Hey guys,

Have just been doing some tinkering and something's got me completely stumped.

I have a VT2 Calais with a Pioneer AVH-P6850DVD double din head unit. Now, at one stage last year i was also running another head unit at the same time as an experiment. Both wiring harnesses for the Pioneer and the Alpine (other head unit) were spliced into the stock loom.

Now that the Alpine is long gone i'v been meaning to take out it's wiring loom to clean up the tangle of wiring in the car. So i did just that today. However, somehow in the process i have ended up doing something, leaving the Pioneer unable to turn on. Now i'm hoping it's a wiring issue and not the Pioneer unit itself, not that i can possibly imagine how i would have killed it as it was disconnected the entire time.

Anyway, i'v misplaced all my wiring diagrams and would appreciate some help. In the stock loom, there are two main "branches". One of them was being completely unused for the head unit for the last 18 months so i figure it's not needed but i'll list the colours anyway:

Unused plug: (WTF is this plug for? I really cant remember)

- Black w/ Yellow stripe
- Purple
- Black w/ white stripe
- Orange w/ black stripe
- Brown

Now, on the main bit of the loom, i'm using about half of the wires whilst the other ones arent being used as i'm running RCA's for my front stage and sub.

Main loom (USED):

- Black w/ white stripe (Ground)
- Orange w/ Black stripe (Constant 12v)
- Yellow (ACC)
- Blue w/ black stripe (Speaker)
- Blue w/ Orange stripe (Speaker)
- Brown w/ Black stripe (Speaker)
- Yellow w/ Blue stripe (Speaker)

Main loom (UNUSED):

- Yellow w/ red stripe (Power aerial)
- Light green (FR)
- Dark green (FR)
- Light brown (FL)
- White (ANT Up)
- Light blue (ANT Down)
- Grey (FL)
- Yellow w/ black stripe (Phone Mute)
- Grey (Dimmer out)
- Brown w/ White stripe (Dimmer In)

Ok, so that's how the Pioneer unit is wired up now (and for the past 18 months i might add working perfectly) and now it refuses to power on.

WTF am i missing? Have i ****ed something up?

So the Pioneer doesn't power up at all is my understanding?

If that's right, then check the constant, accessories and ground wires. Test to make sure there is current (12v+) coming through them when the ignition is on (for accessories wire) and all the time for the constant wire. And make sure that the wires are connected solidly.

If there's no voltage going through, then check the wires are properly connected to the battery etc, and also check that you haven't blown or partially blown a fuse.

Ok so i checked the head unit by wiring up the constant and ACC directly to the positive terminal on the batt. I still used the earth in the loom and it all worked fine and powered up.

So, the head unit is fine, the stock earth wire is fine. So this brings me to the conclusion that it must be either the constant or ACC wire in the stock loom. Which is just wierd because it's been working fine for 18 months. Unfortunately i don't have a multimeter so i can't test the wires. Is there any other way to see if there's 12v through a wire?

if you didnt disconnect the car battery you might have blown a fuse, check that first

*nvm didnt see post lol*

go spend $10 on a basic mulitmeter and get yourself a test light whilst you're at it.

yeah thats a good idea, I got some cheapys from sca, my multi has just started to die (and lost the test light), and there usefull