Turn Signal Repair

3157 Bulb

New improved stuff means new improved problems. Left front turn signal on my truck flaked out, started flashing double time. I shouldn't complain, the truck (Dodge Dakota) is 14 years old and this is the only light that has given me any trouble. It pulled the same trick a few months ago, so I figured it was burned out and needed to be replaced. When I inspected the bulb I could not find anything wrong, so I plugged it back in and it started working, so never mind.
     Now we're back and I pull the same bulb out again, and again it looks fine, but plugging it back in
doesn't fix the problem. At this point any ordinary mechanic would have replaced the bulb and been done with the problem. But since I bothered to look at the bulb, I wonder if maybe there is some other problem, like the socket is disintegrating or something. So we futz with it, and lo and behold, pushing the bulb halfway in causes it to light up, but pushing it all the way in causes it to go dark!
    Closer inspection of the bulb reveals what looks like scorch marks on some of the contact wires on the base, and the wire is rough to the touch, not smooth like the other contact wires that are shiny. Looks like a marginal contact was exacerbated by arcing. Scraping at this roughness with a pocketknife does not alleviate the problem, so I pull out a file and file away. It took quite a bit of filing to get rid of all of the rough patch, but it solved the problem. For now.

P.S. I didn't take a picture because I didn't, and I should be able to find a picture of this bulb out there on the internet easy enough, right? You wouldn't believe how many pictures of the wrong turn signal bulb are out there. A zillion at least. Even this one isn't perfect. This one has a plastic base, the one in truck is all glass.