Ok I'm trying to install a headunit and my yellow 12v constant, blue remote and red ignition wires all come up as 9v and not 12v, which I need to power the headunit, can anyone help me find out whats wrong or is there something special I need to know?

THANK YOU!

 

first and most important thing to know is that you need to know what you are doing prior to starting something like this. second, did you bother to even look in the audio section of the forum? third, why did you not use a vehicle specific harness? that would make more sense than trying to figure out what wire is which

 

yep, drop what you are doing and go get a wiring harness for your car. They are around 10$ and plug right in then the wires on the harness are color coded to a stanard wire color that matches up with all head units. You just put the red wire iwth the red wire, blue with blue, etc. Very simple and you still have your factory plug on the car without a huge rats nest of wiring going on back there.

also, to check your positive voltage you need the key turned on. If you're still only getting 9v then your battery is dead or something else is wrong. With the key turned on the 12v hot and the 12v ignition wires (red and yellow) should have just below 12v on them when tested.

 

+1 on binder's comment, u must be a hu install noob. IBTL

 

^^^

What's with the bashing???... Just point the guy in the right direction or STFU!

I'm pretty sure you didn't know everything at first... Which means you were a NOOB at some point in time as well...

 

that was hardly a bashing. plus most of us actually took the time to learn about our car before doing any work on it at all. it was obvious he didn't visit this section or he would not have asked this question at all. that is why he was directed to here.

so please, if you do not have anything helpful to add besides your worthless .2 cents, then i suggest you follow your own suggestion.

 

^^ Ok... But can you answer the question GhostFace is asking?

 

The first thing I would do is measure voltage at the battery. If it is ~12vdc then you know battery voltage isn't the problem. If you read 9vdc at the battery then charge the battery and your problem will go away.

If you have proper voltage I would retest each wire directly to a solid ground (find a bare metal spot in the dash behind the radio). Chances are if you have three wires reading 9vdc when the battery voltage is at 12vdc you have a ground issue.

 

Kevin, That was my initial thought as well ("The first thing I would do is measure voltage at the battery"). But, would the car even start if he's only getting 9 volts at the battery?

I think it's an excellent idea checking the battery. If for no other reason (and he gets 12v output at the battery) that tells him if his voltage meter is reading correctly. If his meter reads 9v at the battery, and the car starts fine and everything else is OK, I would suspect a problem with the voltmeter he's using.

--Spike

 

I would be extremely surprised if the car started at 9vdc - especially with the high compression of these motors.

 

^^ Kevin, Thanks for the reply. I’m pretty sure you are right about the car not starting if the battery is only outputting 9 volts.

So… If his voltmeter reads somewhere from 11.6 to 14volts at the battery, but reads 9 volts at the power line to the H/U, you are right again (Your statement: “Chances are if you have three wires reading 9vdc when the battery voltage is at 12vdc you have a ground issue.”) If that’s the case, he’s in for a miserable task trying to find the “leak.”

Hopefully it’s just a bad voltmeter, or a voltmeter requiring recalibration.

--Spike

 

Or the wire he is using for ground isn't really a ground and is showing ~3vdc (possibly a dimmer wire or something). If you put your red probe on a +12vdc wire and your black probe on a +3vdc wire you're meter will show the potential between them: +9vdc.

 

^^ Good call! I never even thought of that.

Even with the meter touching a hot wire, and not grounding the meter correctly, you could get a bogus reading (like 6v or 9v). Since GhostFace is reporting a consistently "bad" reading (9v)... I wonder if...

--Spike