# Car stereo installation help. No power to new head unit, no power to old stock unit



## psteng19 (May 4, 2002)

I've done car stereo installs before. This is my third one.
Car is a '96 Sentra. Replacing the stock unit with an old Pioneer DEH-P7200.

I hooked up the wiring harness to the Pioneer harness, pretty standard procedure. All wires match up except for the unnecessary ones (illumination, dimmer, power antenna, amp, phone/mute).
I turn the car to ACC, no power. Nothing. Not even a display.
I turn the car on, I get dash lights, test blinkers, wipers, etc. All work fine.

Strange. I unplugged everything and hooked the stock unit back up and nothing. Not even the time on the cheesy LCD.

Next thing I checked was the fuse box. The fuse looked fine, but just in case, I swapped it with the spare ones. Still testing with the stock unit and I still get nothing.

I must mention that when I did the installation, I did not unplug the negative terminal on the battery.
If that destroyed something, what must be done to fix it?


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## Punkrocka436 (Jul 8, 2003)

did you check the under hood fuse box as well?


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## psteng19 (May 4, 2002)

Punkrocka436 said:


> did you check the under hood fuse box as well?


I looked but I didn't see anything indicating the stereo in there.
Do you know where I should be looking?


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## Punkrocka436 (Jul 8, 2003)

it doesnt matter if its a stereo fuse or not....if you short a wire to ground, any of the fuses could blow....look at ALL of your fuses to see if something is blown

otherwise i would say you dont have a good connection


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## Twiz (Aug 24, 2004)

Did you install this new unit in your dash and ground it to an actual ground or you were just holding it in your hand while you were testing it to see if it works ? You'll need a voltage tester here and trace the wires back to the fuse panel... check the dome lights or room lamp fuse also.


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## Ninety-Nine SE-L (May 5, 2002)

seriously, get a voltage tester, it'll narrow things down easily.


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## roneto (Dec 9, 2003)

*one word*

test ligt you can get a cheap one in any auto part store. then go thru all the power wires of your radio before and after the area that you made the wire connections so you know if you get power behinde the area were you cut the wires the problems is your connections were you tapped in for the new radio.
make sure you check all the wires with the car turned off and on.
and make sure you have the constant power wire and the reg 12volt wires connected right because some time you can connect them backwards. and just incase you are using another ground other than the factory wiring ground make sure it is a good one
test light if you have the car off and you check the wires and you get power the test light will go on thats is the constant power wire. when the car ign is turned over you should have two power wire and the test light will go on on two diffrent wires. i hope this helps you good luck.


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## jamoroso8 (Oct 18, 2004)

when you hooked it up did you have the antenna plugged in? i know the stock radio won't work if you don't have it hooked up. hope this helps.


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## Ninety-Nine SE-L (May 5, 2002)

For the stock radio, the antenna provides some of the grounding, however, actually having the head unit mounted correctly will ground it just fine.

for aftermarket radios, you have to ground the negative wire yourself. This could be the problem. Aftermarket HU's have a negative wire, but surprise, there's nothing in the stock wiring harness to hook up the negative wire. Solution: crimp on a ring terminal and bolt the wire down to some metal surface.


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## psteng19 (May 4, 2002)

Ninety-Nine SE-L said:


> For the stock radio, the antenna provides some of the grounding, however, actually having the head unit mounted correctly will ground it just fine.
> 
> for aftermarket radios, you have to ground the negative wire yourself. This could be the problem. Aftermarket HU's have a negative wire, but surprise, there's nothing in the stock wiring harness to hook up the negative wire. Solution: crimp on a ring terminal and bolt the wire down to some metal surface.


The stock antenna is plugged in during testing.

Here's a bit of info I neglected to mention.
While doing the install, I was messing with one of the speaker cables in the in the truck (rear right speaker - aftermarket Kenwood).
I pulled off the positive lead so that I could use pliers to squeeze it tighter, but while pulling it off, it brushed on the frame and sparked.
I'm thinking this must've blown a fuse.


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## thecrippler_1989 (Oct 24, 2006)

*Help*

If you find out what is wrong let me know cause I am having the same problem.


psteng19 said:


> The stock antenna is plugged in during testing.
> 
> Here's a bit of info I neglected to mention.
> While doing the install, I was messing with one of the speaker cables in the in the truck (rear right speaker - aftermarket Kenwood).
> ...


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## psteng19 (May 4, 2002)

Wow, talk about blast from the past.

BTW, it was the ground.


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## thecrippler_1989 (Oct 24, 2006)

How did you get the stock radio to work?


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## UNISH25 (Aug 12, 2002)

psteng19 said:


> I've done car stereo installs before. This is my third one.
> Car is a '96 Sentra. Replacing the stock unit with an old Pioneer DEH-P7200.
> 
> I hooked up the wiring harness to the Pioneer harness, pretty standard procedure. All wires match up except for the unnecessary ones (illumination, dimmer, power antenna, amp, phone/mute).
> ...


There are only two possible things:

1.) That red wire is not connectoed to the battery properly.
2.) The head unit is completely bad.


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