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In my previous cars I could save certain radio stations, volume levels, etc. on my stereo and they would stay saved (unless the battery went dead).

I'm using the same stereo head unit in my latest car but it seems to be starting completely from scratch every time I start the car - any saved settings are gone.

I think the problem is that whatever way car is wired there doesn't seem to be electricity available to the head unit unless the engine is on.

Is there any way to keep power available to the unit all the time?

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Yes, pictures would help. What model is the stereo/car? –  endolith Jun 14 '11 at 1:29
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5 Answers

Sounds like a problem in the way the head-unit was installed. If you had someone install it, take it back and explain the issue, if you did it yourself, double-check to make sure everything is wired up correctly.

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Yup, did it myself. It's the same head unit I've been using in my last few cars - I've connected it using the exact same wiring as before but my current car had some additional wires for some radio controls beneath the steering wheel which I'm not using. Perhaps pictures would help? –  Rob Burke May 9 '11 at 16:53
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Some car wiring systems provide an always-on line, as well as an ignition line. The way these are handled can be different. If your current car has them split out functionally, you may need to wire the always on 12V to your head unit.

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I once had this issue with a new head unit, but it was installed by a shop. I took it back and they explained that the technician had forgotten to connect the always-on wire or something along those lines. I would look for a wire that isn't connected.

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There are almost certainly two different power lines available to, and likely to be needed by, the radio:

  • Always on.
  • Ignition.

The "always on" line always has power available on it. This is what would ensure that the settings in the radio stay on when the car is off.

If you have connected two power leads to the radio, you may have reversed them. If you only connected one, you probably also need to connect another one that is from a line that is always powered.

So, go back and check your wiring: specifically the pinout for power connectors (there should be two of them), and the power supplied from the car to these two lines. For example, see the photo on this page: F150 Radio Wiring Wire #1 is the always on power, and wire #2 is for the ignition. Your radio will likely have the same requirements (though via different pins on the connector). If you have both of them connected, verify that you have the correct ones connected, for example using a voltmeter while you turn the ignition on and off.

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Without knowing the specific make and model of the vehicle, I won't be able to tell you exactly what color wire in the bundle is for the power wire. So you'll have to do some testing to figure it out. All you'll need is a Multimeter

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You'll be measuring between 11 and 18 volts DC, so start by setting the multimeter to the 20 volts DC setting.

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Next disconnect the stereo to expose the vehicles wiring harness.

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Now you'll have to locate the "ground" pin in the harness, or you could use almost any exposed metal in the vehicle (depending on make/model). The "ground" pin will usually be connected to a black wire, but this is not always the case. Once you've located a solid ground connection, connect the black probe from the multimeter to it.

Use the Red probe to test each pin in the harness, making sure to touch only one lead at a time. One of the pins in the harness should read between 11-18V, that's your power (always on) wire.

To locate the ignition wire follow the same steps as above, only this time have the vehicles ignition in the ON position. The ignition wire will be the pin that reads voltage only when the car is ON.

Most modern after market car stereos use the same wire colors.

  • Black = Ground (-)
  • Yellow = Constant (+12V)
  • Red = Ignition (+12V)
  • Orange = Illumination
  • White = Left Front (+)
  • White/Black = Left Front (-)
  • Grey = Right Front (+)
  • Grey/Black = Right Front (-)
  • Green = Left Rear (+)
  • Green/Black = Left Rear (-)
  • Purple = Right Rear (+)
  • Purple/Black = Right Rear (-)
  • Blue = Accessory (power antenna, amp, etc.)

Make sure you connect the Yellow wire from the stereo, to the wire you identified as constant power earlier. If you do not locate a constant power source in the vehicles wire bundle, you can route one from the interior fuse box or splice it from a nearby source. However, you'll want to make sure this new power wire contains an inline fuse of the appropriate size.

Once you have the stereo hooked up to constant power, you should never have to reset your stations again.

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