1998 1100RT Tail light bulbs keep burning out etc.

Heya!

Last week while riding with my brother, he noticed that my brake light wasn't working; only my running tail light was illuminated. So, I removed the brake bulb and left the tail light bulb in until the next day when I went by the shop to buy a new bulb. Well, we found that the remaining bulb was blown out (a hole in it, like it popped from over heating). We replaced both bulbs and found that the brake light remains illuminated, as if a switch is continuously on, so I left the brake socket empty and went on my way with a new bulb in the tail light. Then, when I got home from a ride today, I found that the new bulb was blown out in the same way...

So,
1) Any ideas as to why the brake light might stay illuminated even when neither brake is engaged? AND -
2) Any ideas as to why these bulbs keep popping?

Thanks!
N

Behind your right side foot plate is a micro switch that is activated when you press the brake pedal. Betcha it's stuck... Well, it might be.

Had similar happen (without holed bulbs though) on a long ride so stopped at Wally World for a small can of WD40 and had at it. That loosened it up and fixed it till I got home and installed a new one eventually. Guys kept telling me my boot must be resting on the brake but unlikely I'd pick up that habit after so long.

I think I burnt out about twenty brake light bulbs when I got my first R1100RT because I rested my foot on the pedal. I installed a little red light on my dash that reminds me not to be stupid.

Blown out glass without the accompanying melted stuff is almost always vibration. Those little, itsy bitsy, tiny plastic nuts do come loose and if the tail light assembly is allowed to move around a bit, you get the vibration and then the bulb blows out, usually 180 degrees to the seam.

I've tried getting my 1" impact on those damn little nuts. No luck yet but if I do, I will let you know.

For us feeble fat-fingered fellows, use a 19 mm 12-point socket (not "deep") to remove the nuts.
Add your ratchet extension, easy-peasy.
Do NOT use the socket (nor a ratchet) to reinstall the nuts - "very hand-tight" only; smear just a little bit of silicone adhesive on the male threads so vibration won't loosen them.

And if that rear switch isn't stuck, it is adjustable.

I use a tooth washer under each of those knobby nuts to keep them from becoming loose. Did this after finding my RT tail light hanging by the wire harness one day.

Blown bulbs

Sometimes an intermittent connection will cause bulbs to blow by spiking the voltage. Just like the way ignition points and coils cause a sparkplug to fire. The continuous voltage surges do the bulbs in. I've had it happen in my house wiring, auto and bike, AC and DC, and not the band. Look for a lose or corroded connection, from the bulb socket, the wiring connections in the tail light housing to the switch, to the harness. While you're looking at connections, clean, tighten and coat with a weather proof protectant.

Good luck!!

Lowndes

Great! Thanks for all the input. I will investigate further with this info in mind...

Cheers!

Cheap bulbs

I had a similar problem that was diagnosed as "china disease". Once I put high quality bulbs in, the problem went away.

Post 6 - right on. The stock bulb sockets aren't the best things around and the corrosion may be right inside them.

Post 5 - I really would not do that: any "toothed" lockwasher (whether it is internal tooth or external tooth) does its job by digging into the mating surface, in this case plastic. That plastic is not very strong, and it is a vibration area. Digging into the plastic may be asking for stress cracks over time. JB Weld does not adhere to this plastic. If you want a wider surface grab to distribute the load, use a thin fender washer (1/4" I.D. and maybe 1" O.D.?); then the drop of sillycone.

I agree with post #6 and with post #8. Voltage spikes kill bulbs. And crappy bulbs die of their own volition. So my approach would be to assume crappy bulbs and get a high quality European bulb. If that bulb fails soon, then get after what might be causing the voltage to be irregular and at times too high.

It's not likely that the voltage is too high - if vibration is the culprit, it's the current:
When a bulb is "Off" (and/or cold), its filament's resistance is very low.
At the moment of turn-on - including the repeated turn-ons of vibration - that low resistance causes higher-than-normal current to flow into the bulb, until a very brief moment later when the filament heats up (creating light!), its resistance goes up, and current is thereby reduced to normal (note that current is usually determined by the load, not the source).
So what happens is that the repeated spikes of "Inrush Current" kill the filament.
And yes, better quality bulbs will take more of this abuse.

Searching for Osram bulbs on eBay found me a nice supply of quality OEM bulbs. BMW used Osram even on airheads and my oilhead came with them from the factory. The real Euro made bulbs last longer than the stuff from the LAPS.