BRATDUDE Posted October 13, 2009 Share Posted October 13, 2009 I changed the plug on the right side of the car, it is still showing a very low glow for the light, with the high beam no working at all. I have also check the ground, it seems to be ok. Does any one have a wiring diagram for the 2003 forester? Thanks Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted October 13, 2009 Share Posted October 13, 2009 Subaru uses a switched ground headlight setup. I don't have any diagrams for the forester, but hopefully someone will be able to help you out. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 13, 2009 Share Posted October 13, 2009 Tried swapping the relays? Quote Link to comment Share on other sites More sharing options...
BRATDUDE Posted October 13, 2009 Author Share Posted October 13, 2009 Can you elaberate more on what this is, the switch ground system. Quote Link to comment Share on other sites More sharing options...
OB99W Posted October 13, 2009 Share Posted October 13, 2009 [...]the high beam no working at all. [...] Does the high beam indicator on the dash light? (Its 12 volt connection is from the same circuit that powers the right-side headlight.) Quote Link to comment Share on other sites More sharing options...
BRATDUDE Posted October 13, 2009 Author Share Posted October 13, 2009 No, the light on the dash is not working either, the high beam blue light. Quote Link to comment Share on other sites More sharing options...
OB99W Posted October 13, 2009 Share Posted October 13, 2009 Check fuse #9 in the main fuse box, and try interchanging the left and right headlight relays (also in the main box). Quote Link to comment Share on other sites More sharing options...
BRATDUDE Posted October 13, 2009 Author Share Posted October 13, 2009 There are no relays in the main fuse box under the dash. Do you mean the one under the hood? Quote Link to comment Share on other sites More sharing options...
OB99W Posted October 13, 2009 Share Posted October 13, 2009 There are no relays in the main fuse box under the dash. Do you mean the one under the hood? Yes, the main fuse box is the one in the engine compartment. Quote Link to comment Share on other sites More sharing options...
valvestem Posted October 14, 2009 Share Posted October 14, 2009 I'm guessing a bad ground, indicative by just a glowing light. Check for broken or disconnected wires as well. Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted October 14, 2009 Share Posted October 14, 2009 Can you elaberate more on what this is, the switch ground system. Here is the diagram for the 90-94 Legacy. http://main.experiencetherave.com/subaru_manual_scans/FSM_Scans/Legacy_headlight_wiring_diag_(US).zip A switched ground setup means that only one power source is fed to the common pin on the headlamp, and that two separate grounds are then fed back through the switch. I think you'll understand once you see the diagram. Quote Link to comment Share on other sites More sharing options...
OB99W Posted October 14, 2009 Share Posted October 14, 2009 I'm guessing a bad ground, indicative by just a glowing light. Check for broken or disconnected wires as well. Perhaps if I explained the circuit path, it would help. Here's how the circuit works, and what happens if the right headlight fuse is out (or that side's relay doesn't complete the circuit): As Josh said (and the diagram he linked to shows), power is fed to the common point between the low and high filaments on both the left and right sides. Each side gets power through a separate relay and fuse. The ground side of the low filament for left and right headlights are wired together, and the same is true for the high filament. Imagine there's no power to the right common point, due to blown fuse, bad relay, etc. When low beams are selected, the ''free'' end of the low filaments are grounded, and the left headlight is lit. However, the current can also take a path through the left high filament, then back through the right high (since they're connected), and finally through the right low to ground. There's less of a voltage drop across high filaments (due to less resistance than lows), and the right low beam will glow dimly. If the high beams are selected, a similar current path is taken through the left low filament, right low, and then the right high. Because there are now two low and one high filament in series, the voltage drop is even greater than before, and the right side will barely light, if at all. That's why I suggested in post #7 that main box fuse #9 (the right headlight fuse) and its relay be checked. Obviously, if the fuse blew, the reason should be investigated (if it wasn't just due to a filament having bridged). It's also possible, although less likely, for there to be a wire break between #9 and the right headlight common point. Quote Link to comment Share on other sites More sharing options...
BRATDUDE Posted October 16, 2009 Author Share Posted October 16, 2009 Finally, they are both working..... I did have to replace the fuse(#9), but it was still dim, i changed the relay, no help, come to find out the bulb itself had a short in it, where i would work on the other side fine, until you shook it lightly and it would dim again, i put a new bulb in it and it works great, thanks to all who helped. Quote Link to comment Share on other sites More sharing options...
OB99W Posted October 16, 2009 Share Posted October 16, 2009 A lamp filament coming loose and bridging/shorting isn't uncommon. The fuse blowing under that condition is expected. The dim lighting on the side with the blown fuse is a consequence of how Subaru designed the headlight circuit. The moral of the story is always check fuses first -- and if blown on a lighting circuit, suspect the lamp itself before doing more extensive work. Quote Link to comment Share on other sites More sharing options...
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