No 12v Phantom Power from Head Unit

[pwbrooke]

Investigating poor reception, found no 12v being injected into antenna co-ax, meaning the active anetnna is not generating any signal to the radio. Any ideas?

[mickthemaverick]

I have moved this topic to the audio section. You have more chance of getting some answers here.

[Paul-R]

Is this a recent problem?

[pwbrooke]

>Is this a sudden problem?

Not sure, only just started to listen to the radio, before always listened to "my music".

Everything else seems to work fine.

Radio reception improves when I just stick a long wire in place of the antenna under the headlining below the antenna. Looking at all the informaiton I can find, there should be 12v generated by the radio into the antenna wire - but there isnt - I tested it on the antenna "socket" on the back of the head unit.

[Paul-R]

I suggest that you check the configuration of the radio is correct using Diagbox to make sure that the option to supply 12v to the antenna is checked.

[pwbrooke]

Thanks, Ill see if I can find this.

[pwbrooke]

>I suggest that you check the configuration of the radio is correct using Diagbox to make sure that the option to supply 12v to the antenna is checked.

Thanks for your good suggestion. Unhappily Diagbox is not cheap.

I've installed a replacement antenna and all works well.

I disconnected the antenna and measured the "phantom" power. It flicks up to 12v for a short time and then drops to zero when the antenna is disconnected. I suspect that there is something to detect if the active antenna is installed and only supplies 12v when this is connected.
But as all is now working I think I am good.

Just for my personal interest, I'd like to know if there is a freeware version of Diagbox that I can just use to check the radio configuration (using the cheap Chinese Bluetooth ODB connector), otherwise I wont bother as all works well now.

[Paul-R]

The software is generally available at different various levels free of charge (if you know where to look) but whether it would work with a Bluetooth ODB I don't know for sure. I severely doubt it though.

There are other softwares available for Bluetooth ODBs but whether they could get inside as deeply I don't know. Again, I rather doubt it.

[pwbrooke]

Thanks Paul,
I suppose I was hoping someone would say use xxx software which reads and writes hex values to the ODB interface and command 0A reads the Infotainment config parameters and 0B writes it back - bit 23 is the "turn on 12v to antenna". But I guess this would be too simple. But as it works I'm not going to do any more that could damage the ECU. Thanks again for your sage advice.
P