Radio malfunction

Hi
Grateful for advice on frustrating problem with radio/cd player which I had to remove to sort out other problems in the dashboard.
Problem is this: radio will not switch on, but on pressing the display and cd eject buttons it springs into life (no sound) for a few seconds - then nothing.
There is constant power coming from the car side of the radio. Turning the ignition key to accessories or full on makes no difference.
Tried a similar wiring loom to see if that would make any difference also changed the radio to an identical model. Again exactly the same problem - live for a few seconds on pressing the display /eject buttons.
Before dismantling I noticed (I think!) that the radio clock display came on only when the radio was switched on - that is it was not displayed when the ignition key was turned.
You May have guessed from the above that I am not comfortable with car electrics, so if you think you can help please don’t assume any expertise on my part.!
Grateful for any advice.
Cheers
Dengeo
 

Does it need a code after being disconnected?

Is it a face off model? Might not be locking in correctly until you apply pressure when pressing the buttons you mention or perhaps the electrical connections between face and set are dirty/worn

No code required.
No problem with detachable heads - two identical radios used to test.

Did you check the fuses on the back of the Radio or the fuses in the fuse box?

Newer radios require 2 B+ voltages.  Once for the presets (constant 12v) and one switched.
I would think that you have a missing voltage.

Hi Briano
I checked the fuse at the back of the radio and the fuse number 3 in the fusebox, which relates to the radio etc. Both are ok.
Is there another fuse(s) which I need to check also?
What does B+ mean? Please excuse my ignorance of these terms.
cheers
dengeo

B+ refers to the input Positive voltage to a Circuit or Device, if I said +12 well that all depends on the state of charge of your battery as it could be 12, 12.5, 13.5V.

B+ is a Electrical term…sorry I have been in electronics for years.  

On some radios there are 2 fuses, and some but one.

If you wire or jumper the Yellow, and Red back to the battery then does it work with the jumper?  As it sounds as if you have missing a Ground or Positive voltage to the unit.    

I have also seen Radios that needed the Antenna Grounded, and others that if the antenna is grounded wouldn't power on.

I googled the JVC KD G11 and found installation instructions as well as Circuitry repair.  If you have 2 Radios doing the same thing, then usually its the wiring.

Unless you have 2 dead radios.

Hi Briano
Just so that I understand.
Should I join the male plug from the back of the radio (containing the speaker wires) to the female plug as normal?

Then, without joining the other male plug from the back of the radio to its usual female plug, should  I  use a spade connector to join a wire to the yellow wire terminal (in the male plug)  and run it to the positive terminal of the battery; and another similar wire from the  red wire terminal in the plug back to the positive terminal of the battery. And then check if the radio works?
sorry to be a pain but these electrics are a complete mystery to me !!.  

https://www.manualslib.com/manual/606400/Jvc-Kd-G111.html

You may need to reset it if you connect it up correctly.

installation instructions.

https://www.manualslib.com/manual/488836/Jvc-Kd-G111.html?page=2#manual
shows you how to wire it up.

Black to ground
Red is switched power (Defroster black/yellow works) +12V Switched power one with the ignition on.
Yellow is +12V live (constant power) 12V+ to ground with the ignition off
Blue to the power antenna or rear amp.


Striped wire is the negative for the speaker, where as the solid color is the positive side of the speaker
White/Black -  white  front left speaker
Gray/Black - Gray        front right speaker.
Green/Black - Green rear left speaker
Purple/Black - Purple rear right speaker

You may need to get a Sachs or Scosche, connector to wire in newer radios to older VW chassis, so you don't have to run new wires, it should be soldered and heat shrinked, but if you must Crimp, stagger the connections so you don't have all the connectors in a bunch… The Staggered makes it easier to bend and fold, If I was going to use Crimps, I would also wrap them with Friction tape.

 

Hi Briano
Many thanks for taking so much time to give me advice. I really appreciate it.
best wishes
dengeo

if its a late cab the switched feed is fed from the ignition switch pin SU, if so the radio comes on when you insert the key.

if it used to turn on with the ignition key turned then its had a switched feed fed from somewhere else, you'll have to check your wiring to find out where