I have put in an aftermarket stereo into my car. (Pioneer DEH-4500BT).

I hooked it all up ok and it was all working. However i noticed that it did not turn off with the engine.

Before i had brought it i had read up about changing stereos so i knew what this was.

I got a friend of mine to wire the Cigarette lighter to the "Switched 12v".

Now it turns on and off with the car.

However, when i turn off the car and leave it for about 30 minutes, the radio stations that i have saved disappear.

Is there any way to fix this?

The car is a Citroen C3 - 1.1i Petrol - 2004 (04).

PS. My friend is a Car Electrical Specialist, but has gone on holiday for a month today!! He also checked correctly which one was permanent live and which was switched live.


You need to make sure that the head-unit is hooked up to constant power (usually the yellow wire on the harness). Make sure that it isn't hooked to a circuit that goes off after half an hour or when you open the door.

  • Exactly, you need to get a constant power to keep the memory between each shutdown/start-up. The constant power wire will draw really few amps that will not drain your battery. Jul 29 '13 at 18:30
  • Some cars don't have a "constant power wire in the audio system loom. I had the same thing with my Opel Corsa. The guys who installed the system had to run a new wire from somewhere. Jul 30 '13 at 7:47
  • It is all wired correctly. The constant and the switched were both tested with a volt meter to check which ones were which
    – Dr.Pepper
    Jul 30 '13 at 9:52
  • 1
    @Dr.Pepper chances are that the constant power isn't actually a constant power. Maybe a 30 minute power. Where are you getting the lead from a random loom or fuse box?
    – Mike Saull
    Jul 30 '13 at 13:21
  • hi mate, the switched 12v is coming from the cigarrette lighter and the constant is coming from the original loom with a harness on the end which came with radio
    – Dr.Pepper
    Jul 30 '13 at 19:17

From the manual:



Black to Ground

Yellow to "always on" (battery, fuse protected) {saves memory}

Red to ignition

Blue/White to external amplifier (or insulated)

Orange (optional) to park lights

  • It is all wired correctly. The constant and the switched were both tested with a volt meter to check which ones were which
    – Dr.Pepper
    Jul 30 '13 at 9:51
  • If, after half an hour or so, the yellow wire is still at 12V (or better) and the radio ground is solidly connected, I'd suspect a faulty radio. Let us know!! :) Jul 30 '13 at 16:05
  • im gonna get the volt meter out and have a check i think at some point lol
    – Dr.Pepper
    Jul 30 '13 at 19:18
  • I'd be grabbing the voltmeter about the second or third time I had to reprogram in the stations!!! (grin) Jul 30 '13 at 21:17
  • Had a go at it with the multimeter. The constant live seems to turn off after about 5 minutes for some reason. Any ideas why that might be?
    – Dr.Pepper
    Jul 31 '13 at 22:54

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