install new headunit in car - fail

[vanaxel]

Hi,

am trying to install a new HU in the car but cant seem to get it to work. During the installation process, the cables shorted and blew the fuse, so replaced the faulty fuse and all looks ok on the fuse end.

However when I connect the HU, it powers on for 2 seconds and goes off (the antenna goes up and down during this time as well). When i turn the key to ACC or ON, nothing happens. It seems that there is no power flowing from the ignition source to the HU?? any ideas what might causing it.

any help would be greatly appreciated!

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[bbeljefe]

Did you check/replace the vehicle's fuse for the circuit you shorted or did you only change the fuse at the head unit?

 

[robert420 10+ year member]

check the vehicle's fuse. if its not that just try touching the positive and negative directly to the cars battery. if it doesnt work then, you couldve fried it...

 

[nvturbo 10+ year member]

More than likely the fuse that powers the headunit is burnt as well. Check and replace it.

 

[vanaxel]

Hi guys,

I replaced the 7.5 amp fuse for the radio found below the steering column. There was another 15amp fuse for stereo which was fine.

 

[cfox10 10+ year member]

Why do you have the bat hooked up when installing? I take my harness and kit and wire outside the vehicle then it's plug and play. Op... Id be interested to see how you have it wired. Check it in a constant 12v source before searching for fuses.

 

[vanaxel]

Why do you have the bat hooked up when installing? I take my harness and kit and wire outside the vehicle then it's plug and play. Op... Id be interested to see how you have it wired. Check it in a constant 12v source before searching for fuses.

That was a mistake not to disconnect the neg, but , then isnt that what the fuses are for to protect the circuit against short?

I just twisted the wires together and electrical tape it for now and will heat shrink after it confirmed working correctly. One of the wires touch another which was why the shorted initially.

How would I check on constant 12v source? Sorry am newbie here trying to learn.

 

[Side Show 10+ year member]

use a small test light/probe thingo to find ur constant pwr

 

[Side Show 10+ year member]

i'd say u have the constant and aCCESSORIES round the wrong way

 

[jrdnhsnbrg 10+ year member]

I've found it easiest to do all the wiring at a table inside with good lighting. I'm lazy and always just twist the 2 corresponding wires together then electrical tape over them, then electrical tape over all the connections in one big bundle so all the wires stick together.

 

[vanaxel]

i'd say u have the constant and aCCESSORIES round the wrong way

Thanks. am halfway there. Now the stereo powers up and when the key is switched in ACC or car starts but it goes off after a couple of seconds. Am pretty sure the wires are twisted to nice and tight and held in with electrical tape.

Could it be some of the wires are paired wrong? The previous owner might have used another unit and replaced with the stock unit when selling and might have did a dodgy...hmmmm...

the only others i have wired are antenna and earth and the rest are for the speakers (neg and positive)

IS there any way to check using a DMM?

 

[cfox10 10+ year member]

Thanks. am halfway there. Now the stereo powers up and when the key is switched in ACC or car starts but it goes off after a couple of seconds. Am pretty sure the wires are twisted to nice and tight and held in with electrical tape.
Could it be some of the wires are paired wrong? The previous owner might have used another unit and replaced with the stock unit when selling and might have did a dodgy...hmmmm...

the only others i have wired are antenna and earth and the rest are for the speakers (neg and positive)

IS there any way to check using a DMM?

Sounds like a bad ground. Watch the voltage with the dmm on the accessory and 12+ when it's on and see what happens to it when the radio shuts off. Try grounding somewhere else.

 

[JamesBondo]

Am pretty sure the wires are twisted to nice and tight and held in with electrical tape.

Solder them if you can.

As cfox10 said, see if you keep a steady 12v on the acc wire. If you do, the head unit may be bad.

 

[CrossoverOre 10+ year member]

does the clock reset after it shuts down and you turn it on again? Is the antennae plugged into the deck? Most decks will pull a sufficient ground from the ant, not the proper way but it typically enough to at least power it on. if your messing around with the wiring anyway try this. Connect both acc and constant wires from the deck harness to the vehicle 12v constant and see if the deck operates like it should.

 

[robert420 10+ year member]

does the clock reset after it shuts down and you turn it on again? Is the antennae plugged into the deck? Most decks will pull a sufficient ground from the ant, not the proper way but it typically enough to at least power it on. if your messing around with the wiring anyway try this. Connect both acc and constant wires from the deck harness to the vehicle 12v constant and see if the deck operates like it should.

i already mentioned that, only connecting it to the battery...