash speakers ARE working, then you can be sure that you have properly connected the white and gray speaker wires of “Harness A” to the white and gray speaker wires of “Harness B”, (you did make sure that the plus and minus wires are matching, so that your speakers are in phase, right?) which supplies the front audio signal to your factory amplifier, through “Harness C”. The issue is most likely due to the fact that your factory amplifier in the trunk which powers only those two front door speakers is not being turned on by your new aftermarket head unit via the new head units’ BLUE WIRE WITH WHITE STRIPE. The factory amplifier turn-on lead for our cars resides in “Harness C” and eventually must be energized with a +12 volt supply from the OUTPUT of your new aftermarket head unit to turn on your factory amplifier.

SCENARIO #2: If you are experiencing BAD OR NO AM/FM TUNER RECEPTION, but had good reception PRIOR TO the installation of your new head unit AND you have made sure that your “Antenna Adapter” is properly connected to the “OEM Antenna Plug” and also properly connected into the back of your new aftermarket head unit, the issue is most likely due to the fact that the amplified antenna turn-on lead is not being energized at all. The antenna turn-on lead for our cars resides in the “OEM Antenna Plug” and you probably haven’t connected either a SOLID BLUE WIRE or a BLUE WIRE WITH WHITE STRIPE from “Harness A” to the partner wire inside the plug of the “Antenna Adapter” and eventually through to the partner wire inside of the “OEM Antenna Plug”. This partner wire must be energized with the +12 volt supply from the OUTPUT of your new aftermarket head unit to turn on your amplified antenna for you to receive decent radio reception.

Using the knowledge that you have acquired in this write-up, re-check your turn-on OUTPUT circuits and make any necessary changes and this will probably clear up the issues that you are experiencing with your new head unit install into your FR-S, BRZ or 86, Hopefully this write-up has answered any questions you might have had or didn’t know that you needed to ask and helped you solve your problem, but there is more information I have below and you may want to continue reading. (You experienced installers will appreciate this.)

When it comes to the adapter harnesses (“Harness B”), I have seen examples of these harnesses that have SOLID BLUE wires inserted into the body of a plug where it should have been a BLUE WIRE WITH WHITE STRIPE installed into it instead, or even vice-versa. The same goes for the blue wires of the “Antenna Adapters”. Whether it is a mistake on the part of the harness or antenna adapter manufacturer or whether it was intended, I still find them out in the field and sometimes it leads to confusion. It’s most likely due to the fact that many manufacturers use the same pin on their OEM harness (“Harness C”) connector plugs throughout their line-up of different models of vehicles for both the amplifier turn-on leads and the power antenna turn-on leads. I just want you to be aware of this. With the information contained here, and since I specifically stated which blue wire from your new head unit should go to where in our particular cars, you should have no problem whatsoever diagnosing your particular issue.

One more note, never allow the blue OUTPUT leads of your new head unit to contact chassis or the head units’ ground while the deck is powered on or you may blow a fuse at best. You could destroy the turn-on circuit inside your head unit at worst and you don’t want that to happen.

Good luck everyone.

Disclaimer:
The facts represented in this write-up are what I believe, to the best of my knowledge, to be true and accurate. They are based on the USDM version, 2015 Scion FR-S base model and may not be applicable to your particular model year of vehicle. If anybody has any knowledge whatsoever that is in conflict to what you have read here, please don’t hesitate to make it known so that corrections can be made. I am always open to suggestions and corrections. P.S. I apologize for the quality of Diagram #5. I was too lazy to pull the head units out of my dash to snap a good quality picture of the antenna plug so I lifted that image from an older post here and increased the size. Kudos to “thriller” who (originally?) uploaded it.

Diagrams have been relocated to their relevant positions under their descriptions.

[FR-S2GT86]

Bump. Made some edits and rearranged the diagrams to eliminate the need to scroll all the way down the page to see them.