biglittledog Posted November 27, 2007 Share Posted November 27, 2007 In the true luck and spirit of DIYer's, I've been replacing my burned out instrument illumination lamps with the radio shack ones and on the last two (seat heater illum. and heated mirror "on" indicator) when I turned on the lights nothing happens and I smell burning wiring. Ugggh! I had put the seat heater switch back in and was testing the lamp and hadn't plugged in the mirror switch yet. Now I have no instrument lighting at all and no fuses have blown. By searching here, I'm guessing that I may have blown the mysterious rheostat connected to the lighting dimmer on the stalk. Does anyone know where this is located and/or what it actually looks like on a '97 OBW? I''m trying to fix it on the one "warm" day here for the next week or so and can get a used one easily if I can identify it and pull it from a yard. Thanks for all thoughts in advance! Quote Link to comment Share on other sites More sharing options...
nipper Posted November 27, 2007 Share Posted November 27, 2007 Have you added any gauges or other lights. I have been through this, as it took two "illumination controllers" to understand why. Subarus are wired in series. If you tap into one of these lines and go to ground (like any sane man would do) you are shorting out the circuit, and the magical smoke escapes the controller. The controller is 100.00 new, 25.00 ish used. Its behind the knee panel on the driver side of the dash. nipper Quote Link to comment Share on other sites More sharing options...
biglittledog Posted November 27, 2007 Author Share Posted November 27, 2007 I haven't added anything. In fact I've removed two sets of driving lights and an aftermarket alarm system from the car to get it back to stock. The illumination lights I replaced (HVAC, cruise control, Fog lights) have all been working fine for several weeks. These were the last burned out ones. I had just plugged in the seat-heat switches but had an empty socket for the mirror heat switch. Maybe that did it, although I don't know what the path to ground would be with nothing plugged into it? What does the module look like? Thanks nipper, it seems like you're always the fastest with the most accurate info...I appreciate that very much!!! Quote Link to comment Share on other sites More sharing options...
nipper Posted November 27, 2007 Share Posted November 27, 2007 Its obvious, i think its the only relay looking module on the knee panel (the panel that unscrews under the dash to get to everything under and behind the dash). Check for shorts. I blew tow of these puppies up before i figured out what i was doing wrong. WHen did you remove the alarm system? Myalarm system is wired into that same circuit somehow, so its something to look at. nipper Quote Link to comment Share on other sites More sharing options...
biglittledog Posted November 27, 2007 Author Share Posted November 27, 2007 Its obvious, i think its the only relay looking module on the knee panel (the panel that unscrews under the dash to get to everything under and behind the dash). Check for shorts. I blew tow of these puppies up before i figured out what i was doing wrong. WHen did you remove the alarm system? Myalarm system is wired into that same circuit somehow, so its something to look at. nipper Thanks nipper, I didn't realize you meant it was on the panel itself. I will try to check for short circuit to ground before I put another module in. I removed the alarm and lights back in August so I don't think its a factor here. The illum. lights I replaced before have been fine for maybe a month also. It was a good and valid thought though... I'm going to go out and pull the controller right now and give it a sniff. Thx! Quote Link to comment Share on other sites More sharing options...
subeman90 Posted November 27, 2007 Share Posted November 27, 2007 if something happened to that controler thingy on the kick panel i think i have on in the garage. I got it by mistake once...let me know if you need it. Quote Link to comment Share on other sites More sharing options...
Cougar Posted November 27, 2007 Share Posted November 27, 2007 Subarus are wired in series. If you tap into one of these lines and go to ground (like any sane man would do) you are shorting out the circuit, and the magical smoke escapes the controller. Nipper, While I could see that the dash lights are isolated from ground I wouldn't think they would be wired in series with each other. That kind of wiring would mean all the dash lights would go out if one failed. Note: Some folks have repaired the illumination module by repairing the wiring inside it. Quote Link to comment Share on other sites More sharing options...
Skip Posted November 27, 2007 Share Posted November 27, 2007 Cougar is right as usual. These are not wired like an old string of Xmas lights. My thought, usually wrong, is that the two sides of each lamp are tied to the ill. control unit. Then using full battery voltage to one leg of the lamp, the ill. control adjusts the brightness by controlling the ground or negative side. A system like this could get it's panties in a bunch if one side was grounded or saw ground through a lamp filament. A lot of the Subaru el. systems are negative side controlled. Quote Link to comment Share on other sites More sharing options...
biglittledog Posted November 27, 2007 Author Share Posted November 27, 2007 You're right about that. One failure would cause all to go out much like the strings of Christmas lights we had when I was a kid. There must be something unusual in the circuit though, since this module is basically unprotected by the fusebox... Neg side controlled...there must be a reason although I'll never know what it is! Thx, -Steve in Colorado. Quote Link to comment Share on other sites More sharing options...
nipper Posted November 27, 2007 Share Posted November 27, 2007 Cougar is right as usual. These are not wired like an old string of Xmas lights. My thought, usually wrong, is that the two sides of each lamp are tied to the ill. control unit. Then using full battery voltage to one leg of the lamp, the ill. control adjusts the brightness by controlling the ground or negative side. A system like this could get it's panties in a bunch if one side was grounded or saw ground through a lamp filament. A lot of the Subaru el. systems are negative side controlled. Thats what i meant. The High and low feed back to the controller (pos/neg), as opposed to high - bulb- ground. Maybe i should call it an isolated sircuit instead. nipper Quote Link to comment Share on other sites More sharing options...
biglittledog Posted November 28, 2007 Author Share Posted November 28, 2007 Well I found the culprit. One of my bulbs had shorted when I put the switch back together. It was one of the seat-heat switches. The illum. light is the bottom two terminals of the 6 terminal "D" shaped switch. It reads about 23 Ohms when correct. Isolated sircuit it is! I'll try and pick up a new illumination control module tomorrow and plug it in. Big Thanks for all the help and ideas. Quote Link to comment Share on other sites More sharing options...
nipper Posted November 28, 2007 Share Posted November 28, 2007 YAY you didnt do like i did, and proceed to blow up two of those suckers. nipper Quote Link to comment Share on other sites More sharing options...
biglittledog Posted November 28, 2007 Author Share Posted November 28, 2007 YAY you didnt do like i did, and proceed to blow up two of those suckers. nipper Big THANKS to you, nipper. If you hadn't warned me, I'd have blown up three of 'em. Instead I was actually methodical about it and checked all the bulbs that were added. Plus, I actually learned something in the process which makes me happy. Quote Link to comment Share on other sites More sharing options...
subaru360 Posted November 28, 2007 Share Posted November 28, 2007 Don't feel bad, my neighbor blew up one of these putting in an aftermarket radio. I sold him one off a parts car. Quote Link to comment Share on other sites More sharing options...
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