Issue with electrical draw - electric gurus, what's your guess?

[the]

Car was draining the battery if not driven for a few days.

With an ammeter, tracked the drain down to the factory Hirschmann electrical antenna that is the stock antenna on the car (and is around 20 years old now).

When the antenna is unplugged (unplug the electrical connection at the antenna), the draw goes down to zero.

Does that conclusively show that something is wrong internally with the antenna, or could there be an issue in the wiring somewere else along the line?

My guess is that it is pretty conclusive, an internal fault in the antenna motor somewhere.

But these aren't particularly cheap, and I don't want to replace it if there is some other diagnosis I can perform to confirm the problem.

Any help from the electric gurus appreciated!

[911quest]

Does the drain also go away if you unplug the radio?

[304065]

The antenna's limit switch that tells the motor to shut off when the mast is retracted has malfunctioned, causing it to try and move the antenna even though it can't.

[911pcars]

Where did you disconnect the antenna? If you disconnected at the antenna, it's probably the cause.

If you disconnected at the source, there still could be an intermittent short circuit in the wire.

Sherwood

[the]

911quest - interesting thought, no I didn't try unplugging the radio. But the radio and the antenna are on different fuses. Only when I pulled the antenna fuse did the drain go away. So with the radio fuse in place and the antenna fuse out, there was no drain. So I don't think it is the radio.

john - that's what I was thinking, too, but if that were happening, wouldn't I hear something from the antenna? I can put my ear right up to it, and can't hear anything. When I turn the car off and run back to the antenna, I can hear it turning as it is retracting, but once it is fully retracted, it sounds like it stops. It goes totally quiet. Not sure if that necessarily means anything, though.

Sherwood, I disconneted it at the antenna - there a connector around 6 inches out of the antenna.

[Al S]

There's a microswitch connected to a relay inside the Hirschmann box. If I recall correctly, the relay flip flops the motor direction on each switch activation cycle. There might even be 2 relays, but it's the same idea. The relay might be draining off some power to the motor (contacts dirty or not opening fully). You can replace the relay(s) with a generic one. Or the insulation on the power supply wire might be compromised and shorting out to the case. It's not likely the motor, since the motor should not be getting power from the relay in the first place.

Hope this makes sense...