katz Posted June 8, 2017 Share Posted June 8, 2017 Hi all, I have a 2012 Legacy 2.5 base sedan. The climate control & shift console LED's do not light up. I can run 5 volts to the shift console and they will light, however, so I know that the issue lies within the circuit elseware. As far as the climate control, I'm not sure how to test the lighting circuit on it. I did swap out the illumination dimmer switch, and that did not fix it. The individual led's will light up when selecting each button, but there is no backlight that is lit. Is there a way that the climate control backlight can be tested? Link to comment Share on other sites More sharing options...
katz Posted June 10, 2017 Author Share Posted June 10, 2017 Can anyone confirm that their climate control panel is indeed backlit on their 2012/similar Legacy? I am sure that it should be... Link to comment Share on other sites More sharing options...
dgoodhue Posted June 10, 2017 Share Posted June 10, 2017 Can anyone confirm that their climate control panel is indeed backlit on their 2012/similar Legacy? I am sure that it should be... The 5 position duct buttons, temperature and fan knob are backlit on my '12 premium 2.5i; Yours should be the same. Have you check all the fuses? If isn't that, I would start with wiring disagrams in service manual. Probably a good place would be start is with the light stalk circuit. Does you car have any aftermarket electronics? Link to comment Share on other sites More sharing options...
YeuEmMaiMai Posted June 11, 2017 Share Posted June 11, 2017 find the illumination wire and trace it back until you find where it does not have power. Since other things are lit as they should be, this is the reason I would work back from the climate control panel/shift indicator Link to comment Share on other sites More sharing options...
katz Posted July 3, 2017 Author Share Posted July 3, 2017 The 5 position duct buttons, temperature and fan knob are backlit on my '12 premium 2.5i; Yours should be the same. Have you check all the fuses? If isn't that, I would start with wiring diagrams in service manual. Probably a good place would be start is with the light stalk circuit. Does you car have any aftermarket electronics? The car is all stock. Fuses all good. I decided to check voltage from the illumination switch, and right off the bat, nothing makes sense with the readings. There is 12V/5V out, on a couple of wires, I understand that, as the LED's use 5V. Funny thing is, when I watch the voltage on the "hot" wires, as I rotate the switch, all the readings are "reversed" - Meaning, when the switch is rotated to minimum setting, the dash lights do go out, but then there is full voltage on several of the wires. When I rotate the switch to full on illumination, those voltages go to zero. As it stands now, the climate control, console/shift lights, and the radio buttons are not illuminating. Am I correct in assuming that the power for these come directly from the illumination dimmer switch? Is there another lighting module/other in that circuit? I did purchase a service manual from some site, it is something like 6K pages, you have to search through everything manually, and the diagrams do not show any wire colors. Does anyone have a link or diagram to assist in troubleshooting this? Here is the in the manual that I have. It shows the illumination switch, wiring, and colors too, but no voltages, etc. http://i63.tinypic.com/2z9egqv.png Link to comment Share on other sites More sharing options...
cww516 Posted July 4, 2017 Share Posted July 4, 2017 Out of curiosity, have you figured out how those page jumps work yet? Once you understand those, these schematics get a whole lot more useful, because you can actually connect the dots between pages. Specifically, I'm looking at jump "A" (above the BIU)- you're looking for that same letter on the page shown on the tail, so back on page 1 for this one. If you follow it back, you find that the power for the three things you mention comes from fuse #34 under the hood (audio and climate control are there on page 4, and the shifter is shown on page 1). Looks like power to the shifter goes through a different connector than to the other two things, so if it's not the fuse, it's likely something between the fuse and wherever those two wires part ways. As far as the dimmer switch is concerned, it doesn't appear to be directly controlling backlighting to anything, it's just sending a signal back to the BIU to tell it how bright to make the backlighting. It appears to be set up as a voltage divider, and I'm guessing you're measuring voltage at the red wire? The green wire will probably show 0V when you have the switch turned all the way down. Link to comment Share on other sites More sharing options...
katz Posted July 4, 2017 Author Share Posted July 4, 2017 I'm measuring voltage on several of the wires. The gray wire actually has 5 V constant. Yes, I understand the page jumps. I thought it an odd coincidence that several things have failed, illumination/dimmer related, and they aren't on the same circuits. I guess it isn't that odd, but it makes chasing it down much more of a needle in haystack thing. Link to comment Share on other sites More sharing options...
cww516 Posted July 5, 2017 Share Posted July 5, 2017 Hmm, I was figuring that the blue/red (I think that's what LR means) would be constant power because of how that bright switch is wired in. Then again, it's talking to the BIU rather than directly controlling the lights, so who knows. Link to comment Share on other sites More sharing options...
dgoodhue Posted July 5, 2017 Share Posted July 5, 2017 As far as the dimmer switch is concerned, it doesn't appear to be directly controlling backlighting to anything, it's just sending a signal back to the BIU to tell it how bright to make the backlighting. It appears to be set up as a voltage divider, and I'm guessing you're measuring voltage at the red wire? The green wire will probably show 0V when you have the switch turned all the way down. I agree the dimmer switch doesn't appear to be controlling backlighting and the BUI appears to be. The circuits shown in the dimmer is a potentiometer (variable resistor) which basically ends as an adjustable voltage divider to the BUI. I'm measuring voltage on several of the wires. The gray wire actually has 5 V constant. Yes, I understand the page jumps. I thought it an odd coincidence that several things have failed, illumination/dimmer related, and they aren't on the same circuits. The LED's for the illumination appear to be all on the same circuit, between V and BW wires. If I had to guess the BUI, float the BW wires normally and grounds it to turn on the illumination. I am guessing you don't have power at the V wire. I would follow where the V wire goes on the schematic. Link to comment Share on other sites More sharing options...
katz Posted July 6, 2017 Author Share Posted July 6, 2017 Finally tracked this one down! Turned out to be a wire that was cut, then taped back in the loom. Previous owner had removed the aux audio jack inside the console and did a bit of a hack job, from what I can see. After removing the radio & climate control, I started poking around the wiring/loom, I could see that it was not a factory tape job. The cut wire was one that goes to the connector at the illumination switch, I suppose it is a signal to the BIU. Also reconnected the 12 Volt aux power jack inside the console. Why do people get in here and cause problems like this in a new car??? Link to comment Share on other sites More sharing options...
GTEASER Posted July 7, 2017 Share Posted July 7, 2017 Most people are pretty stupid with wiring. Some of the sh!t I have seen on my friend's cars is cringe worthy and I get right honest with them and say "Dude, you're going to burn your car down!". It's one of my pet peeves which is why I prefer virgin cars that haven't been toyed with. I try to keep all my wiring work to a minimum and splice or terminate according to the OCD rule book. Glad you got it figured out!! I commend those who track down and fix wiring issues. GTEASER's 2012 Legacy GT - Sold GTEASER's 2009 XTeaser - Sold GTEASER's 1992 Legacy SS - Sold Link to comment Share on other sites More sharing options...
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