I'm trying to fit a JVC cd head unit into 51 reg corsa, have connected wiring but unit does not power up. help!!!

If your JVC head unit AV is not turning on and you're getting no sound at all, there could be several possible causes. Here are a few troubleshooting steps you can try:

1. Check the power source: Make sure the head unit is properly connected to the power source and that the fuse is not blown. If the head unit is not getting power, it will not turn on.
2. Reset the head unit: Sometimes, a simple reset can solve the problem. Look for a small reset button on the front or back of the unit and press it with a pointed object like a pen or paperclip. If there is no reset button, you can try disconnecting the power source for a few minutes and then reconnecting it.
3. Check the wiring: Make sure all the wiring is properly connected, including the ground wire. Loose or damaged wiring can cause the head unit to not turn on or produce sound.
4. Check the speaker connections: Make sure the speakers are properly connected to the head unit and that the wiring is not damaged. If the speakers are not properly connected or the wiring is damaged, you will not hear any sound.
5. Try a different source: If you're using an external device, such as a CD player or MP3 player, try a different source to make sure the problem is not with the external device.

If none of these troubleshooting steps work, the problem could be with the head unit itself and it may need to be repaired or replaced.

if it does it when turned up check the power wires and the ground may not have a good connection

Yes, helps to have power on all wires that need power. lol

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Try connecting the yellow wire to a constant power source. That is, a source that still has power when the key is turned off. The yellow wire controls the memory of the radio.

there should be a small connector on the changer itself for the power ground and remote wire for power to the changer unit. the cord coming from the unit to the changer doesn't supply this power and this is why it wont eject and also your head unit wont recognize it until it gets powered up and able to communicate with the head unit and then it will show up as a selectable source when switching between sources of music. check the back of the changer for a small connector containing 3 or 4 pins and you should have a connector with the corresponding wires coming from it to plug into this spot after connecting the wires properly. if you bought it on ebay it is possible you didn't get this piece which is critical when connecting this changer.

IF THIS IS THE PLAYER THAT CAME WITH THE CAR FROM NEW THEN :-
GO TO YOUR LOCAL VAUXHALL DEALER WITH PROOF OF OWNERSHIP OF THE CAR AND I AM SURE THEY WILL HELP.

get a voltmeter(multimeter) and check the voltage on the

red wire
and
yellow wire
(from the car)
when the car is turned off and when the car is on

one should be 0V when the car is off
and both should be 12V when the car is on

then you need to match that up with the radio using the manual

but im guessing that you dont have a manual so...
i want ot confirm that
when you connect red to red and yellow to yellow
nothing happens

try the oposite way

red to yellow yelolow to red

You need to swap the red and yellow round so it dont loose its memory everytime you turn the key off, JVC normally have a fuse that can change position if you want the power on all the time. Check the handbook.

The head unit should have two separate +12V connections: One that goes to a switched 12V power that is switched on/off via the ignition and one that is always energized at +12V. If the head unit's switched +12V lead is not connected, the unit will not turn on (except for when +12V is first applied to the "always on" lead, in which case it will immediately eject the CD). Please respond if this is not the issue. Hope this helps!