MadCoder

I'm getting no power to my head unit after putting my interior back in.

- I checked the fuse in the back of the radio and under the steering wheel and those both work. I purchased a new wiring harness on both sides since the old ones were pretty nasty.

- Used both diagrams to match up the wires and made sure they had good contact.

- I made sure the other end of the harness was secured near the fuse box.

- I tried using a multi-meter to see if power was getting through to the radio's harness but I'm not getting any numbers on it.

Any advice on how to troubleshoot would be appreciated.

Thanks,
Jon

grumblemarc

iTrader: (4)

Use an aftermarket wiring harness and DO NOT attach anything to the dimmer switch.

MadCoder

Check and check!

lostforawhile

the dimmer switch controls ground, most aftermarket radios that say dim that wire goes to positive power when the lights are on, there should be a factory wire that goes 12 volts when the parking lamps are on,it's not connected to the dimmer circuit. When the radio gets this 12 volt signal it dims itself. You need to start tracing back from your positive wire, some new radios the radio positive wire is only a signal, and the radio is actually powered from the memory wire, Clarion comes to mind, the memory circuit has a 15 amp fuse, of course it doesn't pull 15 amps when off, but that allows the radio to be turned on with the key off . If you have a radio like this,it's possible it blew the fuse for the memory circuit on the factory harness, it's not designed to handle that much current. you need to check both the wire supplying constant 12 volts and the one supplying switched 12 volts, many radios won't come on without memory power

grumblemarc

iTrader: (4)

Then you did something wrong because int e years I have used an aftermarket harness I have never had an issue.

I don't know what "I purchased a new wiring harness on both sides" means. There's only one harness and one diagram to use and NOTHING gets secured near the fusebox.

grumblemarc

iTrader: (4)

Not for an aftermarket headunit it doesn't. Especially if he's using a proper adapter.

MadCoder

A yellow wire says "12v Constant" which I'm guessing is the memory wire?
and the red wire would be 12v only when the key is in the ACC position (1 click forward)?

lostforawhile

the FACTORY dimmer switch, most of the Honda stuff is a constant 12 volts to the dash lamps and the ground changes, most aftermarket head units simply use a 12 volt positive signal from the lighting circuit to tell them to dim, the same way the factory clock knows to dim, it's not a varible dim ,it's either bright or dim,unless the headunit has some sort of adjustment, but the 12 volts from the lighting circuit is simply a signal

grumblemarc

iTrader: (4)

The headunit I installed last has NO provision for dimmer switch. I've NEVER tapped into the dimmer. Everyone posting up headunit problems on this forum always does.

This is the install I did last October.
https://honda-tech.com/forums/audio-security-video-27/96-civic-ex-m-headunit-install-no-cut-wires-2993540/

No tapping into any fuse boxes or dimmer switches.

Wire up the aftermarket harness to the headunit wires and that's it. Don't make it complicated with all this extra fluff.

grumblemarc

iTrader: (4)

What does headunit diagram say they are?

lostforawhile

yes constant, what is the amperage of the fuse on it? if it's one like I mentioned the factory harness may not be able to handle the current, ones like this are getting more and more common, the radio switches off with the key, but you have the option of switching it on without it, even if it doesn't many new ones pull most of their current from the memory circuit,with the switched circuit only being a signal, just like the turn on wire on an amp

grumblemarc

iTrader: (4)

First I've heard of this. Which units?

lostforawhile

no one said to touch the dimmer, the lighting wire in the factory harness is usually independent of the dimmer and is either on or off, if the radio has a wire to the lighting circuit, it used a switched 12 volt signal to tell the headunit to dim at night, some newer ones don't have a dim wire, they use a photocell to tell when it's dark in the car

grumblemarc

iTrader: (4)

You're just helping to confuse things. My deck doesn't have any photocell and it doesn't dim. So you cannot generalize these things.

It's this simple. EVERY time.
Match up the wires from the aftermarket harness and the new deck wires just like I did it in my walkthrough. SOMETIMES you may have to switch around the yellow and red wires but that is it.

lostforawhile

most clarion for one, I'm trying to remember which others off the top of my head, if the fuse in the radio harness is higher for the memory,then the swtched power, you've got one, my clarion has a 10 amp fuse for switched power and a 15 amp fuse for memory, even with the key off, if you push and hold the power button with the key off, the headunit will switch on

grumblemarc

iTrader: (4)

OP. What deck are we even talking about so we can stop guessing?

lostforawhile

I'm not confused I've been doing this for 20 years as a side job, most Hondas have an illumination circuit for the gauges and switches that switches on 12 volts with the parking lamps on, and a variable ground to dim, there is also a non dimming illumination circuit, it's either on or off, if a modern radio has an illumination wire thats what it goes to, if it detects 12 volts, the headunit dims itself so it doesn't blind you at night, most of the time the illumination wire in the factory radio harness is this wire. In the old days,radios actually had light bulbs that would connect to the dimmer circuit, those haven't been made in probably 30 years at least. Don't think of the illumination wire as a dimmer, that confuses things, it just tells the computer in the head unit to reduce it's brightness,thats all

MadCoder

http://www.docs.sony.com/release/CDX...tion_Guide.pdf

Says red one is for power with ignition in accessory position.
Yellow is for constant power.

After using the multi-meter the yellow has power when car is on or off. Red only has power when key is in ACC pos. or greater.

I also looked at your post about the install you did and I did it pretty much the same. I have the same harness as you in the pic.

Former User

OP, your first post only mentions voltage from the dash radio fuse which is controlled by the ignition switch. To work, your radio also needs constant voltage from the hood fuse box via the 7.5A Back Up fuse. Check whether this hood fuse is blown.

lostforawhile

I never said yours did, I said if it doesn't have an illumination wire it probably does, it was a general statement

Former User

Guys, read each others posts but talk to the OP not to each other. The arguing is derailing this thread.

grumblemarc

iTrader: (4)

You're confusing ME and I've been messing with this audio stuff as a side hobby a lot longer than that and this is what I've used as a method to installing headunits for as long as they've been making these wiring adapters. Anyone that knows what a Benzi box was will know how long that is.

Match up wires and go. Didn't have to know anything else and never had an issue keeping it this simple.

My advice to the OP is to keep it simple. If you want to know about all the extraneous stuff then do so but right now isn't the time. If you think the inner cabin wiring is the problem then walk it right over to the battery and test it.

Oh. Double check you have a good ground and for blown fuses as Ron states. I'm out to avoid further confusion.

MadCoder

I'm getting a reading from the multi-meter when set to 2000m, which I don't know if it's correct or not but would jump between ~80-120. Dont know if that help but I will test the under hood fuse next.

I have a small fuse tester that came in a kit and I've been testing them this way. I also tested a visibly broken fuse to verify it worked in both scenarios.

lostforawhile

OP check the rating on the fuse in the radio harness circuit if it's bigger then the fuse for the constant power circuit in the car, that fuse ifs probably blown, if it is you simply need a source of constant voltage that is rated for what the radio needs, no one mentioned grounds, have you checked your ground wire?

MadCoder

What's the correct way to check the ground wire on a multi-meter?

Also, I installed an after market stereo in my nieces 94 Intergra and it had the exact same wiring harness and I installed it the exact same way. Matched up the wire colors, double-checked with the diagrams, and everything worked, even the power antenna.

I think I either knocked something loose or messed something up when I was replacing the interior but it might also be that the radios dead now. It's been sitting in my garage outta the car for like 4 months now.