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90 Legacy Dash lights stay on with no fuse + other electrical weirdness


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Okay, this is a bit weird. My cas is a 90 Subaru Legacy, AT, 2WD, 210k with recent timing belt and computer. The other day I noticed that the dash lights were all a little dim - I attempted to adjust the dimmer but it was up. I also noticed that both the "Manual" and "Power" lights were dim as well - to my recolection these don't dim with the rest of the dash. A few minutes later it was back to normal - around the same time, but not ecactly the same time, I turned off the heat, but that is probably a coincidence. I noticed more intermitent dimming yesterday morning.

 

So last night we went out to karaoke. Five hours later we are about to leave, and find that the battery has died. The doors seemed to be shut, the lights were all off, so I suspected a short of some sort since this battery is less than a year old and hasn't been run out yet. In the morning we jumped it and I drove home.

 

I hooked up my trusty multimeter and found that with everything off, the system was drawing about .15 amp. Seems to me, that this isn't enough to kill the battery in a few hours, but just to see, I started pulling fuses to see where it was coming from.

 

Now, when I was working in the fuse box, I left the door open, leaving the overhead and fuse box lights on. Radio was pulling a tiny amount - but when I pulled the "Illum" fuse, the whole thing went away. But, I guess there's something wrong with my methods, because when I pulled the fuse it blew a fuse in my multimeter. I switched to the 20A range (different fuse).

 

Here's the weird part - when I re-connected the battery cable directly, the lights came back on, but when I pulled the fuse again, THEY STAYED ON. As though I hadn't pulled the fuse at all.

 

So, do I have a bad fuse panel? Maybe that's where my short is? Have I overlooked something?

 

Thanks for the input.

 

JT

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Weirdness like this is usually from a bad ground somewhere. Recheck any work done recently. When the ground goes away and a circuit is powered it will follow the next path of least resistance that had a common ground. Light bulbs are low resistance until they heat up which is why they are dim. This is a simplified explanation but I hope it heads you in the right direction. Now sure why the battery went dead unless, sometimes a relay will stick on from low voltage caused by the bad ground and cause a drain. Lots o' luck!

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Now, when I was working in the fuse box, I left the door open, leaving the overhead and fuse box lights on. Radio was pulling a tiny amount - but when I pulled the "Illum" fuse, the whole thing went away. But, I guess there's something wrong with my methods, because when I pulled the fuse it blew a fuse in my multimeter. I switched to the 20A range (different fuse).

 

Here's the weird part - when I re-connected the battery cable directly, the lights came back on, but when I pulled the fuse again, THEY STAYED ON. As though I hadn't pulled the fuse at all.

 

So, do I have a bad fuse panel? Maybe that's where my short is? Have I overlooked something?

 

Thanks for the input.

 

JT

With the lights staying on after you pulled the illumination fuse you had just proved that power is getting to the lights from another path other than the illumination fuse, on the protected side of the light circuit. I would see if you can duplicate the situation, and if you can, remove other fuses to see if you can find the other path that way. Since the car was off it sounds to me though that this mysterious connection is directly from the battery. If so, then pulling any fuses accept for some main ones may not help. The problem may be on the other side of the of the fuse panel or in the wire harness. Somehow you have a bridged connection to the courtesy lights. Though it is not a good solid connection and hense the dim lights at times. You should also check the courtesy light switch (dimmer switch) area if the other spots don't show up anything.

 

Another thought would be to suspect any directly wired accessories that have been added to the car.

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