Nick Posted March 3, 2005 Share Posted March 3, 2005 I'm wiring up my boost gauge this weekend and I need a place under the driver's dash to tap for power, but I'd like the gauge lighting to be able to dim like the dash lights do with the dimmer switch. In my VW, I just tapped into the power wire coming from the dimmer switch, but I have a feeling in the Leg it's not quite that easy. Before I go cutting wires, are there any electrical gurus in here? -Nick Link to comment Share on other sites More sharing options...
blue_obxt Posted March 3, 2005 Share Posted March 3, 2005 You should be aware that there are two different illumination wires going into the headunit. This is so that the red and white lighting can be controlled separately. Link to comment Share on other sites More sharing options...
Nick Posted March 3, 2005 Author Share Posted March 3, 2005 You say there are two illumination wires going to the headunit...do you actually mean the instrument cluster? Link to comment Share on other sites More sharing options...
blue_obxt Posted March 3, 2005 Share Posted March 3, 2005 No, I do mean the headunit. I just finished an amplifier install, so I had to mess with the wiring harness for the headunit. The dimmer should control some of the lighting on the headunit. But I imagine that the instrument cluster would have two wires as well, because it also lights up red and white. You've probably noticed that the guages are always lit up white, but when you turn your headlights on they dim, and the rest of the dash lights up red. Link to comment Share on other sites More sharing options...
Nick Posted March 3, 2005 Author Share Posted March 3, 2005 You don't happen to remember which wire is which, eh? Link to comment Share on other sites More sharing options...
rao Posted March 3, 2005 Share Posted March 3, 2005 Look at the wiring diagram for the radio plug for any 2002+ Subaru, they are all the same. One is pin 7, the other one is pin 1. http://www.ravensblade-impreza.com/modifications/misc/wiring/radiowrx.html Pin 14 is now used - it is the power for the antenna amp. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
blue_obxt Posted March 3, 2005 Share Posted March 3, 2005 I *think* pin 1 is the white lighting and pin 7 is the red. I have to open my dash back up on Monday night, so I can double check then. A warning about pin 14: someone (don't remember who) posted that it only gets power when you are in radio mode, so it might not be the best choice for an amp turn-on lead. I just used accessory power... Link to comment Share on other sites More sharing options...
rao Posted March 3, 2005 Share Posted March 3, 2005 That's right. I should have remembered it because I had that exact problem when I first hooked up my sub. Rob IF YOU CARE ABOUT YOUR CAR YOU SHOULD NEVER DRIVE IT Link to comment Share on other sites More sharing options...
Nick Posted March 3, 2005 Author Share Posted March 3, 2005 I have a multimeter, is there any way to check which wire is which without cutting the insulation? Link to comment Share on other sites More sharing options...
blue_obxt Posted March 3, 2005 Share Posted March 3, 2005 Yeah, you could probably figure it out. If you disconnect the wiring harness from the back of the head unit, you could touch one probe to the ground pin and the other probe to one of the illumination pins. Then I guess you could play with your dimmer switch and the "sun" switch on the trip computer and look for corresponding voltage changes. Link to comment Share on other sites More sharing options...
blue_obxt Posted March 4, 2005 Share Posted March 4, 2005 Okay, so my parts came a day early . It looks like I was right, pin 1 is white lighting and pin 7 is red. But I'm not an electrical engineer, so you may still want to investigate with the multimeter a little. Link to comment Share on other sites More sharing options...
Nick Posted March 4, 2005 Author Share Posted March 4, 2005 Well I attached my boost gauge to the car battery to check out the lighting, and the LED is dimmer than I thought, so I think I'll just be tapping for power- the dimmer function won't be needed. Thanks anyway. -Nick Link to comment Share on other sites More sharing options...
hodgeee Posted March 4, 2005 Share Posted March 4, 2005 Can't tap into dimmer switch. If you check, the door lights are pure 12 volt and do not dimm. The gauges and the stereo control lights work off of mVolts, with a 12 volt constant supply. So the 12volt runs the lights, but the dimmer sends MVolts signals to the stereo, and dash. This means that there is a control circuit in both units that controls the voltage, and the fact that they are a LED based light in both units, they probably only need Mvolts to work. They are in the .25 to .31 volt range when using the dimmer switch. Reostate is the way to go if you need to dimm. Link to comment Share on other sites More sharing options...
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