Car Stereos: Sony MEX BT2700 Memory resetting, vw golf rabbit, butt connectors

Question
QUESTION: Hi there,
I've just installed a Sony MEX BT2700 XPLOD Stereo into my 96 VW Golf / Rabbit.  The stereo works fine but each time I leave the car the stereo loses all of my user settings like radio station and audio settings.  When I installed it I had an older Sony stereo in the car already so could just replace the wiring looms in the same connectors without fiddling with the wiring at all. I understand from reading a few forums that I may have the red and yellow ignition and battery connectors the wrong way around in my set up so the unit is losing all power when I switch off the ignition.  If I just switch around the order of these two wires in my setup will that resolve my problem?

Do i just need to get hold of a couple of standard connectors from an auto shop and swap the two wires over myself.  Could doing this cause any problems or is it a straightforward job of swapping the two wires over.  

Hope you can help and thanks in advance.
Cheers,
Mark

ANSWER: Hi Mark,

Yes, that's the likely problem.  Your constant & switched power are reversed.

If you're using an aftermarket wire harness, then the red and yellow will likely not be connected correctly.

The correct way (in my not so humble opinion) to connect two wires is to solder and heat shrink.  Others use vampire clips, some use butt connectors, there's many schools on it.

As long as you make a clean connection and don't leave any wires exposed, you're good to go.

Justin

---------- FOLLOW-UP ----------

QUESTION: Hi Justin,

I've just tried switching the yellow and red cables and with this setup the stereo wouldn't power up.  I switched it to the setup in the manual for cars without ACC position with the yellow and red cables from the car both running into the yellow cable and the stereo now holds its memory when I switch off the ignition.  When I leave the car however and the cars immobilizer kicks in the power to the stereo is still being cut and when I return to the car the memory is wiped again.  I think it must be the immobilizer that's cutting out power but I was just wondering if there was a way around this or if the immobilizer in my car is set up in such a way that the cars electrical circuits are completely closed when it is active.
Hope you can help.
Cheers,
Mark

ANSWER: Hi Mark,

What you're saying would suggest that whoever installed the immobilizer cut something they shouldn't have.  If it's a factory one, then I'm not sure what to tell you.

The constant should be a constant.  Period.  24/7.  If it isn't, it might be time to run a new fresh wire off the battery fused straight to the deck.

Justin

---------- FOLLOW-UP ----------

QUESTION: Hey Justin,

Things have moved on a little and I tried to edit the question I  asked but couldn't work out how. I've eliminated the immobilizer now because the constant was still powering the stereo when the immobilizer was active.
The stereo stopped working completely and I worked out tha the radio fuse had gone in the car which I replaced.  When I did this the stereo still wouldn't power up so I went back and switched the red and yellow cables and I had success. The stereo now receives constant power and doesn't lose memory when the car is switched off.  This works some of the time but not always.  When I start the car it is hit and miss whether the stereo powers on and whilst it does sometimes, it doesn't always come on with the ignition.  It probably powers on 50:50 and if it fails the stereo is completely unresponsive until the ignition has been turned off and back on again.  I tested the stereo unit at a local auto store and it worked fine so the problem must exist somewhere in the wiring set up in the car.  The constant supply seems to be working fine now because I have not lost memory power since I switched the red and yellow wires as you suggested. Is there another fuse in the vehicle linked with the stereo that may need replacing anywhere? The interior lights and everything seem to be working normally and I'd assumed any other fuse may be linked to those.  

Occasionally if I go over a speedbump the stereo will also lose power and it will restart itself which makes me feel there may be a lose connecion somewhere that is causing the problem but I have no idea where it could be and I have checked all the connections into the back of the stereo a number of times.  It's really got me stumped and anything else you can suggest I try before I bite the bullet and take it to an expensive stereo installer would be much appreciated.

It's doing my head in having to sometimes restart  the ignition 2-3 times each time I start the car so that I can listen to some music while I drive.
Hope you can help and thanks again,
Mark  

Answer
Hi Mark,

If it comes on sometimes, but not others, that would almost certainly rule out a fuse.  A fuse either works, or it doesn't.  Rarely does it go and come back sporadically.

You're definitely dealing with some loose wiring.  When you tested the deck elsewhere, did you use the harness that had it plugged into your car?

I ask this because maybe the connectors inside the harness are getting loose.

Unfortunately, I can't give much guidance beyond that, because the only thing you can reasonably do now is work your way down the wires and find where the corrosion/bad connections are.

Justin