I've got an Alpine IDA-X001 head unit that I just installed. It looks great and I'm happy with it. It has a "dimming" feature that I would like to hook up, but instead of hooking it up to the lights, I would like to hook it up to a switch so that I can "enable" or "disable" it as I please. What I was going to do was connect the "dimmer" wire from the head unit to a (single pole?) on / off switch, and then connect that switch to an accessory such as the cigarette lighter under the radio. Am I correct to figure that would then let me turn the dimming feature on / off manually? Are there any problems with this idea that I'm not considering?

(The instructions say to connect the dimmer wire to the instrument cluster illumination lead, but I don't want to do that for 2 reasons, first I drive with my lights on in the daytime and I'm afraid that it will be to dim for daytime viewing, and secondly I'm looking for what would be easiest, and keeping all the wiring right under the head unit seems pretty easy.)

Duck - To do what you want would take a single-pole switch as you guessed. BUT, I don't think it will do what you think it will. The wire you're discussing is meant to go the instrument cluster so that when the headlights are on (there's power to the wire) it will use that to power the display. Turning the brightness of the dash lights up/down with the dimmer will then also make the display on the H/U brighter or dimmer.

So, doing what you suggest would then either have full power to the wire or it wouldn't. In either case, the display would be at full brightness since if the switch is "off", with no power to the wire, then the H/U would assume the headlights are NOT on and use full power for a brighter display during the daytime. If you turned the switch "on", it would still have full power from the power socket, the H/U would assume you have your headlights on and you would be providing full power to the display giving you a nice bright display. So in either case, the H/U would have full power to the display.

So, if you use your headlights during the day, why not hook it up as the manual suggests, running the wire to the instrument cluster, and then just turn the dimmer switch for the dash on high? That way you'd still have the option of toning it down at night, just as you do with the dash lights?

The only other alternative that I can see would be to use a potentiometer (another dimmer switch) instead of the single-pole you suggested, but still connected to the power socket. That would give you control over the brightness of the display, but it would be separate from the dash lights.

Thoughts?

-Gonzo

Gonzo,

First off - thanks for the reply - there's tons of information & knowledge on here and I appreciate the input.

From what I can tell the head unit does not dim "variably" with the instrument cluster. There is a "preset" dim level that the HU dims to if the lights are turned on. I do know that HU does not draw power from this wire to power the face of the HU...(I know that because at the moment, the HU is hooked up with the "dim" wire just hanging behind it disconnected, and everything works fine...except obviously the dimming function). That is how I came to the conclusion that the HU is simply using the "dim" wire to detect if the lights are on and then flipping over to it's preset "dim" level.

Does that make sense?

Thanks.

Steve

Duck - that should work fine.
That lead is usually orange if I recall right, and if +12V is present, the HU just dims itself. Pretty standard for all HU's.

One of those Yes/No things: If +12V, the HU dims. If no power, HU at full illumination.
Actually it might be the other way around, but it's kinda irrelevant - just don't label the switch until you know for sure whether Open=Bright or Open=Dim.

Variable dimming would be completely different, but you seem to be talking about the On/Off dimmer functionality from what I can tell.

EDIT - just dug up an old link to some Nissan wiring diagrams. Now it all comes back to me:
There are two different leads for lighting in the harness.
Illumination: Variably dims with dash lights
Illumination Control: 2 stage dimming based on headlights on/off

Pretty sure they are both variations of Orange (one with black, one with white)

Here's the link:

http://www.velocitymotorsport.com/install_notes/nissan.htm

I think our stock HU's are diagram 2.

05 - thanks. And you're right, I'm not talking about the variable dimming, just the all or nothing. I'm going to get a switch over the weekend and give it a try. I'll let you know how it goes.

Thanks.