New head unit stays on after after car turns off?

DeusExMachina · Post by **DeusExMachina** » Tue Dec 07, 2004 5:54 am

Weirdest thing ever. Takes about 30-40 seconds to shut off after being on/in acc.

Suspected bad head unit ground, but this is the oddest part:

I pull the key out, the head unit continues to play music. I push in the cigarette lighter and the head unit turns off! It seems to be draining whatever power is left in the system..but I don't know why there's still power. I redid the engine grounds with 0 gauge wire, 0 gauge to the chassis and 0 gauge to the intake manifold. Still does it.

I don't get it...Vikash?

1991 Legacy Turbo

vrg3 · Post by **vrg3** » Tue Dec 07, 2004 6:08 am

I don't see how a bad ground could cause this to happen.

Is this the stock head unit?

What other modifications have you done to the car's electrical system? It kind of sounds like there's a big capacitor hooked up to the accessory circuit somewhere.

123c · Post by **123c** » Tue Dec 07, 2004 6:18 am

Some head units stay on for an extended ammount of time. I know with many GM cars, the radios will stay on until the door is opened...

DeusExMachina · Post by **DeusExMachina** » Tue Dec 07, 2004 7:32 am

Its aftermarket. Eclipse unit. I don't see how it can be a "feature" because the power is supposed to be cut when you turn the key. It does seem like a big capaciter is in there.

As far as I know, its completely stock. I just changed the grounds around to try and fix it, but no avail. Put on a aftermarket neg terminal, 0 gauge wire to chassis, 0 gauge wire to intake manifold.

Brat4by4 · Post by **Brat4by4** » Tue Dec 07, 2004 4:11 pm

Mine does this also. I just got used to it. My car has an alarm installed from before I bought it, I don't if it is that or something else. My head unit is a Panasonic.

123c · Post by **123c** » Tue Dec 07, 2004 4:59 pm

Brat4by4 wrote:Mine does this also. I just got used to it. My car has an alarm installed from before I bought it, I don't if it is that or something else. My head unit is a Panasonic.

That is what my brother has in his '94 turbo legacy, and it does the same thing...

vrg3 · Post by **vrg3** » Tue Dec 07, 2004 5:06 pm

Weird.

I guess it's possible that the head unit manufacturer put a big cap on the power supply to maek the unit work better with marginal charging systems.

If you don't have any other non-stock electrical thing on your car, I guess that has to be it.

It seems dumb not to isolate that from the rest of the accessory circuit though.

Actually, it seems dumb to put it on the accessory circuit. Wouldn't it make more sense to put it on the constant circuit?

Hmm!

Is there any chance that you hooked the "constant +12v" wire on the head unit to the car's accessory +12v supply?

DeusExMachina · Post by **DeusExMachina** » Tue Dec 07, 2004 6:35 pm

There's power connected from Acc 12v and Ignition 12v. So the head unit is on when the car is on and when the key is turned to Acc.

I also have some random alarm system in my car. I wonder what happens if I pull the brain...

Post by **Legacy777** » Tue Dec 07, 2004 6:45 pm

Have you actually put a test light/meter on the ACC & Constant leads going to the radio and verified that constant is on all the time, and the ACC lead goes off when the key is turned from the ACC position to the OFF position?

If not, there's your problem.

Brat4by4 · Post by **Brat4by4** » Tue Dec 07, 2004 6:58 pm

I see what you and Vikash are getting at, but that is simply not the case. If the wrong wires were hooked up then it would be painfully obvious when you lose your settings everytime the car is shut off and it would play continuously after you took the key out. We can just go ahead and assume that they are wired in correctly. Plus, I now have mine on the adapter harness, so it can't be something wired wrong.

The constant power source is only used to keep power to the internal memory and the remote sensor deal, I'm pretty sure. The ACC line is the one that actually powers the unit, because that is the only time it should be able to be powered on. Grounds could not be the problem, either. Where the capacitor resides seems to be what we need to find out. But I really don't care, its not broke... just different

So if there is a song that I want to hear the whole thing and not miss up to a minute of it, I just pause the song. Kinda freaks people out when I take the key out and the car does not turn off and THEN when the car shuts off the radio keeps going.

I know my alarm system has a backup battery, so I don't know if it is somehow draining that... doubt it with the voltage differences, though. Is there any known timed circuit in our cars? I will try the cigarette lighter when it does this and see if mine will cut off, too. The time the radio stays on varies also, it is not a set time period. Sometimes it doesn't do it at all and will shut right off. Other times I come back and it is over 40 seconds into the next track.

vrg3 · Post by **vrg3** » Tue Dec 07, 2004 7:40 pm

DeusExMachina wrote:I also have some random alarm system in my car.

Hey, you said your electrical system was completely stock aside from the head unit and grounds!

Think carefully about whether there are any other modifications to the electrical system that we might want to consider.

I wonder what happens if I pull the brain...

Yeah, try that... Maybe the alarm has the cap. Seems weird, but maybe.

You might be able to "fix" the problem with a simple circuit like this:

The resistor would ideally be something like 3.3 ohm 50-watt, but you could probably do okay with the 8-ohm 20-watt one Radio Shack sells. Or maybe put two of those 8-ohm ones in parallel.

The idea is that when the ignition is turned off but accessory is still on somehow, the coil of the relay is powered by the accessory line and grounds through all the ignition-switched accessories. The relay sends accessory power through the resistor, which should drain off the capacitor(s).

It'd be a ghetto band-aid, of course...

Brat4by4 wrote:I see what you and Vikash are getting at, but that is simply not the case. If the wrong wires were hooked up then it would be painfully obvious when you lose your settings everytime the car is shut off and it would play continuously after you took the key out.

Well, that would depend on the particular unit, right? Some units draw power from the constant line and just use the accessory line as a trigger; some draw power from the accessory line and use the constant line for memory backup; some units use either for power and have an internal backup battery...

I wasn't suggesting it was the reason all of you guys are seeing this; it was just something to check.

Do you also notice that the accessories turn off if you press the cigarette lighter in?

DeusExMachina · Post by **DeusExMachina** » Tue Dec 07, 2004 7:56 pm

I've only noticed the head unit turning off with the cig lighter. The cig lighter doesn't get hot enough to pop when draining the juice. And it seems to be the only thing affected besides the head unit.

Sorry, I forgot about the useless alarm system in the car. There may be a battery back up or something...I should yank it anyhow.

DeusExMachina · Post by **DeusExMachina** » Tue Dec 07, 2004 8:50 pm

I pulled the brain of the alarm system and there's nothing different.

Vikash, I'm quite sure its not the head unit because the cigarette lighter drains whatever power is being stored. Thus it wouldn't be the head unit having a capacitor.

I'm positive my wiring is correct, this is the only malady in the system.

I'm going to take a pic of the wiring above the driver's footwell, maybe someone can tell me what shouldn't be there.

vrg3 · Post by **vrg3** » Tue Dec 07, 2004 9:02 pm

DeusExMachina wrote:I pulled the brain of the alarm system and there's nothing different.

D'oh.

Vikash, I'm quite sure its not the head unit because the cigarette lighter drains whatever power is being stored. Thus it wouldn't be the head unit having a capacitor.

I don't follow your logic.

If the cap is between the accessory rail and ground, it's powering all the accessories when the car shuts off. The cigarette lighter's a heavy load so it drains the cap fast.

I think the rear defroster, windshield wipers, and power mirrors are also accessory-powered. So if you tried using one of those instead of the lighter you'd probably also see the radio shut off.

DeusExMachina · Post by **DeusExMachina** » Tue Dec 07, 2004 11:04 pm

I was thinking, the cap can't be in the head unit because the accessories are being powered. But the accessories could be drawing off that. Sorry.

Brat, what year is your car? Maybe in 1991 they put some big cap in the power system so you can roll up the windows when you pull the key or something. My mother's Lexus does this, for a limited amount of time after the car shuts off.

nzKAOSnz · Post by **nzKAOSnz** » Wed Dec 08, 2004 12:16 am

pull the harness off the radio, throw a test light between the acc line and gnd. Then see if funky stuff still happens.

I have something similair in my car - aftermarket alarm - key on acc - can still wind windows up/down until it immobolises. But straight to OFF, and nothing.

Post by **Legacy777** » Wed Dec 08, 2004 4:15 am

It's best not to assume anything.....we know what happens when you do that

Test ALL your leads separately, including ground. 10 bucks says that if you re-wire the head unit to a known good ground, ACC, & 12v constant it'll work just fine, and as expected.

It's very possible the factory wiring going to the radio is messed up. I've seen it more then once.

THAWA · Post by **THAWA** » Thu Dec 09, 2004 2:49 am

FWIW my leg just started doing this about a month or two ago. It will sometimes turn off immediately and sometimes it'll take up to 6-7 seconds, or anywhere inbetween. It's quite annoying and scary.

vrg3 · Post by **vrg3** » Thu Dec 09, 2004 2:56 am

I wonder if all the times that it shuts off quickly are the times that you have the rear defroster on.

Jr.SubaruLvr · Post by **Jr.SubaruLvr** » Thu Dec 09, 2004 3:18 am

my sony deck did the exact same thing. last week i installed a new pioneer head on my my car and it stopped doing it since. So i guess its related to the manufacture.

THAWA · Post by **THAWA** » Thu Dec 09, 2004 4:26 am

vrg - nope, this last time I didn't have the defroster on for sure and it went off as soon as I turned the key

jr - I've had this deck for more than 3 years and it just started doing it on this car.

Brat4by4 · Post by **Brat4by4** » Tue Dec 14, 2004 9:04 pm

Ok, I was fooling around with this the other day... more interesting stuff.

Part of what happens is the radio will stay on after everything else shuts off, already been covered. But when the radio is off... about the the time when the radio would cut off the face lights back up (its the Panasonic ghost face), triple beeps, and flashes "FACE" then shuts off again. This is the only situation I have seen it beep and display this "FACE" message. Its so odd.

Anywho, I went to check if the other ACC powered items would cut the radio off. Well, sorta. Instead of the cig lighter I was using the wipers. First, interesting thing... with everything off and the radio doing its "extended play" the wipers still worked. So the ACC is staying powered somehow. When I hit the wipers, they go and the face shuts down. When the wipers stop (i was hitting the single stroke) the face would... *fire back up*! Then it would go for a couple more seconds until it decided to stop. So I could hit the wipers multiple times and the radio would just power down then power back up to finish its "extended play" time. Weird.

DeusExMachina · Post by **DeusExMachina** » Tue Dec 14, 2004 9:17 pm

Mine isn't that bad. If I hit the wipers, there seems to not be enough power to turn the wipers on, it just shuts everything off and the wipers don't move.

Brat4by4 · Post by **Brat4by4** » Tue Dec 14, 2004 9:23 pm

It seems to be the radio is keeping the ACC line back fed somehow, maybe power is going through the 12v line back into the ACC circuitry in some way.

I'm guessing it is in the radio itself. I just redid all the wiring. So now disconnected grounds or touching wires possible. Must be a glitch in the power supplies inside the radio itself. Its not broke, so I don't plan on fixing it. But it will be interesting if we can figure out what's going on.

THAWA · Post by **THAWA** » Fri Dec 17, 2004 6:26 am

My speculation is a bad ignition switch.

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New head unit stays on after after car turns off?

New head unit stays on after after car turns off?