A few years ago I replaced the original worn out audio head unit in my '90 Majestic with an A/M Alpine.
The radio aerial mast extends occasionally when the unit is first turned on, However most of the time is doesn't extend, I turn the unit off the mast extends, remains
extended for a minute or so and then retracts. I've connected the aerial in a few different ways and no change; any ideas?

Thanks

 

Hi Roger,

My first suspects would be the ground point behind the right trunk carpeted trim panel, below the tail lamp, and the Antenna Up relay. The Antenna Up and Antenna Down relays are mounted behind the right trunk trim panel near the antenna motor. The relays are driven by the CPU, each with its own control wire. One wire connects the radio to the CPU, and the CPU either commands the Up or Down relay on depending on the voltage on that wire.

Corrosion on the CPU electrical connectors and water on the CPU circuit board are known issues if you've had trouble with blocked drains under your A/C evaporator.

Cheers,

Don

 

Thank you Don, I'll check those connections and ground points.

 

the aerial moves on a pulse signal, its not permanent from the original jaguar stereo , the jaguar stereo simply sends out a signal to power on and power off, then the aerials own power moves it to position

if your replacement stereo is sending the ' wrong ' signal , the aerial is probably confused, and thinks on is off and off is on , or something in between if the voltage is permanent for the signal ,



BB

 

That makes sense...? Is there a solution or is the solution a new aerial?

 

Remember that the CPU is in the middle of the operation. The radio connects to the CPU, and the CPU controls the UP and DOWN relays. You can easily measure the voltage on the antenna control wire from the radio, and check for proper control voltage from the CPU at the sockets for the two relays.

From the schematic, it appears the runtime of the antenna motor must be controlled by the CPU, because no logic circuitry is shown inside the antenna motor housing, nor have I found anything but a motor inside the housing on the couple of occasions on which I had to disassemble a motor to unwrap and pull out the broken end of the nylon cable gear.

Cheers,

Don

 

Thank you Don, I have my Fluke multimeter ready for some diagnosis...?

Roger

 

Depending on how modern your new headunit is Im surprised if it has an "antenna" function output. My 94 XJ6 would output to the antenna but only when AM/FM was selected so in cassette mode the antenna remained down. When I upgraded to a unit with bluetooth, and I've seen this on quite a few newer units they don't have an output, I added a 12v source to the antenna when the radio was on. I also added a switch so I could leave the antenna down unless I chose to listen to AM/FM but more importantly the antenna wouldn't try and go up if it had snowed and frozen so the motor wouldn't strip the antenna cable.

I rarely listen to the radio itself and just stream from my phone so 99% of the time its down anyway.

 

Thanks for the advice. The unit I used is an Alpine CDE 172BT, a good mid priced unit.
I've used Alpine head units in the four Jaguars I've owned. This problem is most likely
a logic problem. When I removed the original unit I had to cut the two wires (in line fuses) to the lighting logic modules
and THAT is my problem. I used them for switched power as well.
When I put the lights on the antenna stays up, when I shut 'em off it retracts
If I get the timing between turning on the tuner and turning on and off the lights the antenna remains extended.
I'd like to find another source of switched power and a way to connect the light logic controller wires...?