My charging system is a puzzle. Need some plain talk.

[deejais]

Mar 7, 2021 9:07:02 GMT -5 GrumpyUnk said:

Looked at the manual and schematic. The 'testing' section is rather specific about some things

As always, great information and I appreciate your long reply.   I ordered a new main relay, going on my gut and simple elimination, as that is the only simple part that is a variable to me at this point.  My hope goes up a little bit because the starter relay was also bad.  My fingers are crossed.

Afterward, my only recourse (like you said) will be the ECM.   I've learned it's the bane of people who own this model (and maybe all Hondas), because it's such a pricey part, and Honda insists on building the regulator/rectifier inside.

And it struck me that the service manual tests on the ECM were all to determine either continuity or battery voltage with the engine off.  I don't think I can measure output with the engine running, because any time I disconnect ANY WIRES, the engine shuts off.  Exception:  I can disconnect the 3-pin main (red) leads from the stator while it's running, but pulling apart the 6-pin connector shuts it down.   I imagine disconnecting the 26-pin ECM connector while running would also shut it down.

Curious your thoughts on this and again, thanks.    BTW, you're in the ATL area?  I'm in Acworth.

[ThaiGyro]

Not loads of fun with that particular Alternator/Starter franken-Honda setup. I see your other problem in testing:

www.bikebandit.com/oem-parts/detail/honda/30400-get-672/b2267017?m=151295&sch=93233

Yikes! $300 on sale for the ECU seems high for a scooter, but does many jobs like any bike. Maybe find a used one...or under a hundred for a Chine clone.

I am with GrumpyUnk...find/build a system that separates the starter from the alternator. Bummer.

[deejais]

Mar 7, 2021 13:17:37 GMT -5 ThaiGyro said:

I am with GrumpyUnk...find/build a system that separates the starter from the alternator. Bummer.

Yes, I'm learning a lot about how other manufacturers do their own thing.   But mostly, I've learned to avoid Honda Metropolitans, even if they're free.   haha.

[GrumpyUnk]

BikeBANDIT ... Hmmm. Not exactly highway robbery, but doing some digging with a Dremel tool to un-cover the components might be a worthwhile investment of time. Many times 'potted' components can be worked free of their covering goo/plastic/??? and exposed to determing condition, part number and for replacement(after more surgery).
The parts generally failing would be electrolytic capacitors, diodes(rectifiers) and possibly transistors/SCRs.
If you can determine the part number of the original, and find it shorted or open, de-soldering and soldering in a replacement part may fix the problem. I have done it on some things.
There is a web site for small engines that have electronic ignition components(clinton/eska for a few names) that are 'buried', but can be successfully excavated and parts wired in, in place or externally.
To make clear, the stator and rotor(flywheel) should generate voltage across the three windings, one at a time, to ground if the flywheel is rotated. Dunno how many rpm, but it should push out some volts without being connected otherwise when the flywheel spins. Plain old magnetic field and conductor whirring through lines of force(magnetic) pushes/pulls electrons through the conductor.
I suspect the diodes are charred inside the ECM. Glad I did not bite on one of the Metros for sale on FB marketplace. Sure seemed to be a nice machine when introduced. Honda 'reliability'(from weather, potted to death) and fun performance with EFI. Did NOT know of the starter/alternator combo. They used a starter/generator combo on some older Outdoor Power Equipment engines. NOT many. I think not such a good idea back then, and maybe it should work better with electronic controls. Honda did make a hybrid fastback that would give power assist from a battery pack, and re-charge the pack when coasting to a stop or partially applying brakes... Tested on the Honda Metropolitan??? ,... mebbe
tom

Added:  REad here:

advrider.com/f/threads/honda-metropolitan-easy-to-work-on.954560/

 You may want to reconsider spending more time... ??

[ThaiGyro]

I have not had one of my own. I do believe that My Thai friends built/rebuilt and love these Metro's. Good mechanical stuff! Not all have the funkified alternator/starter. That is why I/we think there is merit in looking to divide and conquer that issue.

I also believe that is it worth the time to look. Sometimes "backdating" can be better than "updating". I think that engine design lived a long existence.

[deejais]

Mar 8, 2021 11:43:29 GMT -5 GrumpyUnk said:

but doing some digging with a Dremel tool to un-cover the components might be a worthwhile investment of time.

Oof, that is out of my depth.  How I wish I could just bypass this ECM altogether, like maybe introduce an aftermarket regulator/rectifier from the stator to the battery.   But everything I've read leads me to think this is a no-go.

By the way, I went through the entire CHARGING SYSTEM TROUBLESHOOTING process in the service manual, and this is the one fault that presented itself.  Of course, it suggests replacing the most expensive and mysterious part:





And curiously, I still get zero volts AC from the three stator wires while engine is running (grounding the meter lead to the neg. battery post).   I can only deduce that's because the ECM is bad.  The stator wires are not connected to the ECM when I test them, but a six-wire bundle from the stator *IS* connected.

Now, to find a replacement ECM.  My normal supplier has none and tells me Honda has discontinued it.   My head hurts.

[FrankenMech]

There are solvents that will dissolve some potting compounds, unfortunately they will also take off component markings and will even eat the printed circuit with time.

[jbjhillbilly]

You can buy used working ECM for the Met for less than $100. And just so you know, the ECM model has to match the harness (learned it the hard way).

You can also try resetting the ECM -

[deejais]

Mar 9, 2021 23:19:42 GMT -5 jbjhillbilly said:

You can buy used working ECM for the Met for less than $100. And just so you know, 

Yeah, I went on the (very helpful) Facebook groups and found a used ECM that the seller assures me is good.  It'll be here in a couple of days.   If that doesn't work...I will officially declare myself out of ideas.

And thanks for the tip about resetting the ECM.  Have done that many times, but it's one of those simple things that I'm sure is often overlooked.

Wish me luck with the "new" ECM.

[ThaiGyro]

deejais...good for you!

I am old and experienced enough to know:

That I can take bad shit, work in some home shit, test it with bat shit and make it work...like shit. Then? Start again. Kind of fun!

[deejais]

UPDATE -- and good news! I solved my charging system problem today. I'm now generating 14.5v at higher RPM's as should be happening. I am tremendously relieved.

In doing so, I identified a Honda OEM part number that is incorrect, and it was the source of my problem. As I was going through the charging system troubleshooting process AGAIN, I pulled the starter relay and the main relay to test them. Upon closer examination, I realized that they were installed in the wrong sockets! The starter relay was in the main relay socket and vice versa. The two relays fit in each others sockets, but they are NOT the same unit! One has 5 pins and the other 4.

Looking at the OEM parts diagram, they are 100% incorrectly labeled. The main relay (38501-GEE-712) is labeled as the starter relay, and the starter relay (38520-GEE-711) is labeled as the main relay.

What sucks is that I bought a used ECM from a guy, because all my tests were failing (due to the mixed-up relays) and the only thing left to do was replace the ECM. I guess I now have a backup ECM.

I wonder who at Honda I can contact to report the bad OEM numbers? This will screw up the next guy who has my same charging system problem.

[FrankenMech]

Fill the unused relay socket pin location with silicone or epoxy to prevent future swaps.

Honda probably does not care about old systems.

[ThaiGyro]

My guess is that even if a "Honda" part...assuming the original packaging, numbering and such, that these were farmed out to the Easterly neighbors. Hard to say.