Get after market headunit to work with "bright" mode

[morbo1980]

Hi Guys,

I've got an MY07 GTB with an aftermarket Pioneer double din nav head unit. I have it wired in with the illumination signal so that when the headlights are turned on the headunit screen dims. So works as expected.
But when you change the dash illumination to the "bright" mode by rolling the dash brightness wheel all the way until it does the extra click the headunit doesn't go back to bright with the rest of the dash. This makes it very hard to drive with the lights on during the day and be able to see the nav screen.

I know that with the main illumination signal there is a separate dimmer wire that varies voltage from about 0v to 12v to handle the variable brightness of the dash lights (which I can't use for the headunit). After some more research this week (on this forum and elsewhere) I've found out that there is an extra green wire that runs into the i85 connector called Night Illumination Dimmer Cancellation (NIDC). So it looks like this is what I need to use to get Bright mode to work on the headunit.

Has anyone done this before that can give me any pointers on how to use these two signals to have dimming when the headlights are on but be able to cancel it with bright mode? I'm a bit worried about frying the BIU if it hook it up incorrectly.

Thanks,
Ben

[bigBADbenny]

Some HU's and gauges require a voltage inverter module as the Subaru dimming works by varying the pos and neg voltages.
Or something like that

[zch91]

I just utilize the timed dimming function on my HU and left the illumination cable disconnected at the HU loom. Has worked fine for the past few years, as I drive with headlights on regularly (at all times of the day)

[bigBADbenny]

Googling this:

"voltage inverter subaru illumination -generator"

will reveal what I was referring to...

[morbo1980]

I just utilize the timed dimming function on my HU and left the illumination cable disconnected at the HU loom. Has worked fine for the past few years, as I drive with headlights on regularly (at all times of the day)

My head unit doesn't have a quickly accessible dimming function so I think it would drive me mad to leave the illumination signal disconnected.

[morbo1980]

Googling this:

"voltage inverter subaru illumination -generator"

will reveal what I was referring to...

Thanks for the tip. One day when I get around to putting some gauges in I'll be able to use this but my head unit doesn't do variable dimming.

I haven't pulled out the head unit yet to test what the bright signal wire does with the different switch positions but I'm guessing if bright mode is on then it gives 12v. So maybe I need a relay that's normally closed on the illumination signal wire and use the bright signal wire as a switch to open the relay when bright mode is on (effectively cancelling the illumination on signal). Or a transistor circuit of some sort so I done hear it click. My electronics knowledge is pretty basic.

[bigBADbenny]

I had thought that inverter circuit was for switching devices between bright mode for day time, and dimmed mode for night use (in the instance when hooking the device up to the subaru wires will do the opposite).

Is that what you're trying to achieve here?

[zch91]

According to the OP the dimming function works fine with the HU, but when the bright button is pressed the HU doesn't brighten.

OP- what I meant was, is my HU it has a feature in the settings that allows you to set certain times that the headunit will automatically adjust brightness, I've got mine set at 7am and 7pm IIRC. That way you don't need to worry about hooking it in to the illumination circuit at all.

[zch91]

My advice is get in contact with a fellow by the name is SVXdc (on here and legacygt.com) he is the guru with stereo wiring and possibly other wiring, hopefully he can shed some light in your situation..

[bigBADbenny]

+1 that stat.

[morbo1980]

I was thinking about it some more tonight and trying to follow the wiring diagram. Based off how the variable illumination works I wouldn't be surpised if the bright mode wire just connects directly to ground when the bright mode position/switch is activated effectively bypassing the variable illumination circuit.

So if my theory is correct then I could possibly just connect illumination to bright mode wire (via a resister i guess to stop from blowing a fuse) and into the back of the head unit. Then if the headlights are on and bright mode is off the head unit will see 12v on the illumination input. If bright mode is on then it connects illumination to ground so the head unit sees close to 0v.

I'm sure i've got this wrong some how though. Maybe I should just buy an Arduino and program it to do exactly what I want, I could do it in software so easily.

[morbo1980]

So I pulled the headunit out today and did some investigation with a multmeter. Turns out the dimmer cancellation wire is the green wire on the main 14 pin connector which I've just confirmed by looking at this post http://forum.liberty.asn.au/viewtopic.php?f=22&t=16264&start=45#p223225. I also have a green wire on the i85 connector but this doesn't seem to do anything.

When bright mode is activated the green wire supplies 12v regardless of if the head lights are on or off. So the simple solution is to wire the illumination signal through the NC contacts on a relay and use the dimmer cancelation to switch the relay open when bright mode is activated.

I haven't tried it yet so this will be my job for tomorrow.

[mynameisdaniel]

Sounds like a lot of effort to run headlights during the day. Can't you just run the dimmer signal wire through a switch? Just as easy as switching the dash light brightness...

Or find somewhere to hide one of these
http://www.ebay.com.au/itm/130858423201

[morbo1980]

Sounds like a lot of effort to run headlights during the day. Can't you just run the dimmer signal wire through a switch? Just as easy as switching the dash light brightness...

Or find somewhere to hide one of these
http://www.ebay.com.au/itm/130858423201

I did consider just running a switch. If the relay works then it won't be any more effort than wiring a switch. And it will annoy me less. And if it works then hopefully someone else will find the info useful.

[morbo1980]

No good with the relay. When it's connected the bright mode goes off so off to research another solution.