Radio won't power up without the aerial connected

[Pond]

As per the title.......why?
I have a new stereo for the car and thought I would check it works today. The connectors are the same as the old one; previous was an Alpine aftermarket and new is a JVC, but I don't have an aerial extension connector so thought it would be OK. I couldn't get the new one to power up. So I plugged in the old Alpine and with the aerial connected it works fine but without it won't fire up either.

The weirdest thing is that with either connected and the aerial unplugged, there is a constant 'clicking' from the PCB in the nearside footwell speaker.

I can't see how the aerial has anything to do with power to the radio, as it has it's own earth.

I hate 12v DC, it doesn't make any sense to me!

 

[Stevo7682]

Stab in the dark (as,its only thing I can think of )
Get a length of wire plug radio together without aerial (so in not working mode) then run wire from known good earth to radio external casing if works you have an earthing issue somewhere and the unit trying to ground through aerial .
Stephen

 

[Pond]

Stab in the dark (as,its only thing I can think of )
Get a length of wire plug radio together without aerial (so in not working mode) then run wire from known good earth to radio external casing if works you have an earthing issue somewhere and the unit trying to ground through aerial .
Stephen

Good idea, thanks.

 

[Rudyrov]

The radio is getting ground through the antenna shield wire is the most likely scenari.
It is ok and wont hurt anything, there should be a ground wire in the radio harness, perhaps it’s not connected or not used. There are a variety of reasons for this including unwanted radio noise control or ground loops.

 

[Pond]

The radio is getting ground through the antenna shield wire is the most likely scenari.
It is ok and wont hurt anything, there should be a ground wire in the radio harness, perhaps it’s not connected or not used. There are a variety of reasons for this including unwanted radio noise control or ground loops.

Looks like this was the case. I had no earth to the radio in the wiring loom from the car, although there was a wire connected (but it isn't brown!).
So I have diverted the earth from the radio connector directly to an earth post on the car. Sorted and works a treat.

Many thanks guys.

I also have a blown rear speaker, so I am going to replace both rears. I just hope the dodgy radio wiring isn't the cause of the speaker blowing.

 

[Duncodin]

Look at the wiring diagram. The radio earth wire goes right back to the bracket of the aeriel. If that wire isn't connected to the frame then i guess your only earth is the shielding of the ariel cable.

Some people may, over the years, have earthed their radio somewhere under the dash but from the factory it's that long brown wire going to the aeriel bracket.

 

[Pond]

Look at the wiring diagram. The radio earth wire goes right back to the bracket of the aeriel. If that wire isn't connected to the frame then i guess your only earth is the shielding of the ariel cable.

Some people may, over the years, have earthed their radio somewhere under the dash but from the factory it's that long brown wire going to the aeriel bracket.

As I said I have a wire in the loom connector where the earth should be but it isn't brown (can't remember the colour and don't really care).
It looks like the loom has been modified, presumably when the aftermarket stereo was fitted. I don't know and am not going to pull apart the loom just for the radio. A radio, for me, is just an added bonus; not critical to my build.

I now have it all working with the aid of some new rear speakers (luckily I have a Halfords 300 yards away). The radio doesn't work as I know my aerial is knackered. I may, or may not, look at that in future. I can play music through a USB stick which is enough for me.

I only tested the stereo to make sure it fits behind the new dash in the glovebox. I had to buy a 'short chassis' head unit but it was still very tight. All good, all fits and all works. Onto the next problem!