Help with headlight prob - '99 CBR900RR

[Motoracer]

I picked up a bike from trade me. Its a 1999 CBR900RR. Everything on it is mint except the headlights don't work. High beam however does work.

I thought it's a simple matter of replacing the bulbs, which I did. However even with the new bulbs, only the high beam works and not the normal headlight.

I checked the general condition of the wires that were easily visible and also the fuses. Everything looks fine.

Where is a good place to start the diagnosis? Does anyone know of any articles online that can help me? :scratch:

Thank you!

[Drew]

The fuses Sudeep, you idiot!

The connection blocks.

Then the relay.

Then the right hand switch block, (even hard wired light's circuits go through it).

[Motoracer]

I must be such a moron because I don't understand why you are calling me an idiot. lol

I appreciate your helping efforts Drew but can you please use the attached diagram to explain it a bit better? Which are the connection blocks? What should I be looking for? Damaged wiring or what?

Chur

[jellywrestler]

I must be such a moron because I don't understand why you are calling me an idiot. lol

I appreciate your helping efforts Drew but can you please use the attached diagram to explain it a bit better? Which are the connection blocks? What should I be looking for? Damaged wiring or what?

Chur

dont worry about drew, he was shaken as a baby...
most basic thing to do would be to swap the two relays around to prove they both work, it wont be a fuse as one fuse covers both lights, it wont be the right switchblock as the wire branches off before then to go to the headlight
Are the taillights working correctly?

[Drew]

I'm having a larf at you bro.

All the plugs on the loom is what I mean.

But always fuses first.

[Motoracer]

dont worry about drew, he was shaken as a baby...
most basic thing to do would be to swap the two relays around to prove they both work, it wont be a fuse as one fuse covers both lights, it wont be the right switchblock as the wire branches off before then to go to the headlight
Are the taillights working correctly?

Cool thanks for that JW. Switching the relays around is a good idea. I will check that soon.

Yep tail lights are working just fine.

P.S. Thanks for your contribution too Drew.

[Drew]

dont worry about drew, he was shaken as a baby...
most basic thing to do would be to swap the two relays around to prove they both work, it wont be a fuse as one fuse covers both lights, it wont be the right switchblock as the wire branches off before then to go to the headlight
Are the taillights working correctly?

High beam still worked on my Hornet, with the headlight fuse blown. On the RF, it doesn't work if the turn signal fuse is blown.

So I figure it's always worth checking them all.

Yeah, wont be in the right switch block, if one beam is working. Might be in the dimmer switch though.

[buggerit]

looks like you have one fuse that supplies hb & lb relays so if you have hb fuse must be ok.
Trace back from bulbs,next thing on loom is relays, both have 4 wires to them, lb one has white trigger wire( comes from switch), green wire (earth) , white wire with black trace(power to lb filaments), black with red trace(main power feed from fusebox for relays).


Put test light /multimeter on terminal with white trigger wire , making sure switch is on low beam, should have 12v, if ok possibly relay stuffed,
Check there is power at terminal with black wire/red trace.
Cut short peice of insulated wire and strip ends,remove white trigger wire from terminal and use jumper wire from terminal with black wire/red trace to terminal you removed white wire from,if low beam lights up you have a fault in trigger wire which goes back to switch gear.

Test wiring between relay and headlights by using your jumper wire between black/redtrace terminal and white/black trace terminal,
low beam should go as this bypasses relay and trigger wire.

Be careful with the jumper wire not to short it out onto chassis etc
Make sure you have a good earth with your multimeter/testlight.

[jellywrestler]

Might be in the dimmer switch though.you mean the dipswitch ya dipstick!

[Drew]

you mean the dipswitch ya dipstick!

You know Damn well that's what I meant Fuck ya.

[spanner spinner]

your cbr lights are wired up to turn off when you hit the start button, this switch can give problems when the bikes have clocked up a few k's. Find a wiring diagram on the net to give you the colours that you need to trace as this will make you fault finding heaps easier. There is a main power feed wire that feeds into a second circuit that is part of the start switch, this wire then jumps across to the high low switch. My advice would be to open up the left hand switch block and check for power feed to this switch. If there is power to this switch go looking at the other suggestions that have already been made, if there is no power to this switch start looking in the right hand switch block.

[Marmoot]

I picked up a bike from trade me. Its a 1999 CBR900RR.

Post pic, bro. Was it like what I had?

[Motoracer]

Thanks heaps buggerit! Awesome advice. Will try it out once I borrow a multimeter from a mate.

Spanner spinner, thank you as well.

Marmoot. Hey bro. Hope you are well. Its essentially the same bike as your ex bike but in custom paintjob with all the bells and whistles. After being on later model sports/superbikes, it feels strange to jump on an old school superbike but it's still a good bike!

I remember that you used to blow out the headlight bulbs with your wheelie landings, so I thought that must have been the case with this bike but no. Which is a good thing. lol

Pic attached.

[Marmoot]

Sexy!
Love the signals and the mirrors.
Need some blue and orange tho.
Grats and good luck with the lights.

For bruteforce approach if you are desperate, grab a voltmeter and check the each connection to see if you get 12v on ignition on, starting from the headlight bulb socket and working your way back through the wiring all the way back to the fuse, relay, etc.
The problem would be between the connector with the 12v and the one before that.

[jellywrestler]

Thanks heaps buggerit! Awesome advice. Will try it out once I borrow a multimeter from a mate.

you can also use a simple test lamp, any old bulb with a couple of leads soldered to it or even a spare bulb holder

[Banditbandit]

Where is a good place to start?
Thank you!

get something less ghey ???

[Motoracer]

looks like you have one fuse that supplies hb & lb relays so if you have hb fuse must be ok.
Trace back from bulbs,next thing on loom is relays, both have 4 wires to them, lb one has white trigger wire( comes from switch), green wire (earth) , white wire with black trace(power to lb filaments), black with red trace(main power feed from fusebox for relays).


Put test light /multimeter on terminal with white trigger wire , making sure switch is on low beam, should have 12v, if ok possibly relay stuffed,
Check there is power at terminal with black wire/red trace.
Cut short peice of insulated wire and strip ends,remove white trigger wire from terminal and use jumper wire from terminal with black wire/red trace to terminal you removed white wire from,if low beam lights up you have a fault in trigger wire which goes back to switch gear.

Test wiring between relay and headlights by using your jumper wire between black/redtrace terminal and white/black trace terminal,
low beam should go as this bypasses relay and trigger wire.

Be careful with the jumper wire not to short it out onto chassis etc
Make sure you have a good earth with your multimeter/testlight.

Thanks again Buggerit! Your post was the most helpful. I placed the laptop in the garage with the wire diagram and the KB posts. I invested half a day today with determination to start the diagnosis and end up with success. By the end of the day, I managed to get the headlights working! Yay! Thanks again to everyone else who also gave useful tips.

In the end, it was a case of a cut wire in the middle of the wiring loom. Had to test and trace the different points with a multimeter.

Feeling stoked!

[Drew]

Good work team!

[baffa]

Well done.

The older bikes sometimes have some odd gremlins. Mates 600TT wire perished causing it to cut out randomly. I think these things add character.

PS, shoulda bought my fireblade.