Idling Stop works intermittently

[prasannar2009]

Hello everyone,

The automatic start/stop system in my 2015 PCX 125 works sometimes. So, I understand that after starting off it takes a while for it to come up once the vehicle is 'warm enough'. But mine never seems to start working. But let's say after about 10-15 minutes of riding, if I switch off the vehicle myself and start it again, voila! The start/stop LED turns on, and it works! But let's say after about 2-3 times of automatic start/stop, the LED (and the system) turns off again - until I manually turn off the engine and start again. What do you think is the cause of this? Is this normal? Something to do with battery voltage, or some loose wires? Thanks!

[Oldie]

I'd guess that your battery is on the way out. Test it at rest with a meter, say 24 hours after your last ride, and it should hopefully show at least 12.6v. If it's below 12.4v then it's probably time to buy a new one.

[Jge64]

Yup, battery.....Most of the idle stop systems will not engage if the battery is not at least 12.0 to 12.2.....

[prasannar2009]

Thanks! I'll check the voltage tonight. But if it does turn up that the battery voltage is less than 12.4V or so, do you think the battery needs replacing, or could I make it better by charging it fully? Thanks!

[Oldie]

Buy a new one. They don't last forever and it's a relatively small cost for peace of mind.

[iceman]

Honda have a graph in the UK service manual for LED versions onwards, which states and shows a stepped curve whereby the idle-stop stops working if the ECU feels the battery is not up to the task of repeated start/stops and surge current - it's by design as in pre LED models idle stop killed batteries if over-used and the battery was failing.

[raito]

This is exactly same as mine. But now even 10 minutes of riding and switching engine off and on rarely gets the idling stop back on. I thought it was the battery too, but checked my battery was 12.66V under no load. So I don't know.

[Oldie]

This is exactly same as mine. But now even 10 minutes of riding and switching engine off and on rarely gets the idling stop back on. I thought it was the battery too, but checked my battery was 12.66V under no load. So I don't know.

My next step would be to test the battery with the engine running (at low and medium rpm's) and report the results.

[RikudoPCX]

I had something similar, the battery was fine but the ECU was on the fritz. Eventually, the bike wouldn't start at all. Luckily it happened whilst I was under warranty so called the dealer and they came picked it up and had it working the next day.

[aphid]

I stopped using the idle start on my 2013 model PCX after about 6 months. I began having problems starting the bike and it seemed quite clear my battery was very run down, which made no sense.
To cut a long story short, I read about reported issues with the idle start running down the battery, and since my daily round trip to work and back was only 3 miles or so, the battery clearly wasn’t having much opportunity to recharge. After that I stopped using the idle start, and haven’t had any issues since then.

[iceman]

Pre 2014 models, idle-stop could easily run the battery down, LED models onwards ECU's have a graph, not a straight line, that disables idle-stop should it believe the battery is being stressed too much - the graph response has dips and rises, so battery voltage alone is not the decider unless it gets to low.