I think I blew my head unit...Help please

[s5pitfire 10+ year member]

This is kind of long, so I really appreciate it if you try to help me out.

The head unit is about 3 yrs old, its a pioneer 4600MP but still plays my mp3 discs fine (or did)

I had my car stereo installed about a year ago (last summer, all done professionally except what I did alone which was the head unit adapter (or just head unit) installation) and havnt really touched it since. Today I took the plastic cover that surrounds my head unit and CD case holder (2 slots) because the wiring that was connnected to the red LED that blinked when my alarm was armed was disconnected (I took the plastic cover off a few months ago to reposition it or something which tore the two apart (1 inch of blue/red coming from LED and then the rest of the wiring going to the Alarm unit), which were crappily connected with some tape)

The idiots that installed my pyhton alarm at CC made the wiring too SHORT so I had to add extra wiring so that I can take the cover off without having to separate the wire apart, which is the way they installed it (this is all for the blinking LED).

Okay so in order to rewire that, I had to take my head unit out as well, and as I was removing it out of the hole, all of my speakers would pop (includng my sub, loud and deep). Turns out 4 of the wires coming out of the wiring adapter out of a billion (1 white, 1 white w/ black stripe, 2 grey) were just cut and hanging with no heatsink or tape on them. So they touched the metal under my dash a couple times and I got the pop a few times before I finally got my head unit out.

Also turns out that the head unit was not properly grounded, the ground wire coming out of the back of it (out of the plug) was grounded to the bracket that held the head unit and CD case holder together (the two metal brackets). So I guess the head unit was grounded to ITSELF, so that when I removed it, there was NO ground.

SETUP: I have a Kicker 750 watt amp which powers my 10" Kicker solo baric L5 sub, my two [mid] 5.25" door speakers, and my two tweeters in my dash (all 4 are apart of a Kicker RS component setup). ( I drive a 2 door sports car). The two 6x9's behind my seat are still factory and plugged in, but are powered by my head unit.

Now, when I turn my key to "on" the radio sounds great. When I start my engine the speakers let out a high pitched squeal, and when I rev my engine (make the RPM's rise), the sound will raise and drop with it simultaneously. It's either alternator noise or ignition noise....

My dad owns an auto repair shop, this happened there and we ground tested the "Radio" fuse under my dash to see if it is hot when the key is off (or no key at all), and like it should be, there is nothing unless it is ON or the engine is running.

When I removed my head unit and all this popping went on, my key was OUT of the ignition (NOTHING BAD SHOULD HAVE WENT WRONG). Therefore, my amp must be hot ALL THE TIME? I looked inside my head unit when there was no key in the ignition, and there was a little red glowing light. I dont think the head unit is hot unless the key is on, though (ie. when key is ON then my head unit turns on and plays the CD)

You may ask why I didnt disconnect my neg battery cable like I should have, well, it resets my ECU which in my car isnt a good idea (ive had voltage problems before with different batteries and such when resetting it) , and also my car alarm, it would go off and I have no idea how to program it if I had to..

Either my head unit or my amp is blown? I'm not sure, my amp is grounded properly to one of the bolts that hold the rear seat down (2 door w/ insurance seats) so hopefully the amp is fine. None of the speakers are blown, they all play good when engine is off like I said.

Any suggestions I would greatly appreciate... isnt there some kind of signal canceller that I could add to the red wire? //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

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[jmanpc 5,000+ posts]

clif's notes plz?

 

[s5pitfire 10+ year member]

clif's notes plz?

Lol sorry I got carried away:

-There were a few dangling wires connected to my head unit through the [aftermarket] HU adapter

-They were just cut, not covered, so they touched metal, and the HU was UNGROUNDED/grounded improperly (oops? but I thought it wasnt supposed to be hot with no key in ignition?)

-Loud popping noises when wires made contact with metal (metal under my dash in the area where head unit goes)

-Stereo sounds perfect when key is "ON" (engine off)

-Loud, high pitch buzzing/static when engine revs (RPMs go up) and sound goes along with it, higher RPM, higher the pitch of the buz from my speakers. (goes with alternator or ignition)

-What went out? Im guessing my head unit, hopefully not my 750w amp (it was grounded)

 

[kross 10+ year member]

I think these are the key points:

1. the HU was UNGROUNDED/grounded improperly

2. Sterep sounds perfect when key is "ON" (engine off)

3. Loud, high pitch buzzing/static when engine revs

These symptoms point to a faulty ground. It's also possible you fried the ground connection inside the HU when things shorted out.

 

[s5pitfire 10+ year member]

I think these are the key points:
1. the HU was UNGROUNDED/grounded improperly

2. Sterep sounds perfect when key is "ON" (engine off)

3. Loud, high pitch buzzing/static when engine revs

These symptoms point to a faulty ground. It's also possible you fried the ground connection inside the HU when things shorted out.

thanks for the reply

i dont see why it would short it out unless the HU was hot when I did all of this. Key was out of the ignition... is something wrong here?

And I think it may have fried it because i still had the buzzing when the ground was bolted to the HU bracket itself, and then I moved it to the car itself under the dash and same noise happens

 

[kross 10+ year member]

It still has power going to it, like for memory and clock. You said "I had to take my head unit out as well, and as I was removing it out of the hole, all of my speakers would pop (includng my sub, loud and deep)."

Anyway, make sure you have a good ground on the HU. If that doesn't do it, you may have damaged something. You could also try wrapping bare wire around the RCA plugs on the back of the HU, and grounding that.

 

[s5pitfire 10+ year member]

Well I think I did damage something since it has that noise when it was on my original ground (bad ground) and also on the new one (which is good, part of the car and not the HU)

So I guess I learned that I need to have a good ground going to my HU even when i'm not using it.

The popping noise would occur when the ground wire would de-ground and ground to what the HU bracket was screwed into (part of the dash, which is a good ground). Also wiggling it out, lots of touching, then no touching of the ground.

So only when I take the HU off would there be no ground, but when it was bolted down, it was grounded. Is that where the problem is from? Ungrounding the HU period?

 

[kross 10+ year member]

Try wrapping the wire around the RCA thing. Also, you're sure your new ground is good? Not all metal behind the radio is actually grounded. You can try getting a long piece of wire, and attaching to a known good ground spot, just to make sure. Like maybe get a 15' long piece of wire, and attach it to the battery negative terminal, and to the ground on your radio.

Sorry I can't be more helpful.

-- Kevin

 

[s5pitfire 10+ year member]

thanks, i'll try that

 

[s5pitfire 10+ year member]

Im looking at the Alpine CDE-9881, and it only has 2 pre amp output voltage. Should I shoot for higher? Does it make much of a difference, 2 and 4? My Pioneer is only 2....

 

[wesl56 10+ year member]

Im looking at the Alpine CDE-9881, and it only has 2 pre amp output voltage. Should I shoot for higher? Does it make much of a difference, 2 and 4? My Pioneer is only 2....

some people say cucumbers taste better pickled //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[s5pitfire 10+ year member]

Okay how would this troubleshooter work:

Take my stock head unit and plug it into the radio plug, that wouldnt work though would it? because the speakers and the sub (of course) are wired through the amp in which the stocker cannot connect to

Or find another a/m HU and try to use that.

Probably the latter

 

[s5pitfire 10+ year member]

I have been wondering if what happened is normal.

Is the head unit supposed to be hot like that with the ignition off? I know there is a wire for memory stuff and clock but not the red 12v hot wire.... I have a feeling my HU is wired up incorrectly and I need to look up what color means what

 

[kross 10+ year member]

Doesn't sound right, but I've always disconnected the battery first, so I don't know for sure.

 

[s5pitfire 10+ year member]

Doesn't sound right, but I've always disconnected the battery first, so I don't know for sure.

Yeah that is what was going through my mind as I was doing this... just if it werent for the a/m alarm and weird ECU but now I will ALWAYS unplugg the battery

But i'm hoping someone here knows if what happened to me is normal... for the HU to be 12v hot when not even turned on