Mystery light

[thewizard16]

Well, I apparently need to stop "fixing" things. I replaced a few bulbs on the car the other day and things have been fine since. Today I replaced the foglights (which are not wired into any lighting circuit- they are completely on their own) after a minor fender bender killed the last set and now I have a problem I've never had before. Every time I press the brake pedal, the left turn arrow in the dash comes on (at about half brightness, but steady lit). The brake lights still function, the turn signals work fine, but it's really annoying and I can't find what's causing it. I pulled the bulbs I replaced out and put old bulbs in to see if that affected it, but the light still came on. I haven't unplugged the foglights yet (it's tricky to get to), but I did disconnect their circuit to see if they were somehow grounding something out (even though they're not on any lighting circuit/fuse), but it still did it.

I guess this weekend I need to pull all the bulbs and figure out one at a time if one of them is causing an issue, but that's going to be a real pain. Any ideas on what might cause this?

[VTEC_Inside]

Inspect the left rear tail light wiring/bulbs.

[thewizard16]

Inspect the left rear tail light wiring/bulbs.

See, that's what I thought too but I couldn't seem to find anything last night. I swapped out the bulb (which is an aftermarket LED array, but it hadn't been causing any problems) for a traditional bulb and the problem remained. The turn signal bulbs have also been replaced in the last few weeks, but are still working and hadn't been causing any problems. I think what I'll do as soon as I can is pull ALL the bulbs and see if the problem persists. If it does, I'll know it's not a bulb at least. If it doesn't, I'll step by step add them back and see what happens. It seems like it must be a grounding fault somewhere, but I'm not sure where all to look. I also have had trouble with the spoiler light in the past (since a rear-end accident that messed it up), but it's been working fine too.

[thewizard16]

Okay- so I took apart the left rear brake light assembly again (left the center tail light alone this time) and pulled the parking, turn, and tail/stop bulbs. The problem disappeared. So I put them back in one at a time. The problem did not return (yet, anyway). I'm a little stumped as to what may have caused the error, but it's magically gone for now.

[Rupert]

One of the bulbs wasn't in right, or had some dirt on the contacts.

[hotrodalex]

The bulbs got lonely and wanted to be fondled again.

[The Pirate]

Expanding on Psilos's thought - did you check/clean the contacts and apply dielectric grease when reinstalling bulbs?  Not that cleaning contacts and greasing contacts is definitely the fix, but it's going to rule out those connections if the problem does come back.  Plus, it's good practice.  I keep a little tube of dielectric grease right in the car so it's always accessible when needed. 

Also, on that note, are the battery terminals clean and free of corrosion?  I've seen weird electric gremlins disappear after cleaning and greasing the battery contacts.