Burning out tail lights and brake lights

[Fix]

I'm going through 1157 bulbs like candy. I'm getting 11.5v on the tail light lead, and 11.5 on the brake light lead when the brake switch is activated. This seems wrong to me. Anyone know the proper voltages, or why I'm blowing bulbs?

The 1157 is supposed to be 8v tail and 23v brake, I thought. These are the blue to ground, and green/yellow to ground readings.

[Fix]

Unless I'm measuring this completely wrong it appears I'm getting 12A on the tail light and 12a on the brake when triggered. If that's the case it would sure explain the burnt out bulbs. Any ideas why I'd have so much current on those connections?

[natemoen]

You should be getting battery voltage at the light (12-14.5v). The 8 and 23 you are talkung about is the wattage of the different filaments in the bulb. Don't know about the amps but 12 does seem way high.

[Fix]

You should be getting battery voltage at the light (12-14.5v). The 8 and 23 you are talkung about is the wattage of the different filaments in the bulb. Don't know about the amps but 12 does seem way high.

Thanks Nate, so the voltage is probably good. But I need to figure out what the current is doing. The leads on the multimeter were warm to the touch after measuring the amperage.

[sparks]

Also depoends on where you took the reading. There is a good possibility that your draw is from dirty bulb sockets or in one or more connectors or splices. Could also be in the path to ground.. I would check on all of those..

Regards,
Lee
(Sparks)

[Fix]

Also depoends on where you took the reading. There is a good possibility that your draw is from dirty bulb sockets or in one or more connectors or splices. Could also be in the path to ground.. I would check on all of those..

Regards,
Lee
(Sparks)

I disconnected the fixture and I'm checking at the wire ends. Would the amps increase because of a splice going bad somewhere?

I checked from wire to shock mount (for my ground) I'll check my ground strap, but I'm not having issues anywhere else, electrically.

I hate electrical, I have no clue what I'm doing

[crazy steve]

One thing you can try is getting actual motorcycle lamps (yes, there is a difference). The automotive type can work in a bike, but they're not as heavy-duty as the motorcyle versions. Any bike dealer will have them, they're bit more expensive but may cure your problem...

[Fix]

One thing you can try is getting actual motorcycle lamps (yes, there is a difference). The automotive type can work in a bike, but they're not as heavy-duty as the motorcyle versions. Any bike dealer will have them, they're bit more expensive but may cure your problem...

I didn't even realize there was a difference. I'm taking apart the harness right now to see if there's any obvious damage. Did find some water in one of the sheathes up by the headlight. It's not the one carrying the culprit wires, but it could be affecting it.

[TopCatGr58]

Hey Fix,

The fuses for the lights are rated at 10 amps, the turns 20. Not sure how you were measuring the AMPS on the line, but if the wires got warm, then you were able to put almost the full draw the line was capable of.

The bulbs as stated are supposed to be 8 and 23 watts, which are only 3/4 of an amp, to almost 2 amps for running and brake light filaments. The circuit should only draw what it needs to run these bulbs. If there was a SHORT on the line that would usually cause you to blow fuses because too much power/amps would be allowed to flow directly to ground without any LOAD=bulb generating light and heat. You didn't say you were blowing fuses, just bulbs.

So...like Steve said, the MC specific bulbs are designed with stronger filaments to not get shaken and broken so easily.

I'm no electrical guru, just a basic knowledge of simple circuits and principles.

You measured the bulbs lines voltages I'm assuming with just the key on, not necessarily with the engine running. Have you checked your voltages across your battery with the bike running at both idle and ~2500 rpm? Should be near 12 volts to 14.5 respectively. If you're seeing much higher voltages then the REG/RECT may be malfunctioning and providing TOO MUCH voltage which could also fry your bulbs? JAT!

T.C.

[sparks]

Basic Ohms law... anything that causes the resistance to go up wi8ll cause the currant to go up with the same voltage aplited... A crimp splice that has some corosion going on will increase the restance. You might want to use your multimeter to measure the resistance in the tail lamp circuit. I would put a jumper in place of the bulbs (a dime might work). A five foot piece of 14 guage wire shouldnt even have an ohm of resistance.

Lee

I disconnected the fixture and I'm checking at the wire ends. Would the amps increase because of a splice going bad somewhere?

I checked from wire to shock mount (for my ground) I'll check my ground strap, but I'm not having issues anywhere else, electrically.

I hate electrical, I have no clue what I'm doing

[Fix]

I just read the manual on the multimeter and it said that amperage is tested in series with the circuit being tested.

I was just touching the red lead to the blue wire and grounding the black lead...

SO I think all my amperage readings are bunk.

Of course, this realization is being made AFTER I opened up the whole wiring harness, stem to stern.

[conquest87tsi]

Multimeter

I'm surprised you didn't blow the fuse on the meter. Amps are always read in series.

[Fix]

I'm surprised you didn't blow the fuse on the meter. Amps are always read in series.

Yeah, I'm reading up. I had the meter in series, but no load in the circuit. Just blue wire (running light) to red lead, black lead to ground.

So I'm going to get a new bulb to put in the circuit to test.

[Fix]

Ok, with a bulb in place i'm reading .5 amps on the blue wire, which is in spec. Going to test the green/yellow now, but I have a feeling that it will test good as well. We may very well be looking at a case of cheap ass auto bulbs shaking to death...

Thanks guys!

[skids]

(snip)
You measured the bulbs lines voltages I'm assuming with just the key on, not necessarily with the engine running. Have you checked your voltages across your battery with the bike running at both idle and ~2500 rpm? Should be near 12 volts to 14.5 respectively. If you're seeing much higher voltages then the REG/RECT may be malfunctioning and providing TOO MUCH voltage which could also fry your bulbs? JAT!

T.C.

T.C. is on the right track here.