333,333 and Weird Electrical Issue

[axgutt]

I hit a milestone on Tuesday - 333,333 miles on my 95 Legacy L wagon. I paid $2300 for it in 2003 at "As Is Auto Sales" with 174,000 miles on it. One clutch, an alternator, a couple of wheel bearings, an exhaust hanger clip - that's pretty much been it except for maintenance (fluid changes, 3 timing belts, a water pump, pulleys, plugs, wires, tires . . . ). I like to joke that this will be my 5 year old daughter's first car. She says it's not shiny enough though.

 

Just this week I did notice something weird. When I turn it off and take the key out, the radio (aftermarket) keeps playing for almost a full second. Any ideas what this might be?

 

Adam

[Cougar]

That is pretty strange alright. If there is a seperate amplifier for the unit I could possibly see why that could happen. There could also be a large capacitive filter in the power supply that is discharging after you turn off power to it.

[OB99W]

[...]There could also be a large capacitive filter in the power supply that is discharging after you turn off power to it.

Some automotive audio systems are incorporating several Farads (not µF) of capacitance.

See http://www.sonicelectronix.com/cat_i204_5--farad.html for example.

[Fairtax4me]

Porsches do that as well. But they'll play for like 5 seconds. You can get out of the car and close the door before it turns off. I've never figured out if they're designed that way or not.

 

But I have seen several aftermarket head units play for a second or two after the ignition is switched off. Just the way they are. Unless you notice it playing for longer periods of time I'd just pass it off as normal.

[axgutt]

I think I might have figured it out. I just started using one of those AC/DC adapters that plugs into the cigarette lighter. Is it possible that it's putting some extra juice into the system after I turn the key off?

[Cougar]

If the power to the socket is hot while the ignition is OFF then I too would say you have figured it out.

[Fairtax4me]

Sounds plausible. Unplug it and see what changes.

[bheinen74]

i have seen aftermarket stereo installers use the hot from the lighter for the switched power accessory lead. Which, if you have anything connectd to it that contains a rechargeable battery, will reverse feed and thus voila.

 

Also, just reading the title of your thread, "electrical and 333,333 miles" i would guess your alternator is about done for if it hasnt been changed.