CBR125 Electrical fault

Hello all first post ever on a forum from me so sorry if I'm doing something wrong.

I have a honda CBR125 2012 model. I came across a problem a while ago, I went to turn the key on in the evening and nothing happened. No fuel pump sound, no lights, no horn, no dash startup, no neutral light.

I just bought a new battery also so I found this awfully weird. I checked the battery connections and they was fine so I went to try and bump start it. I failed the first two times but after the second one I put the breaks on down the hill and stopped. All of a sudden everything came to life. The bike worked as it should and how it has been working for 2 months.

Now 9 days after this issue I went to Birmingham bike festival. I turned the key to turn the bike off, asked the man where bikes park, then went to go sit on my bike, turned the key and again... nothing. Very weird how it's just stopped working when i cut power to it but for 9 days it was working fine.

So after being picked up I took the whole thing to bits and have been trying to diagnose any problem I can find. But there is literally NOTHING wrong with the electrical circuit. I have got a voltage to every component a strong voltage, I have charged my old battery and new battery up and tried them both to see if anything new happened but nothing.

At one point I thought the issue was the ignition switch from many people telling me they had the same problem. I took it out then checked continuity across when the key was turned on. I got 230 ohms so just in case I connected a wire across the two contacts on the connector block.

This did not make a difference, I am still getting battery voltage to every component and every fuse. All fuses have been checked including the main fuse for continuity and i even swapped them around and tried using the spares.

I have checked all the relays to check the switch closes when battery voltage is applied. The only thing I can say about the relay is that the short buzz it is suppose to make is random. Sometimes you can hear it when you turn the ignition on, sometimes you cannot, I do not know how it was before but the fan relay is the same anyways so i have tried swapping them around but no difference.

Now another weird thing that happened is when I charged my new batter up (approx 14 volts) I used some wire to connect the two contacts that the relay switch would normally do. Nothing new happened again but after about 7 mins of me double checking my voltages BAM!!! all of a sudden I have life again. It stayed on for a while and i gave it a lil nudge to check i didn't move anything. I tried to start the engine, I heard a pop and then it shut off again. Checked all fuses nothing has blown, relays still working. Hasn't turned back on since.

I have had my mentor around today and he cannot see a reason why it should not work either. He told me to make a forum and try to get my hands on a new ECM as loads of the components go through the ECM before they go back to the battery to complete the circuit by looking at the Wiring diagram. I am going to try and do this but in the meantime if anyone could help it would be a god send because I am beyond frustrated with this problem now. (Only just started riding not filling me with happiness with it in pieces)

Thank you for whoever got this far but I tried to be detailed as possible.

p.s. I'm pretty certain my bike DOESN'T have a factory fitted immobiliser but if it does please let me know.

I have got images of the electrical drawing but I am not sure how to add pictures on here -,-

Hello! if you start a new post then select attachments under the text box you can upload images

AWESOME got the pictures on thank you Hoggs

Hello and welcome to the forum . What this sounds like to me is a dodgy battery connection. Get some medium sandpaper and rough up the battery terminals and the plates on the battery leads so there is good metal to metal contact and re tighten the bolts firmly . Might not be the cause but it always pays to start with the simplest and cheapest fixes first . If this doesn't cure it then start looking at various block connectors . A good way of cleaning these , or at least the male halves, is to make a little tool by gluing fine emery paper to the inside faces of a pair of broad tipped tweezers. All you do is grip the blades inside the connector and give them a gentle rub to remove any tarnishing. Don't go spraying WD40 all over everything it just attracts more muck . Good luck .

I had a CBF125 2012 with weird electrical problems, what you need is to get it plugged into a Honda diagnostics machine. There maybe cheaper alternatives. It might help you narrow down the problem. Shorting parts of the circuit to try and figure out what's going wrong may have damaged the ECU. The port for the diagnostics is on the ECU btw. Please keep us updated as it will help someone else in the future

https://www.ebay.co.uk/itm/Honda-Motorcycle-HDS-Pro-Diagnostic-Best-OBD-Tool-For-Fuel-Injected-Motorcycles-/222578745146

I gave you your first like ever on a forum!! Haha

I gave you your first like ever on a forum!! Haha

...shall I not mention I'd already liked his thank you post to me

Correct voltage does not mean it is 'correct' - I'll try and explain:

The voltage is measured using a meter with a very high (high resistance) load and therefore minimal current flow.

The items on your bike (fuel pump, starter relay, etc. need to be fed CURRENT and this can only be done if: a) the voltage is correct AND b) the resistance in the circuit is LOW.

You mention measuring 230 Ohms - Not sure where that was measured but from battery, through ignition switch, ignition relay to earth is OK but NOT OK across the ignition switch, relay contacts, etc.

From the symptoms, I would suspect that the earth return (frame connection) that connects the lead to the battery is 'bad' - Loose and/or corroded (rusty). This will give the intermittent symptoms you describe.

I have a cbr125 06 the two sides from battery with ring terms go to a vacant plug with a cap ?????

9 hours ago, Cbr125 said:

 

I have a cbr125 06 the two sides from battery with ring terms go to a vacant plug with a cap ?????

 

That could be a charging lead.

On 01/11/2022 at 07:42, Mississippi Bullfrog said:

That could be a charging lead.

Or, it could be to attach an ancillary device (heated grips, USB port converter, Sat Nag mount, etc.).

if it is not causing you any issues - leave it where it is.

1 hour ago, Grumpy Old Git said:

if it is not causing you any issues - leave it where it is.

 

This is very wise advice which unfortunately many times I have not followed!!