Headunit loses its memory everytime.

jeremywe · Post by **jeremywe** » Mon Mar 29, 2004 10:56 pm

My headunit loses its memory(pre-set radio station, sound adjustment, etc.) everytime i switch off my car for more than 1 min. If i happen to restart the car within about a min or 2, the momory remains...

Its getting on my nerves... Help guys...

Thanks.

btw, HU is a pretty new sony single-DIN model.

Post by **smorison** » Mon Mar 29, 2004 11:18 pm

sounds like a wiring issue, i think you'll find that it wasn't wired in properly

ruchi · Post by **ruchi** » Mon Mar 29, 2004 11:44 pm

The head unit should have two power wires, one which goes to a constant 12v source and one which is connected to your ignition.

The constant 12v source keeps things like the memory alive, while the one going to the ignition turns the unit on and off when you turn your ignition on and off.

Make sense?

It would appear your ignition power wire is fine, but the constant 12v wire either isn't connected, the fuse is blown or is not connected to a constant 12v source (i.e. a source that still provide 12v power even when the ignition is off).

Post by **smorison** » Mon Mar 29, 2004 11:59 pm

ruchi wrote:The head unit should have two power wires, one which goes to a constant 12v source and one which is connected to your ignition.

The constant 12v source keeps things like the memory alive, while the one going to the ignition turns the unit on and off when you turn your ignition on and off.

Make sense?

It would appear your ignition power wire is fine, but the constant 12v wire either isn't connected, the fuse is blown or is not connected to a constant 12v source (i.e. a source that still provide 12v power even when the ignition is off).

.

so happy your around to provide more info that i just don't have time to write

ruchi · Post by **ruchi** » Tue Mar 30, 2004 12:08 am

you're welcome

jeremywe · Post by **jeremywe** » Tue Mar 30, 2004 1:17 am

I have checked both the power cables from the HU.

They have unique plugs to ensure that they arnt connected wrongly i noticed... I have tried to reverse them, but its still the same.

One thing i noticed is that the ground cable was not connected to anything... but even when i tried to hold the earth cable against a metal part of the car... the problem still persist.

Anyone knows that the problem is?

I suspect that the constant 12v wire from my car may not be supplying the power... is that possible? How do i check that, and what should i do if thats the problem.

Thanks again guys.

ruchi · Post by **ruchi** » Tue Mar 30, 2004 10:48 am

A number of devices require power, even when the ignition is switched off (clock, lights, alarm etc.), so there are a number of constant 12v wires to choose from.

If you can't find a constant 12v source nearby, you can always run a wire directly to the fuse box or the battery.

The easiest way to check your existing wire is with a multimeter, but if you don't have one it's as simple as taking a globe out of the dash and connecting one end to the 12v wire and the other to ground (car body). Turn your ignition on and see if it lights up, then turn the ignition off and see what happens.

jeremywe · Post by **jeremywe** » Tue Mar 30, 2004 5:50 pm

Hi,

Thanks for the prompt reply. I'll try that tonight.

Got a few silly questions, pardon me guys, i'm new to all this stuff...

Everything has got to be connected to ground for it to work right? Take the amp for example... Funny thing is that, the ground cable for my HU is just hanging around inside, and not connected to anything at all, how come my HU still works?

Question 2 is, when i pulled out the constant 12v power from my head unit and left the 12v source thats connected to ignition on. I start my car, but the HU does not work. Why is it so? Isnt it supposed to work?

ruchi · Post by **ruchi** » Tue Mar 30, 2004 6:10 pm

jeremywe · Post by **jeremywe** » Tue Mar 30, 2004 11:18 pm

Hi ruchi,

You said,
"12v ignition power is only for the memory backup and only draws minimal power, whereas the normal 12v power lead actually powers the HU and draws a much larger current."

But the funny thing is that when i tried to power up my HU with either of the power cable disconnected, it wouldnt work. It only powers up when both power cable are connected. This proves that both the power cable are working right? But the problem now is that, why the HU cant retain its memory?

This problem even happened before i installed my amp, in which case there was no grouding for the HU. Anther weird thing is that, when i held the entire HU in my hands(not mounted onto the car at all - not grounded) it still is able to power up with both the power cable connected.

Thanks.

ruchi · Post by **ruchi** » Tue Mar 30, 2004 11:50 pm

Sorry, I rushed my response as I was in a hurry and was focused on another task and I ended up saying the wrong thing

what I should have said is:

12v ignition power activates an electronic switch that prevents the unit from being turned on when the ignition is off.

So to clarify the wiring:
1) 12V wire needs to go to a source that will supply power even when the ignition is off. This keeps the memory alive and also powers the unit when you turn it on
2) Ignition wire goes to a 12v source that is only active when the ignition is on. This triggers an electronic switch within the HU that allows it to be turned on, while preventing it from being turned on when the ignition is off

As for the HU not being grounded, quite simply it has to be grounded somewhere or the circuit is not complete. If the antenna cable is plugged in this will ground the HU.

I've removed my previous post to save confusion in case anyone else reads it. Sorry 'bout that!

jeremywe · Post by **jeremywe** » Wed Mar 31, 2004 3:12 am

Thanks ruchi for your prompt and quick replies.

I'll try to figure it out...

WIRE 1) 12V wire needs to go to a source that will supply power even when the ignition is off. This keeps the memory alive and also powers the unit when you turn it on
WIRE 2) Ignition wire goes to a 12v source that is only active when the ignition is on. This triggers an electronic switch within the HU that allows it to be turned on, while preventing it from being turned on when the ignition is off

Just to understand it better... to switch on my HU, the 2 wires has got to be connected. And since this stands true for my case, then it seems like the connections are correct, right? This would also mean that my WIRE 1 is fine right? And WIRE 1 is 'in-charge' of supplying power to the HU when the car is off... But how come my memory goes off?

Sorry for being such a pain...

ruchi · Post by **ruchi** » Wed Mar 31, 2004 11:01 am

Correct, both wires need to be connected, but wire 1 needs to be connected to a constant 12v source whereas wire 2 connects to a source that only supplier power when the ignition is on.

Your memory goes off because wire 1 is connected to a source that only provides power when the ignition is on. Instead it should be connected to a source that provides power all the time, even when the ignition is off.

jeremywe · Post by **jeremywe** » Wed Mar 31, 2004 2:40 pm

Thanks a million, ruchi. I'm getting the bigger picture now.

You've been a great help!

ruchi · Post by **ruchi** » Wed Mar 31, 2004 3:20 pm

We're all here to help