Headlamps died - cold

[julianop]

I was going to pop back in to work this evening, ostensibly to finish up a few things, though more an excuse to ride around in the cool evening air, but I didn't make it out of the driveway: the headlamps wouldn't work - neither dip or main. The markers, tail light and brake lights all work fine.

There's a relay, isn't there, that holds off the lights until the engine has started; is that the most likely culprit?

My bike has a pair of Hella FF50's taken from the take-off point on that relay (were there when I bought the bike), and a pair of cheap-o fog lights I like to use as DRLs on the dipped side (I added them recently). Is it possible I'm overloading the relay with the extra current load? Once I've fixed the problem, should I use the take-offs to drive a relay and take a fused supply directly from the battery?

[T Cro ®]

Yes you should never add heavy loads such as add on aux lights to the bikes wiring harness; they should be powered off of a fused relay tapped straight to the battery with heavy gauge wire.

Not only is there a relay in the J-Box that works the lighting it also has it's own fuse also in the J-Box so hopefully all you've done is to blow the fuse with the improperly installed aux lighting.

[julianop]

On inspection, I can see the situation. When the OE had the first set of aux lights fitted the technician properly added new, separately fused (15A) heavy gauge wiring to supply the headlamp relays up by the front forks, just like you say, T Cro. This gave additional capacity to supply the auxiliary lights, so I'm not abusing the wiring harness. What happened last night is that the 15A fuse blew. 55W * 3 /12 = 13.75A, and the current of three 55W bulbs increases to over 15A at 13.5V, so that fuse is actually undersized.
I'll have to look at the rating of the lighting relays to see if it is sufficient for the extra lights; if not I'll have to add additional relays. For now, and since the existing setup lasted me a year before I added the fogs to the low  beam circuit, I've simply replaced the fuse for another 15A device, and put a couple of spares in the stuff box; that'll get me home to Minnesota this weekend where I can look into it more deeply.

[SteveJ.]

On inspection, I can see the situation. When the OE had the first set of aux lights fitted the technician properly added new, separately fused (15A) heavy gauge wiring to supply the headlamp relays up by the front forks, just like you say, T Cro. This gave additional capacity to supply the auxiliary lights, so I'm not abusing the wiring harness. What happened last night is that the 15A fuse blew. 55W * 3 /12 = 13.75A, and the current of three 55W bulbs increases to over 15A at 13.5V, so that fuse is actually undersized.
I'll have to look at the rating of the lighting relays to see if it is sufficient for the extra lights; if not I'll have to add additional relays. For now, and since the existing setup lasted me a year before I added the fogs to the low  beam circuit, I've simply replaced the fuse for another 15A device, and put a couple of spares in the stuff box; that'll get me home to Minnesota this weekend where I can look into it more deeply.

You could add a relay controlled by dip or main to run the extra lights you added off of the ones properly installed before. Just put  the relay in before the old lights, using that power as your controlled circuit. Easy peasy. You would avoid a whole new circuit this way. I've used that set up for almost ten years, and about 150k miles with no issues. Try to avoid China relays, though...Good Luck.

[julianop]

Sounds like a plan Steve, however I have one issue...
As all the front lights are now off the same fuse, if that fuse blows, I'm completely in the dark - not a good thing.

Thinking about this further, I'd like to run the switching circuitry (relays and such) off the original wiring, fused from the original 10A fuse in the J-box, and drive relays controlling separately fused circuits off the new, high current (20A) feed off the battery. This would be something akin to a domestic power distribution system, where you have a large main fuse (or circuit breaker these days, of course) to protect the main feed, then smaller fuses to protect the individual circuits.

As a peripheral question, I see in the circuit diagram in the manual a special circuit that is supposed to provide minimum lighting by illuminating the remaining filament in the event that one filament fails. I also see a headlamp bulb failure warning light shown on the schematic. I don't see any evidence of that in my 2006. Am I missing something? Presumably the minimum lighting circuit won't work if there are aux lights installed, as they will draw current and mask the loss of the primary filament.

[SteveJ.]

I misunderstood, I thought you had a separate circuit for the previously installed aux lighting. I have an aux power panel on my bike, using a 40 amp relay and 30 amp fuse to feed it. I have six circuits on it:

Aux lights,
Headlamp, using a Murph style bypass harness.
Grip heat and Fiamm horns
Electric clothing
On dash power outlet
Under seat power outlet.

Using a relay to switch between the two sets of aux lights will result in the need for one circuit, plus a separate one for the stock headlamp.

Please note that the headlight failure circuit was eliminated in '94, along with other seemingly minor changes. You might wanna double check the coverage dates/countries on the schematic.

[julianop]

The technician appears to have patched the original headlamp circuit into the new fused circuit, then added the main beam driving lights (a pair of Hella FF50's) into that circuit. As I've used that configuration with no problems for 13,000 miles, I assumed that simply adding my own dipped beam aux lights (a pair of Walmart Burners) onto the corresponding dipped beam leg would work. Either the surge current into the Burners is higher than into the Hellas, or the act of starting the bike with the Burner's switched on caused higher load. The lights are working now with a 20A fuse, but the "all or nothing" wiring is still not good from a safety point of view.

I do want to wire the beast for electric clothing for the winter, so I'll investigate the aux panel: I'd rather do the whole thing properly in a planned fashion than nickel and dime it and end up with an inelegant mess.

Thanks for your valuable input, Steve. Oh, last thing: did you use the BMW-style Powerlets ?? is there anything better?

[SteveJ.]

With that 20 amp fuse, I hope you are not using smaller than 12 ga wire, 14 ga at a bare minimum, and the current is not going thru the J-box.

[T Cro ®]

With that 20 amp fuse, I hope you are not using smaller than 12 ga wire, 14 ga at a bare minimum, and the current is not going thru the J-box.

While I do not personally recommend it 14 AWG will support 20 amps for lengths under 18 feet.

Note that wire sizes for lighting is more critical than for other applications — The rated output of a lamp is figured at 13.5 volts, not 12. So with a 1/2 volt drop you are at 13.0 volts. And at 95% of the rated voltage, you are only putting out 80% of the rated luminous intensity - for a 100 watt lamp that’s only 80 watts!! Get what you pay for and figure to the high side when you are sizing wire for lighting.

[julianop]

SteveJ: no, the new wiring comes straight off the battery via a inline fuse. I will have to check the gauge, but it looked like 14.
My concern now is that the current also goes through the primary headlamp relays, which I'll bet are not rated for three 55W loads - that'd be 12.2A at 13.5V, and that's ignoring turn-on surge. I'm going to rewire it such that the main headlamp circuit only powers the relays for the aux lights, and the main power for them comes off the new circuit, connected directly to the battery through the fuse.

Recommendations well noted, T Cro; I'll upgrade the new feeder, especially if I'm going to add outlets for electric clothing.

[julianop]

Well I'll be darned...

I just found out that my Connie has Murph's headlight Wiring Harness Upgrade. That explains the extra relays and the tails for the main and dipped lights that aren't on the regular schematic.

Well now I feel more better... but it still doesn't explain why I popped even a 25A fuse when I started the engine with the dipped aux lights on. I took those things off, and will get something better. I like the idea of fog lights as DRLs and for my weekly after-dark slabbing commute through Wisconsin.