The turn-on wire (also referred to as the remote wire) is a Blue wire (typically with a white stripe) located behind the head unit. Its main function is to “tell” your amplifier to turn on whenever the head unit is powered up (usually, whenever the vehicle is turned on).
Almost every aftermarket head unit has a remote turn on wire. The lack of this remote turn-on wire in most stock radios is one of the main reasons why most people are looking for a way to turn on their aftermarket amp without it.
In this article, we’ll take a look at the different ways you can use to turn on your amp without a remote wire. This will come in really handy when you’re hooking up an aftermarket amp to a stock radio.
First and foremost, it must be noted that most car stereos’ wiring harnesses have both a Blue wire with a White strip and a solid Blue wire. The former is the remote turn on wire, while the latter is typically for power antenna or factory amplifier turn on. That said, do not confuse these two wires.
Both of these wires have an output of +12 volts, however, in newer vehicles the power antenna wire will only output 12 volts when the radio is on. Therefore, if you were to hook up your amplifier’s remote terminal to the antenna wire then your amp would only be running when the radio is on. If you switch to CD, satellite radio, USB, Aux input …etc, the head unit will turn off the power antenna wire and your amplifier will turn off as a result.P.S: In some older vehicles, substituting power antenna for remote turn on wire was very common and worked great because in those vehicles when the radio was on, the power antenna was up and working as well.
With all of that being said, understanding what a remote turn on wire does and installing it correctly will ensure a good functioning of your sound system, and prevent unwanted current draw on the battery when the audio system should be off.
What Does The Remote Turn On Wire Do?
Essentially, the remote turn on wire receives a turn on signal that’s +12 volts DC from the electrical system when the ignition is in the accessory or on position. This turn on signal is transferred through the remote turn on wire to the amp’s turn on circuit; when the amplifier senses this voltage, it turns on. Likewise, when there’s no voltage in the wire (meaning the ignition is off), the amps turns off.
If you tape into an existing wire in your vehicle that has constant voltage and connect it to the remote turn on wire, your amplifier will always be on.
On the same note, if you tape into a wire that does not receive voltage when the ignition is in the ACCESSORY or ON position and you connect it to the remote turn on wire, your amplifier will not turn on until that wire does receive voltage.
On a different note, if the remote turn-on-wire isn’t installed correctly, your amp will not turn on when the headunit is powered on even if it has good power and ground connections, or it may keep drawing power until the battery is drained of power.
5 Ways to Turn on an Amplifier Without Remote Wire
As we’ve mentioned earlier, there’s a number of different ways to get your amplifier to turn on and off remotely even if your head unit does not have a remote turn on wire.
We’ve listed all of them from favorite to less favorite. So, We highly recommend the top ones.
1. Get the Turn-On Signal from Your Vehicle’s Fuse Box
Getting the turn-on signal from your vehicle’s fuse box is one of the best ways to make an amplifier turn on without the need for the stereo’s remote turn on.
Since the remote turn on wire is low current, you can connect it to almost any fused output terminal, like the one for the radio itself for instance, as long as it only powers up when the vehicle’s on.
Before connecting the wire to the fuse, use a multimeter to make sure the fuse you’re getting the signal from only receives voltage when the ignition is on.
Using an Add A Fuse connector plus a 2A to 10A fuse will make this connection much easier.
2. Use a Remote Turn-on Module/Trigger
A turn on module is as its name suggest a small device that’s used to provide a turn on signal to your amplifier. It can be activated directly from any speaker wire or low-level trigger lead.
When installed, a turn on module will sense the voltage on the head unit’s speaker wires and then send a +12 volt signal to the remote wire.
The best things about most of these turn-on modules beside the fact that they’re inexpensive, is that they incorporates a few seconds delay before triggering the output in all applications to prevent turn-on noise (in the form of loud pop).
3. Use High/low Adapter with Trigger
Using a high/low adapter with trigger (also known as line output converter or LOC for short) is another great way to turn your amp on without the need for a remote wire. Basically, what this adapter does is that as soon as the head unit turns on, it’ll sense that and gives you a remote output that will trigger your amplifier to turn on. Likewise, when you turn the radio off, or when you turn the ignition off, it’ll see no signal from the speaker level wires it’s hooked up to and kills that trigger.
Essentially, a line output converter is a device that is usually used to convert the non pre-amp speaker output (high-level signals) from a factory head unit into a low level signal that is suitable for an aftermarket amplifier.
4. Use a Source That Turns On/Off with the Ignition Key
Since stock radios don’t have a remote turn on wire like aftermarket ones, the voltage turn on signal has to come from somewhere, and that somewhere is definitely the electrical system of your vehicle.
That said, find a voltage source (part of the vehicle’s electrical system) that only turns on when the ignition is in the ACCESSORY or ON position, tap into it, and connect the turn on wire to it. It’s as simple as that.
5. Wire a Remote Turn on to a Switch
Another decent option for wiring a proper remote turn on wire to your amp is to run a constant power wire and ground to a switch and then wire the output of the switch to the amplifier’s remote turn on. What this does is that it allows you to manually control when the amplifier turns on and off by the flip of a switch.
The downside to wiring the remote turn on this way is that it’ll keep working even when the vehicle’s electrical system is not charging. Therefore, if you forget to turn off the switch, the amplifier will keep drawing power until the battery is dead.
6. Run a Jumper Wire from Power to Remote Turn on (NOT RECOMMENDED)
This is the easiest way to do a car amp remote wire bypass. However, it’s not recommended at all.
If we don’t recommend using this method, then why did we list here? Well, for one simple it reason, it could work as a temporary workaround. But it shouldn’t be used as a long term solution.
To put it simply, this bypass consists of running a jumper wire from the power terminal to the remote turn on terminal (as shown in the image above).
Doing this, your amp will be receiving constant voltage, and will keep running and will never turn off until it blows out or until it drains the battery.
How to Test Your Remote Turn on Wire
To test if your remote turn on wire is functioning properly, use a multimeter and place the positive lead on the end of the remote turn on wire and place the negative lead of the multimeter to a grounding point.
With the ignition in the OFF position, there should be no voltage.
Put the ignition in the ON position and and test the same way again. There should be 12+ volts at the remote turn on wire.
If the multimeter shows that the remote turn on wire has 12+ volts while the ignition is OFF, it’s undoubtedly connected to constant power.
If the remote turn on wire doesn’t have voltage while the ignition is ON, it either doesn’t have a good connection or isn’t connected to a wire that receives voltage when the ignition is ON.