Headlights playing up

[gbren]

Hey Guys,

Had my NC35 for about 2 months now, been reading this forum for about 2 years now but never joined as I had different bikes.

I am quite handy with a set of tools and have had a decent play with the bike but have not been able to narrow down what is wrong with my headlights.

I had a major service done and the mechanic told me that my left hand switch was "Abnormal" it worked perfectly fine before I gave it to him but whatever.

THe problem is that I have no low beam anymore, My high beams work with the passing switch at the front of the block and also the push button switch but my low beams which were previously always on as soon as turned on the ignition are gone :/ (My horn is now not working either)

The switch itself looks fine to me, it is clean, there are no breaks or damaged wires, everything is plugged in and the fuse box has no blown fuses.

Would you guys be able to help me narrow this down.

Thanks
Deniz

[magg]

When you say the switch looks fine, have you actually dis-assembled it to look at the contacts?

With a multimeter, unplug the handle-bar connector and measure the resistance between the blue/white and white wires. With low bean selected the resistance should be less than 1-2 ohms. A higher reading means the contacts are probably burnt/dirty and you need to clean them.

[CRM]

switch burnt out ? not running regular H4 bulbs 55/60w bulbs are we ? if so there is your problem.

[speedy231278]

It's the usual switch problem. The switch carries ALL the load on the NC35, and even with the correct Japanese spec 60/35 H4s in them, they have a habit of breaking. I've had mine 10 years now, and I reckon I'm on the fourth light switch, and two of those were brand new genuine ones. I swapped to 60/35 from using UK spec 60/55, and I'm sure that on at least one occasion this situation has cropped up. It usually happens a few times and corrects itself before the thing dies. For some stupid reason, despite the fact that there's a relay to turn the headlights off when the starter is engaged, all the load goes through the contacts of the switch even though you can't turn the lights off manually. So when you hit high beam, all 190W (Japanese spec) or 230W (UK spec) go through the tiny contacts in the latching switch. This builds up a lot of heat, and the part that carries the sprung contacts goes soft, and eventually the contacts for the low beam get jammed in, and cannot make contact with the terminals in the switch. This leaves you with high beam only. If you're really unlucky, high beam will give up the ghost too, leaving you hanging on the passing switch for any light at all! I had this happen on one occasion, and bizzarely after a few more miles it blew the fuse for good measure. Fortunately the ride home was in the light, and a new switch and fuse cured the issue.

There are two solutions to the issue, and ideally both should be done. The first is to get some Japanese spec headlamps, 60/35W H4. They're not cheap, mine cost over a tenner each about 18 months ago, but then there were genuine Honda parts labels on the bags. 34901-KY2-701, currently £14.50 from David Silver. The switch is silly money. I've bought at least two brand new ones from David Silver, and they must have found a pile of them as NOS from someone else, because the current price has rocketed. 18 months ago I paid £49, a year before that I paid £39. Yes, the BRAND NEW one lasted a year, and I NEVER used high beam except for the MOT before it died as I knew the 60/55s would overload it on full power, I was too ignorant to think that the low beam side of things was the real issue. 35200-MR8-900, it's now an almighty £109.57!! What's worse is that's ex VAT... Usually crop up on eBay, but don't bank on them not being a bit dodgy either. I really don't see why Honda didn't hard wire them straight in and out of the relay that cuts them when you engage the starter...

The second thing is to do the relay mod to the wiring. If you go to the document library on the home page of this site (ie, not the main page of the forum) there's a guide to inserting a relay into the system. You end up using the light switch to energise the relay instead of the headlamps, so there's much less load on the switch as the relay carries the lighting load instead. I guess if you were clever enough you could use two relays, and take the output for high and low beam to the headlamps via a relay each, but I'm not sure which side of the switch the relay is that turns them off for starting, so you might end up accidentally bypassing that....

I have to say that I could swear that with the correct Japanese spec headlamps despite the lower wattage on low beam everything seemed brighter when I first used them. I can't help wondering if it's not just the legs on the base that are different, and if something about the beam pattern is too. I'm convinced the spread of light was far superior despite being about 1/3 less power.....

[magg]

Speedy231278, some of your wattage numbers are excessive. Two 60W high beam lamps totals 120W not 190W or 230W. You appear to believe high beam has all four filaments on.

All NC30s and NC35s have relays for high beam, UK spec NC30s also have a relay for low beam because UK NC30s come std with 55/60W head lights. Non UK NC30s and all NC35s do not have a low beam relay, which is why when 55/60W lamps are fitted to a non UK NC30 or an NC35 a relay should be fitted to reduce the load on the Hi/Lo switch. A further benefit from relays is that smaller wiring losses should mean higher voltage at the lamps and thus brighter light.

As I have said in other posts, IMO a relay in the low beam circuit for all NC30/35 is a good idea.

On and NC35 there is no relay to turn the low beam off when starting the engine. There is simply a set of contacts in the start switch, much like those in the Hi/Lo switch, that open and close when the start button is pressed.

[speedy231278]

Erm, yes, I did/do think that you get all four filaments. Surely a whole 5 watts extra wouldn't notice unless there's something dramatically different in the reflector? I guess there is... I always thought that the relay was operated by the starter switch, but come to think about it, what the hell did I think the click was when hitting high beam if it wasn't a relay?

This evening I will be mostly pulling out a headlamp to observe what the filaments do.... lol

I got the bits together on one occasion to do the relay mod and couldn't find the right wires on the connector, and they seemed to be a different colour than the wiring diagram, however I'm going to persevere with that as I could do without another self destructing switch come the winter and I'd like to be able to use high beam without carrying the worry that the switch is going to pack up regardless of the headlamp wattage!

[thunderace]

Erm, yes, I did/do think that you get all four filaments. Surely a whole 5 watts extra wouldn't notice unless there's something dramatically different in the reflector?

It's the shield inside the bulb over the 55w filament that directs light to certain parts of the reflector to create the dipped beam

Cheapy pound shop bulbs often don't have the shield in the correct position, hence distorted beams when using cheap bulbs.

[speedy231278]

Ah, I get it now, I guess that also works in conjunction with the grey tip? I'll have to see about firing up the soldering iron this weekend if I can trace the wires in the connectors. It's 'only' finding a positive, a ground, interrupting the feed to the lights and isolating one end of it.... Might sound a silly question, but instead of cutting the white wire from the switch, could you not simply remove it from the connector and solder it to the relay seeing as the other side of the connection becomes redundant? I don't intend reverting to the factory setup if I get it right, but I'm always loathe to modify the loom side of things unless there's no other choice!

[magg]

5 watts, don't you mean (55-35) x 2 = 40 watts total difference between lamp types. If you do not want to cut the white wire on the loom side of the connector and you are happy to cut it in the switch side, the outcome will be the same.

[speedy231278]

By 5 watts I was referring to having 60/55s fitted and 5w a side difference from going low to high beam (so 10 in total). Now I've twigged the difference in the filament arrangements I understand why these 5 watts per side with the wrong amps could have seemed to make so much of a difference. So, yes, 20w per side different with the correct ones fitted. I assume that the filament shielding is different too, and why the low beam actually appears better with less watts from the right bulb than with more from the wrong one!