Weird problem | GTAMotorcycle.com

Weird problem

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fen0men

Member
Hi guys I’m new to the forum and I own 2000 Honda cbr600 f4 and notice I problem with my bike yesterday when I ride around 3000 rpm the headlight dimes and the light for high beams on the dash light up the weird think happened only between 2500-3500 rpm is any body experience that kind of problem and what can be the fix
 
Wiring harness issue? Rubbed through and shorting when it vibrates at certain rpm? If it happens again, push on the high beam switch to see if that changes anything as it is possible but less likely that the problem is in the switch.
 
How old is the battery?
 
20 year old bike - 20 year old wiring.
Check all the connections and maybe give them a wee taste of dielectric grease.
 
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something about that vibration frequency
sounds like a poor connection somewhere
 
Meter test your 3 phase alternator output, the three yellow wires that come out of the motor, you might find a dead coil and as meter testing goes, it's super easy to test.
 
I am pretty sure this means your headlight is losing its ground connection somewhere in the circuit.

If the headlight circuit loses ground somewhere that is common to the low-beam and high-beam circuits, the electricity will try to back-feed through the other part of the circuit, thus illuminating the high-beam indicator even though you haven't selected high-beam. The headlight bulb itself will go almost off, because the electricity now has to find its way to ground through leakage paths (the high-beam indicator) as opposed to the proper wired ground connection.

If it only happens sometimes, when you go over bumps or when the engine (vibration) is only at a certain speed, then it's a dodgy connection, not a completely failed one, which makes troubleshooting it a royal pain. BUT ... Let's try to narrow it down.

That bike uses two separate bulbs, one for low beam and one for high beam, so I don't think the weak connection is at the bulb itself. If the bulb lost connection, it would simply turn off - nowhere for the circuit to back-feed to. Check the harness plug where the headlight wiring harness connects to the main harness. Check the wiring harness chassis ground connection, wherever that might happen to be.

There is a fair chance that a whole bunch of ground connections from various functions are brought together to a terminal somewhere inside the wiring harness ... the wiring diagram might show where that spot is. One of those may have gone bad.
 
"the headlight dimes and the light for high beams on the dash light up"

Do you mean when the low beam is running the high beam filament and high beam indicator lamp illuminates?
... check your bulb for a damaged filament, if one touches up against the other it can do that, it's called a live short in the light bulb.
 
I think the F4 was a single bulb headlight and the F4i is dual. The symptoms are exactly as what you would get for a single bulb losing ground. The dual bulb system used a relay to power the high beam and the indicator was run from the relay coil drive circuit. (wouldn't light the indicator on loss of ground)
I think this is a single bulb, and Brian is correct about the ground at the bulb. I'd try re-seating the connector at the bulb first, it has a tough life connected to that (very hot) bulb.
 
Brian P said:
I am pretty sure this means your headlight is losing its ground connection somewhere in the circuit.

If the headlight circuit loses ground somewhere that is common to the low-beam and high-beam circuits, the electricity will try to back-feed through the other part of the circuit, thus illuminating the high-beam indicator even though you haven't selected high-beam. The headlight bulb itself will go almost off, because the electricity now has to find its way to ground through leakage paths (the high-beam indicator) as opposed to the proper wired ground connection.

If it only happens sometimes, when you go over bumps or when the engine (vibration) is only at a certain speed, then it's a dodgy connection, not a completely failed one, which makes troubleshooting it a royal pain. BUT ... Let's try to narrow it down.

That bike uses two separate bulbs, one for low beam and one for high beam, so I don't think the weak connection is at the bulb itself. If the bulb lost connection, it would simply turn off - nowhere for the circuit to back-feed to. Check the harness plug where the headlight wiring harness connects to the main harness. Check the wiring harness chassis ground connection, wherever that might happen to be.

There is a fair chance that a whole bunch of ground connections from various functions are brought together to a terminal somewhere inside the wiring harness ... the wiring diagram might show where that spot is. One of those may have gone bad.
Click to expand...

is a single bulb and when that happens the headlight dimes tomorrow I will check all the connectors for loose ground and I check the harness is only one ground connection point on the harness I just wondering if I add other ground will that fix the problem
 
If it is a single bulb it has 3 contacts and 2 filaments inside the same bulb. Buy a new bulb, you're going to need one sooner or later anyway and then you have something to troubleshoot with imho.
 
If single bulb, first step is unplug and plug it in again, if it happens again then replace bulb.
 
Visually inspect the bulb while you are at it the problem might even be obvious on close inspection.
 
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