head unit install gone horribly, horribly wrong.

[freeturkeys]

ok folks, i'm ready to cry :cry: i bought a head unit for my 97 civic... its one of those alpine ones i dont recall the model number at the moment... i made the harness, plugged it in, and much to my dismay i got absolutely no power. :( i checked all the power related cables with a multimeter and the only confusing thing to me is that the yellow wire, supposedly a 12v constant is reading 4v so idk. my dad tells me that the deck should still turn on so im gonna return it but if anyone has any insight on this 4v situation just tell me.

[steve98ex]

4v? hmm thats sounds like the power wire for dash lights

to see if the deck works just hook up both power wires of the deck to the batter + terminal and the negative to the other side, this should turn it on, if it doesn't, you're deck is broke

[steve98ex]

maybe this will help you

http://www.the12volt.com/request/2000civic.asp

[freeturkeys]

ok back from the lab... tested the deck and it def works and if i wire both ignition and constant to the ignition wire on the harness the deck works (albeit with loss of memory of course) and the genious at circuit city thinks that the radio fuse in my car "is half blown and that's why it's only putting out 4v" i've never heard of a fuse that still lets power through after its blown so idk what do you guys think? oh and its definately the right wire i checked that too. thanks.

[modsHXcivi]

most the time the radio harness wires are marked ......12v ...ground ....constant power...ect. did you buy the install kit with the harness....if so just match up the wires and plug it in....check all fuses.....as for a fuse letting half power is BS never heard that one before

[makku]

maybe you've got a short in there somewhere and accidently made a voltage divider circuit :)

(take two resistors in series and T-off that wire in between the two resistors... that line will have a voltage lower than the voltage going through the main line)

[jlacoy82]

maybe you've got a short in there somewhere and accidently made a voltage divider circuit :)

(take two resistors in series and T-off that wire in between the two resistors... that line will have a voltage lower than the voltage going through the main line)

Can you vary the voltage based on the value of resistor you use? ;) That would truly be cool.

Yeah, did you lop off the old OEM harness and hardwire to that, or did you get an adapter harness for the install?

[ryan89crx]

reroute your yellow wire to a different all-time power source. also check to see if yourground wire is connected to a solid ground. ive made that mistake before and it really frustrated me...only to find out it was something simple

[makku]

Can you vary the voltage based on the value of resistor you use? ;) That would truly be cool.


of course... a potentiometer is exactly that. It's a big resistor with terminals on either end and one extra terminal that is connected to the wiper that can moved with the knob. Run 5V and ground on the end terminals... then hookup a voltmeter to the middle terminal and ground. You'll see the voltage change as you turn the knob.

These are what old school volume knobs are made of...

[Fooshitinkinjssomethingorother]

of course... a potentiometer is exactly that. It's a big resistor with terminals on either end and one extra terminal that is connected to the wiper that can moved with the knob. Run 5V and ground on the end terminals... then hookup a voltmeter to the middle terminal and ground. You'll see the voltage change as you turn the knob.

These are what old school volume knobs are made of...

Hehe, it's always fun going to radio shack asking for pots :lol:

Speaking of which, do they make them past 1 megaohm? I need it for my blinkers.

[makku]

yeah, i got a package of assorted ones and there's a 5M pot in there...

[Speed_Cult]

Ok so after a small RadioShack jones (need AWD for my X-Mod anyways :) ) and watching FooShniks sig I wondered, why not just wire up the head by-passing the harness? In other words, run his own speaker wire (factory is pretty thin) and his own power/ground. Also, FreeTurks, did you twist the red and yellow together and check the unit off the battery (red/yellow+ // black-)???

[MLD211]

I would say check both sides of all your fuses while there still pluged in with the multi meter (via the small metal pieces on the top of each fuse) and make sure if one side is reading 12 volts the other side is as well. Make sure you check all the fuses under the hood too. I have even had fuses for the radio wraped in a yellow protector so they appear to be for the air bag but there not. Anyway if that doesnt work just tap into the 12v wire on your ignition harness and run it up behind the deck. You should probably fuse the wire where you tap in. If you dont have a fuse holder two female spade connectors (the ones like you use for speaker terminals) with a standard fuse will work fine just tape it up. If you go all the way to the battery some times youll get alternator whine. As far as the 4v thing some time voltage can back feed through another circuit and cause you to see some voltage but i have delt with this problem a thousand times and 99% of the time its a fuse. But when all else fails grab the power from the ignition harness.

[JCivicB4]

My buddy has an Alpine deck that requires a constant power supply from the battery in addition to the harness... what model deck is it?

[builthatch]

ok folks, i'm ready to cry :cry: i bought a head unit for my 97 civic... its one of those alpine ones i dont recall the model number at the moment... i made the harness, plugged it in, and much to my dismay i got absolutely no power. :( i checked all the power related cables with a multimeter and the only confusing thing to me is that the yellow wire, supposedly a 12v constant is reading 4v so idk. my dad tells me that the deck should still turn on so im gonna return it but if anyone has any insight on this 4v situation just tell me.Make sure your stock radio works at this point. If not, then there is a fuse issue. easy fix. If it does work, buy a Metra harness adapter for your model car, merge the harness with your radio's harness (color coded so it should be super easy) and you are done. I choose to run heavy gauge speaker wire for my speakers directly from the speaker outs of the radio's harness to the speakers.