I'm installing an aftermarket stereo and was thrown off when I found 2 12v constant wires... The next day my battery was almost drained and I knew it had something to do with the wiring. Can someone help me fix my wiring issue? The stereo is a Sony DEH150MP (already snipped off the factory harness due to the fact I don't plan on going back to the original stereo since its dead) I think my issue is I combined the 2 12v constant power? Or maybe screwed up the constant and switch? Thanks for the input

 

Sony or Pioneer? every reference I look at for DEH150MP says Pioneer.

I dont think anyone can fix your wiring issue as we have no clue what you have done. Its hard to imagine a scenario installing a standard head unit that will discharge a healthy battery. It may well be a co-incidence and thats the time it decided to die.

You can have up to 3 x 12V sources normally. One permanent, one switched with ignition, one switched with lights (this last one is not used on all system and is used for dimming at night)

What I normally do when I have no documentation (assumes you have a multimeter):

To identify car harness:

Turn the ignition off, test each lead until you find an earth (label)
Ignition still off , test each remaining lead until you find 12V (label)
Ignition on, test each remaining lead until you find 12V, check it goes off/on with ignition (label)
Lights on, test each remaining lead until you find 12V, check it goes off/on with lights (label) Note: not always present on all cars, some just use the two x 12v above
Ignition on , apply 12V to each remaining lead (best done with a jumper lead which includes a low amp fuse) if aerial operates that is the antenna wire (often blue, label) Skip this step if you have no power aerial
You should now be left with a bunch of speaker wires, typically in pairs one with a colour and the other with the colour repeated with a trace colour (often black). You will have at least two and possibly four of you have front and rear speakers.
Use an AA battery across each pair to identify which pairs go to which speakers, you will here a light thump in the speakers as you contact the battery (label)
Any spare wires , insulate and tuck away.
When you connect speakers be consistent about which wire is +ve or -ve (ie colour or colour with trace) its affects sound quality.

 

My apologies, it is a Pioneer head unit. I got all the speaker wiring correct and such but I think I may have mixed up the switched and constant. Are you supposed to combine the two constant 12v to the 1 lead into the head unit harness? My car has the power antenna equipped but it is broken and I didn't bother to connect it. I also noticed that every time I turned the unit on it prompted me for setup. Does that mean there could be a mix up with the constant connection? I'll go ahead and do the multimeter test and see if I can overcome it because Jaguar wiring just has to be a headache haha. Appreciate the feedback!

 

Car Audio Wire Diagram Codes Jaguar - Factory Car Stereo Repair - Bose Stereo, Speaker / Amplifier Repair 1995 Jaguar XJ 6/ XJ 12 Car Stereo Wire Colors
Are the two guidelines I used as far as wiring diagrams.

 

Sounds exactly like you have the switched 12V and the permanent reversed, its easy to do. All your set up is being lost when you turn off the ignition.

No there is no need to combine the 12V leads, one is plenty. Just make sure of two things. Firstly that the constant 12V is there with everything off, and secondly that you protect the end of the one you dont use (either shrink wrap the end or fold it back on itself and wrap it in insulation tape) If you dont it will find something to short out to.