RedimprezaOB Posted October 18, 2015 Share Posted October 18, 2015 I'm trying to run down an odd electrical issue on my 2004, impreza ob. This popped up several weeks back just before vacation so removing a fuse to keep the battery from draining has been the solution until I had time to look at it. (Searched past discussions but didn't locate this issue) Symptom: The LCD 'backlight/illumination' never turns off on the OEM (never touched) radio. Pulling the radio fuse (fuse 9 under the dash I think) does not turn it off. Removing the Illumination fuse (12 under the dash as I recall) does not shut it off. In fact, I removal of any single fuse under the dash had no effect. I have to remove the "interior illumination' fuse under the hood to shut it off. Also the glove box light does not come on - bulb tested and good. I'll test the glove box switch short.....ly. Schematics don't show but recalling how the LCD backlight performed prior to this issue I would assume it is powered by the interior illumination circuit and the issue may be internal to the radio so a replacement may be the fix. But that doesn't explain the glove box issue which occurred at the same time. I'd hate to throw down on a replacement stereo and still have the problem..... Any thoughts, similar experience, better schematics? The shop cat has been no help on this one choosing to nap on the manual instead of providing any real insight. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 18, 2015 Share Posted October 18, 2015 On older models the glove box light only works when the key is On and the headlamps/park lamps are turned on. Kinda goofy design, yours may be the same. There may be a short to ground in the illumination ciruit, or the illumination control module may be damaged. I would recommend removing the radio. There may be a separate 2 pin plug for the illumination on the back. If there is, unplug it and see if the problem goes away. Quote Link to comment Share on other sites More sharing options...
RedimprezaOB Posted October 18, 2015 Author Share Posted October 18, 2015 Thanks for that insight. The glove box was the only thing that really was causing me (and the cat) to think something outside the radio might be amiss. However, with key on / lights on it works. The actual radio illumination lights work as they should with the light and dimmer circuit. Just the LDC backlight that never turns off. Thanks again. Quote Link to comment Share on other sites More sharing options...
lmdew Posted October 18, 2015 Share Posted October 18, 2015 Yep, Load Ground Power. The three items in any circuit. What is providing the ground? What work was done just before this started happening? Subaru or aftermarket radio? Good Luck, Larry Quote Link to comment Share on other sites More sharing options...
Bushwick Posted October 20, 2015 Share Posted October 20, 2015 Radios typically have 2-3 12v signals. One is a constant 12v+ (memory settings), one is switched 12v+ (key on radio on). Then newer radios (like last 25 years roughly) have an illumination 12v+ that's tied into the dash illumination so it matches what the rest of the clusters are doing. You need to find that 12v+ illumination feeding the radio and figure out if it's actually supplying 12v+ to the wire or not with engine off. If you'd just bought the car, I'd say someone probably swapped wires by accident and wired a constant hot instead. But since you've had the car awhile, it's either the illumination 12v+ circuit or something is shorted in either the radio or the illumination circuit. What's odd though is your dash lights should be doing the same thing, but maybe Subaru wired it exclusively separate? A quick work around would be to cut the the illumination wire (leave some excess hanging so you have wire to work with) and electrical tape the factory-side wire up so it won't short on anything. From here, you can either "live" with the loss of the back light OR splice into a key-on 12v+ source and wire that to your illumination wire off the radio. You'll loose the ability to dim it if it has the ability to dim (unless you want to wire in a dimming circuit) but it'l at least light up when the car starts (key-on). Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted October 20, 2015 Share Posted October 20, 2015 guess there isn't a CD stuck in it. Quote Link to comment Share on other sites More sharing options...
RedimprezaOB Posted October 22, 2015 Author Share Posted October 22, 2015 Funny the question about the CD! When I was working on it in the garage (nice and quite) and connected the power again I heard the CD cycle. I thought to myself, this better not be the case. But, it wasn't. Whew!! Don't get me wrong, it would have been nice to have resolved at that point. So, yes. Pulled the radio and then removed the illumination pin from the circuit and reassembled. No, current draw. I'm concluding that the issue is in the radio head itself. Now, to find something nobody will want to break into it for when I leave it and am out on bike.... or as suggested maybe I don't need a backlight tuner screen most of the time Thanks for the ideas. This car has been an absolute electrical pill pretty much since 30k miles. Guess we need something to challenge us! Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 22, 2015 Share Posted October 22, 2015 could you just make that wire switch via a relay - so that it's only "connected" when the engine is running or key is turned on? Quote Link to comment Share on other sites More sharing options...
RedimprezaOB Posted October 22, 2015 Author Share Posted October 22, 2015 See where our minds go?! I was just thinking of that and looking at where I would add (the connections) a transistor that would accomplish the task. Hand free and thoughtless operation. Quote Link to comment Share on other sites More sharing options...
Bushwick Posted October 22, 2015 Share Posted October 22, 2015 (edited) ^ I mentioned that further up. All you need is to wire one of the key-on 12v+ sources to it and it *should* go out with key-off. Can either use the radio's own key-on 12v+ source or splice into the cig lighter which should need the key on to work. Older cars (cars in general) w/o the radio illumination circuit getting a newer radio with LCD backlighting this is the only option unless you want dig into the cluster and wire off the circuit OR dig into the switch (for dimming). I use the cig lighter for driver heated seat that was retrofitted into the base seat from a 98' Outback and think the illumination light for the aftermarket oil gauge is connected to the cig lighter. Key-on, everything works. Key-off, it's off. Not entirely sure what's up with yours if it's going out with illumination wire cut and you are saying there's no 12v+ at the illumination. Could be something as simple as a heavily worn ignition switch that's NOT shutting off the circuit completely and during your messing around it coincidentally shut off this time. Basically it might be letting you remove the key while it's not completely in the locked "off" position. Or it might be sticking internally, etc. I'd connect a voltmeter or test light to the illumination circuit radio wire (radio not connected to it) and try working the key on/off a a bunch of times and see if it's possible to remove the key w/o being fully locked, and watch that test light/meter to see if you can get the key out while still having a 12v source. If it doesn't repeat, reconnect the illumination wire and attach the test light there and try the key on/off again while also trying to pull the key out w/o going fully locked off. Edited October 22, 2015 by Bushwick Quote Link to comment Share on other sites More sharing options...
RedimprezaOB Posted October 23, 2015 Author Share Posted October 23, 2015 Well, had some time to think about it a little more and do some testing the meter as well. Meter shows the illumination circuit is of (0 V) when the key is, and wiggled a bit. It only comes on when the key is in run position and lights are on. All other dash lights operate normally. Interestingly, radio properly plugged in or disconnected, when key is in the run position with the lights on, the clock looks normal. Flip on the parking lights at this point and the clock gets "flashy" - perhaps like a fluorescent having a problem turning on might be a good description. So, disconnection of the radio just eliminates the drain through the LCD. There is still some issue. This one might be beyond me. Wouldn't think it would be the illumination module as the other dash lights operate properly. I don't have a great schematic but many of the dash lights appear to be on the same circuit. Better sit down with the shop cat discuss this over libations..... Quote Link to comment Share on other sites More sharing options...
Bushwick Posted October 23, 2015 Share Posted October 23, 2015 I'm wondering if it's the actual CD player acting up. If you heard it cycling before w/o a disc in it, maybe something is sticking? Have you tried playing a CD recently? I'm not a fan of OEM radios as they rarely have proper sound quality and are lucky to output 4 watts RMS to each speaker, and despite being made in the millions, always seem to be less durable than a modern $100 aftermarket radio. For what it'd cost you to have a mechanic (who won't be trained to fix it and will suggest replacing) spend a couple hours looking at it, you can get an aftermarket Pioneer, Kenwood, etc. with adapter and trim cover for the same price or less. The bonus is you'll have more features and a better sounding unit, though you'd want to externally amp it to the doors if sound quality was a priority. Quote Link to comment Share on other sites More sharing options...
RedimprezaOB Posted October 24, 2015 Author Share Posted October 24, 2015 Yes. I waffle on the fence by the hour. It's the radio head. It's something else. Seems to now have gone intermittent so I'll work with it a bit more and report back if I find anything new and of course the outcome. Thanks for the ideas so far. Quote Link to comment Share on other sites More sharing options...
RedimprezaOB Posted October 30, 2015 Author Share Posted October 30, 2015 Ok. After way too much fooling around with this.........i.e., hooking up monitoring lEDs on circuits and then eliminating each circuit yada, yada, yada. Dang. So, the switched and dimmable illumination circuit comes in on a violet wire. Works great no issues. Just because the LCD backlight is a 'light', the circuit was in question. Removed that circuit / wire from the plug at the radio and still had the problem. Over time removed all wires except for the constant 12v supply for the memory (think mine was a Blue w/ Red stripe) and the ground wire. Turns out the constant 12v supply comes in from a circuit off the Interior Illumination circuit. Thus, when the Interior illumination fuse is removed under the hood the LCD backlight turned off. Long story short, issue is internal to the radio itself. Good grief. All that to know the issue was the radio! Quote Link to comment Share on other sites More sharing options...
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