T-Max charging circuit woes

I've had my current T-Max for some time now and like many (most?) used bikes it came with a few legacy issues of the previous owners (neglect) and the usual litany of shortcut repairs (just one example). Mostly now I'm just coping with the sort of age related things that one expects over time; she is of course nearly 15 years old now. Most of this has been electrical.

My present issue (I believe now solved) harks back to this "event" in early 2019 with a failure of a wire, which was fixed with a rewire of one connector. For one reason or another I ended up not using the bike much (contract out of town) and used it mainly for weekends. However the rise of COVID-19 saw me working from home in 2020 and using the T-Max more (but mainly for trips into the main town 35km away as I live in a small village).

Now all of this took place over a lengthy period not least because of a toe surgery for some arthritis and hurting my back (meaning I couldn't ride),a lengthy period of rain and parts supply delays.

20:20 Hindsight

Now if I could have my time again I'd have done a more thorough rework of the wires involved and that my friend is why I am writing this to you. Rather than just replace that one connector on the RIGHT HAND SIDE which has 3 white,(which BTW is from the stator and thus carries a higher voltage and more power) a red and a black (so a 5 wire plug) you need to look at the origin of those 3 white wires on THE LEFT HAND SIDE OF THE BIKE; because all that happened was that the next weak link in the chain (on the other end of that wire) simply became the next fail point.

Keep in mind when reading this that the failure by me to fix properly the entire wire run from where the plug comes out of the engine (providing 3 phase power to the regulator rectifier) was the cascade event for all this. Again, that is on the LEFT HAND SIDE.

You have been warned.

The Saga of Failure Begins

The problem with bikes is that they have too much plastic over the things you need to inspect (sort of divorcing people from wanting to inspect as well as fostering a whole generation of useless narcissists who are incapable of fixing anything), had the motorcycle had a simple volt meter on the dash (or even a proper "charging" indicator) I may have picked this up earlier, but alas all I got was an occasional flash of the engine light.

So riding home one afternoon of September 2020 (yes, last year) the bike suddenly stopped, it stank and when I pulled over smoke was billowing from under the seat. Lifting the seat I saw it was coming from the battery ... pulled the tool kit (from where its conveniently placed under the seat) and disconnected the terminals, and extracted the battery

which was smoking and puring sulphur fumes everywhere. I'm fucking glad that this was the 2004-07 model not the newer one because the battery is right up there at the frong under all that tupperware and it would have essentially destroyed all the electrics on the bike (including the engine management system). The battery had been totally fried.

So first order of the day was to try to get it home ... that just took a friendly discussion with the local car mechanic and we trailered it home. 

Step 1

With the scooter home I then needed to replace the battery (in order to attempt to start it). With that in place I tried to start it and as soon as I turned the key I knew that there was a deeper problem because the familiar whir of the fuel pump was not there ... a quick test of the fuel pump (with 12V) showed it to be working (but I'd ordered a spare while testing this) and so I thought about it for a while. 

The other choice was that the engine immobiliser was somehow faulty (and it was somehow) as this works by disabling the fuel pump ... I tweaked to this by the fact that the LED on the dash was not doing its thing, but I could not remember what "normal" was.

Step 2

I pulled out the manual and looked over the circuit and could see that there was. I observed that there was an immobiliser sub circuit:

However I soon discovered that this "system" was deeply tied into the Engine Management System (including fuel injection) and from Yamaha the price for replacement was nearly AU$2000 (because it came with keys, a Key Recogniser and an entire new EMS

Faarrrkkk ... 

Some exploration of the idea revealed that the engine immobiliser circuit seemed to be an integral part of what (the frequenlty fucking idiots) in the trade refer to as "the antennae" circuit (which is found under the key unit, obscured partially by the bulkhead) I wondered if this could be bypased.

a discussion with a mate (also electrically inclined) suggested this possibility

which seemed like the obvious next step for a small outlay.

Success was had and the fuel pump turned when key moved to "ON" and the engine started and ran.

Great stuff so now I could move on to working out why the battery was stuffed.

Step 3

With the engine now running I could test the charging. Wow ... the rectifier was working but the regulator part was broken because at idle it was charging a bit much but at 5000RPM it was totally over charging ... 27V

So, this is now the third new mode of failure I've seen on the regulator rectifier.

Step 4

I called to make an order for another regulator rectifier from Yamaha to find that the price has gone up, in Australia it was now over AU$300 and special order, so I hit up eBay again and bought an aftermarket one from some seller and in due course it arrived and I fitted it and it worked!

The plug however was so fucked (recall the previous butchery) that I decided to re-terminate all the connections with just simple spade connectors.

I used a fully insulated one for the center white (three phase) one because 3 insulated ones wouldn't fit together and they were fully isolated from the others by them being insulated.

I looked around at the LHS of the bike where the 3 white wires from the stator plug into the "harness" and they looked a bit gammy but I measured around the joint and it was all passing through the right voltages. I thought about cutting that plug out and just soldering them together but as I'd started to re-assemble the bike dismissed the idea.

THIS IS WHERE ITS IMPORTANT TO NOTE: if something looks like its failing then it probably is, and probably accelerating in its mode of failure.

So I reassembled the bike and wondered briefly should I go back and fix the rest of the wires. Seemed a hassle so put I back together and began riding it.

...

This period lasted until last weekend when it stood me up again. This time however the failure was more graceful this time.

Next Failure

on the way back home from town (35km away) the speedo and tacho fell to nothing and the LCD display blanked ... the motor was continuing to run normally ... I thought "what is wrong this time" quickly followed by "will it make it home" ...

Nope it shutdown and I coasted to a halt.

Another phone call to a friend with a trailer and bring it back home again to put up on the slab and to another autopsy.

While waiting for my friend (about half an hour) I thought I'd just try the key and see if it started. The lights came on and the fuel pump whirr sounded. I noted on the dash that the ODO was now showing. 46 where the ODO was previously. I looked this up (of course I have the manual on my fucking phone) and it declared it to be: "Power supply to the fuel injection system is not normal".

With high hopes I turned the key and it the starter motor had a go at it but gave up.

Step 5

On getting home I charged the battery and while waiting I pulled the regulator rectifier off and measured the 3 AC phase pins with my diode testing setting on my Multimeter. It was rooted (the usual Open Circuit mode of failure this time), so I've ordered a new one (and I'm still waiting for that to arrive)

Wondering about things I started it and measured the AC phases ... well ... one phase was down AND the plug now looked pretty manky over on the other side (left) of the bike 

It was clear that two wires of the 3 were giving reduced current (probably much worse under load) and so I cut the plug off for a closer look.

overall the wires looked good a little way out (so it was all caused by the erosion of quality of termination over time) and so I decided to simply cut the plug out and solder the wires directly together.

each phase is:

• soldered together
• has a layer of black heat shrink
• a further layer of red heat shrink
• wrapped in an amount of electrical tape
• cable tied together (for support and to prevent the electrical tape unravelling)

that should see it last a while.

Step 6

when the new regulator arrives I'll fit it and complete this post. So Ta Ta for now

Conclusion

no matter what, don't just stop with the first bad joint you find in electrical work especially when there is higher power and voltages involved. My old philosophy is this:

where there's one there's two...
where there's two there's more!

Happy Scooting