Rear bulb keeps blowing

[GraeV11]

I install new bulb, ignition on, then lights on, bulb blows. Rear brake light still works (it is burning out the rear light filament). The bulb doesn't seem to 'click' into place when I install it, i.e., it can easily be pulled out?? I have checked all connections and wires and all look OK. On my fourth bulb in two weeks now. The girl in the automotive store thinks I am stalking her. The spec of the bulb is as advised. Any ideas ? Driving me nuts. Thanks.

[Kiwi_Roy]

It's probably a loose contact causing the lamp to flicker off and on.

The thermal shock as a lamp turns from off to on is what usually takes out the filament, you must have noticed this around the home.

While the lamp is off the resistance is quite low so at the instant of turning on the current is many times normal.

[gstallons]

This is going to be a job, but remove the tail lamp housing and disassemble it. You will find two contacts that need to be bent to make a better contact. You can then fill the cavity with white grease or an electrical grease so it will keep out humidity.

[AndyH]

Sounds like you have a fairly fundamental problem here which may need addressing first, but when I had a bulb blow each outing I got LED bulbs off eBay. Goes into the same socket, no conversion needed. Bought four units just in case there was a bit more to it than vibes, but I've been running the same LED unit for 4000 miles. Worth a try?

AndyH

[Bob Hartman]

The bulb doesn't seem to 'click' into place when I install it, i.e., it can easily be pulled out??

 

 

Yeah, how about that? I had some electrical mysteries with my recent V11 and along the way found the rear bulb was in upside down. Symptom? It was bright all the time. Effect: An additional, constant 2amp draw - plus the safety aspect.

 

I also found that the socket does not allow the 1157 bulb to be twisted into place. There are two channels for the lock tabs, but no corresponding slots to accept them/hold the bulb in place. So it's a friction fit - which works - but is bewildering.

 

If you have the same situation, I wonder if the plastic socket has come out of shape.

[Bob Hartman]

Another thought after re-reading your initial post in which you said the bulb blows the rear light filament immediately - before you ride.

 

Have you had a chance to put a volt meter on the connections? If nothing exceeds 13 odd volts it sounds like a short in the socket (side of the 1157 goes to ground, does anything at the connector end encroach?). If it's significantly more than 13V you might have inadvertently figured out cold fusion.

[gstallons]

I install new bulb, ignition on, then lights on, bulb blows. Rear brake light still works (it is burning out the rear light filament). The bulb doesn't seem to 'click' into place when I install it, i.e., it can easily be pulled out?? I have checked all connections and wires and all look OK. On my fourth bulb in two weeks now. The girl in the automotive store thinks I am stalking her. The spec of the bulb is as advised. Any ideas ? Driving me nuts. Thanks.

 

 

Uh.............you are properly installing an 1157 or similar 2 filament bulb properly into the socket ?

[docc]

Three thoughts:

1) The 1157 can be pressed in 180 degrees off lighting both filaments.

2) The flat contact hoops in the socket can flatten out and cause contact issues. I've pulled mine aft with a dental probe to gather more contact with the bulb base. (I had to be pretty aggressive with it to make it last).

3) Other members have reported a trapped wire under the seat/tail cowl which shorts the tail lamp circuit - worth a look!

 

I have some other thoughts, but they'll have to post to some other forum . . .

[Guzzirider]

Have you checked your battery voltage while the engine is revving? If you are getting around 17 volts rather than high 14s then a faulty regulator / rectifier could be the cause of your blown bulbs.

[GraeV11]

Thanks for all the advice, appreciated. Good news is it is fixed, bad news is I am not entirely sure why. This is what has changed . . .

 

> Pulled the unit, checked all wires (fine), bent the contacts out a little.

> Noticed a slight crackle from the fuses when I turned on ignition. Found that one leg of the 30amp fuse had fractured (not melted I think). Was still making contact, but obviously not a good contact. The fuse had not blown (charge light not showing when engine running). I replaced it. Didn't have a spare bulb at this point.

> Bought some bulbs from a different manufacturer. These did 'bayonet fix' in the socket, but only if in the right way up (brighter with the brake on). All now working fine ! Checked packet from old bulbs, definately 12v, definately right spec (they were cheap though !)

 

These issues may obviously not be connected, I am just happy it is fixed. Electrical problems have always been the most frustrating to sort for me as it is not my area of expertise. Would be interested in your verdicts.

 

Cheers !

[docc]

The intermittent arc from a broken connection throws some terrific voltage spikes into the electrical system. Sounds like your bulb socket contacts were also flinky.

 

Very common issue - the melting/ broken/ charred 30 amp fuse:

30 amp fuse melting

 

Nasty Hiccup/ MAXI Fuse

[GraeV11]

The intermittent arc from a broken connection throws some terrific voltage spikes into the electrical system. Sounds like your bulb socket contacts were also flinky.

 

Very common issue - the melting/ broken/ charred 30 amp fuse:

30 amp fuse melting

 

Nasty Hiccup/ MAXI Fuse

 

Thanks Docc, I will keep an eye on that fuse. I would do an electrical health check now but past experience has taught me that I should wait for further issues before I dive into things that are largely a mystery to me. Let sleeping demons lie is my motto. I used to have an old Bonneville that regularly conked out with electrical problems and, well lets just say that shouting at a stationary machine at the side of the road is not a habit I want to return to.

 

Cheers

[docc]

The intermittent arc from a broken connection throws some terrific voltage spikes into the electrical system. Sounds like your bulb socket contacts were also flinky.

 

Very common issue - the melting/ broken/ charred 30 amp fuse:

30 amp fuse melting

 

Nasty Hiccup/ MAXI Fuse

 

Thanks Docc, I will keep an eye on that fuse. I would do an electrical health check now but past experience has taught me that I should wait for further issues before I dive into things that are largely a mystery to me. Let sleeping demons lie is my motto. I used to have an old Bonneville that regularly conked out with electrical problems and, well lets just say that shouting at a stationary machine at the side of the road is not a habit I want to return to.

 

Cheers

 

Perhaps then you could change the 30 amp fuse with every valve adjustment/ plug change while it's only melting and has not burned off its contacts just yet.

 

That certainly is a trouble spot in the wiring harness.

[gstallons]

If the fuse is melting or showing signs of heating up at the blade, the terminal connector has relaxed and is causing a bad connection.

Do you feel confident enough to remove the connector from the block and crimp the connector to tighten it up ?

Kiwi Roy has an article showing how to do this if you are uncertain on how to do this.

This is a major problem area with wiring terminals.

[Kiwi_Roy]

I don't have a picture of the fuse block but it's quite easy to bend the contacts so they clamp the fuse tighter. I think it's only the 30A one that gives trouble.

The fuse holder is mounted to the chassis with a couple of rubber gromets, just grab the block and pull it will come away so you can inspect the connections below as well.