Please help!! CBR125 | Page 2 | GTAMotorcycle.com

Please help!! CBR125

Wandering back to the original poster's specific problem - which APPEARS to be first a failure of something protected by the main 30-amp fuse. Discount the "all the fuses blew" statement for the moment because - at the moment and in the absence of any other information - there is no plausible reason for why this would happen, so discount it as "improper diagnosis" for the moment.

Diagnosing electrical faults requires diligence to the extreme. You have to know exactly what is switched on, what is switched off, what's plugged in, and what's unplugged at the moment that the fault is revealed. BE DILIGENT with everything that follows below.

DC power to the whole bike goes from the battery to the 30-amp main fuse then to the ignition switch then to the fuse box which contains 10-amp circuits for all of the smaller circuits in the bike (e.g. ignition, fuel injection, headlamp, all other lighting, cooling fan, horn). Normally a fault in any of the smaller circuits would blow its own local 10-amp fuse and NOT the main fuse, and not "all the fuses blew". The only thing, aside from the ignition switch, that is normally protected by the 30-amp main fuse and which is *not* protected by any of the local 10-amp fuses is the charging system regulator/rectifier. So ... Start with that.

First thing to do is unplug it. It's on the left side of the bike underneath the side fairing, and it's a dark grey thing with a whole bunch of fins on it and either one or two (I don't recall) electrical plugs leading into it. Switch the ignition switch off, then unplug the voltage regulator completely.

Then ... Inspect all fuses for condition, including the main one, and replace any blown fuses. If the main fuse blows the instant you plug it in, even though the key is switched off and the voltage regulator/rectifier is unplugged, STOP, and advise us here on this thread, that this is what happened.

Now ... Charge your bike's battery using a suitable battery charger. Using a voltmeter (or multimeter set on an appropriate range to measure DC voltage) check the state of charge of the battery. If it is 12.6 volts or more at rest (charger not connected) it's charged enough. If it's 14.0 volts or more with the battery charger plugged in and charging, it's charged enough.

At this point you have a charged battery, all fuses are good, and an unplugged charging system and the key is switched off. Make sure the engine-stop switch on the right handlebar is in the "run" position.
Turn on the key and tell us what happens.
- What's supposed to happen: Instrument cluster lights up, taillight comes on, engine "FI" fuel injection lamp comes on momentarily, neutral lamp comes on, fuel pump makes a whirring noise for a few seconds before stopping.
- If nothing whatsoever happens, check the condition of the main fuse. If it blew, you either have a shorted ignition switch or a major short-to-ground in the wiring harness. STOP. Advise us here on this thread, that this is what happened.
- If nothing whatsoever happened and the main fuse is still good, and the battery terminals are secure, your next investigation point is the ignition switch. I do not think that this is what is going to happen.

If in the above step, what happened is what was supposed to happen, then press the "start" button and start the engine. It should start. The headlamp should come on. You will not have an operational charging system, but the engine should start and run for as long as the battery retains a charge (several minutes).

If at any point in the above steps, something happened that is not what is supposed to happen, advise in this thread EXACTLY what happened that wasn't supposed to happen. Be PRECISE and COMPLETE in your explanations. Exactly which fuse blew, exactly which lamp did not come on when it should, exactly which lamp came on when it shouldn't.

If you get this far then the fault probably involves the charging system. Further diagnosis to be explained at that time.
 
:whistle: somebody didn't read all the service manual I linked on page 1
 
Brian P said:
Wandering back to the original poster's specific problem - which APPEARS to be first a failure of something protected by the main 30-amp fuse. Discount the "all the fuses blew" statement for the moment because - at the moment and in the absence of any other information - there is no plausible reason for why this would happen, so discount it as "improper diagnosis" for the moment.

Diagnosing electrical faults requires diligence to the extreme. You have to know exactly what is switched on, what is switched off, what's plugged in, and what's unplugged at the moment that the fault is revealed. BE DILIGENT with everything that follows below.

DC power to the whole bike goes from the battery to the 30-amp main fuse then to the ignition switch then to the fuse box which contains 10-amp circuits for all of the smaller circuits in the bike (e.g. ignition, fuel injection, headlamp, all other lighting, cooling fan, horn). Normally a fault in any of the smaller circuits would blow its own local 10-amp fuse and NOT the main fuse, and not "all the fuses blew". The only thing, aside from the ignition switch, that is normally protected by the 30-amp main fuse and which is *not* protected by any of the local 10-amp fuses is the charging system regulator/rectifier. So ... Start with that.

First thing to do is unplug it. It's on the left side of the bike underneath the side fairing, and it's a dark grey thing with a whole bunch of fins on it and either one or two (I don't recall) electrical plugs leading into it. Switch the ignition switch off, then unplug the voltage regulator completely.

Then ... Inspect all fuses for condition, including the main one, and replace any blown fuses. If the main fuse blows the instant you plug it in, even though the key is switched off and the voltage regulator/rectifier is unplugged, STOP, and advise us here on this thread, that this is what happened.

Now ... Charge your bike's battery using a suitable battery charger. Using a voltmeter (or multimeter set on an appropriate range to measure DC voltage) check the state of charge of the battery. If it is 12.6 volts or more at rest (charger not connected) it's charged enough. If it's 14.0 volts or more with the battery charger plugged in and charging, it's charged enough.

At this point you have a charged battery, all fuses are good, and an unplugged charging system and the key is switched off. Make sure the engine-stop switch on the right handlebar is in the "run" position.
Turn on the key and tell us what happens.
- What's supposed to happen: Instrument cluster lights up, taillight comes on, engine "FI" fuel injection lamp comes on momentarily, neutral lamp comes on, fuel pump makes a whirring noise for a few seconds before stopping.
- If nothing whatsoever happens, check the condition of the main fuse. If it blew, you either have a shorted ignition switch or a major short-to-ground in the wiring harness. STOP. Advise us here on this thread, that this is what happened.
- If nothing whatsoever happened and the main fuse is still good, and the battery terminals are secure, your next investigation point is the ignition switch. I do not think that this is what is going to happen.

If in the above step, what happened is what was supposed to happen, then press the "start" button and start the engine. It should start. The headlamp should come on. You will not have an operational charging system, but the engine should start and run for as long as the battery retains a charge (several minutes).

If at any point in the above steps, something happened that is not what is supposed to happen, advise in this thread EXACTLY what happened that wasn't supposed to happen. Be PRECISE and COMPLETE in your explanations. Exactly which fuse blew, exactly which lamp did not come on when it should, exactly which lamp came on when it shouldn't.

If you get this far then the fault probably involves the charging system. Further diagnosis to be explained at that time.
Click to expand...
Brian op said they checked the battery, op sounds like a new rider...I’m wondering if they put the battery in and wired negative to positive and positive to negative and blew the main fuse that way. That would explain the main fuse blowing wouldn’t it? OP did you remove the battery or just checked the voltage of it connected still?


- Nevermind sounds like main fuse blew before battery check
 
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I've had a bad alternator on a car fry the main fuse so would / could a bad regrec cause it on a bike ? Putting out to much AC or DC What area is the OP in to possibly help.
 
It's conceivable. The reg is normally on an unswitched connection to the battery through the main fuse. A short in that circuit will blow that fuse regardless of engine running or not, key on or not. If it is a dodgy connection, vibration from running engine or road vibration could lead to blowing the fuse only when those conditions exist.
 
Check the contact points on the battery. They need to be clean metal, no corrosion should be visible.

Make sure positive to positive and negative to negative.
 
GVH said:
I've had a bad alternator on a car fry the main fuse so would / could a bad regrec cause it on a bike ? Putting out to much AC or DC What area is the OP in to possibly help.
Click to expand...
Everything you said was correct except you added "regrec" instead of alternator. The alternator can put out too much or too little AC. Typically there are one, two or three wire wound coils inside the alternator that can short.
The alternator is the power source, the rectifier is an array of diodes and the regulator dissipates excess power in the form of wasted heat. If the regulator circuit includes a capacitor, that is in there to smooth the power output. (turns it into a straight line and not a wavy line when you look at it with an oscilloscope ) Capacitors store power for when you need more of it, they are similar to a battery in function.
 
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