ASV RC100 not charging

Greybrook said:

Well the mystery continues. Had the second new alternator bench tested today and it’s working perfectly. Put back in, connect B+ and D+ start up and no charge... So then I run a jumper wire from D+ to 12V and still nothing. I disconnect the B+ wire start up and touch D+ to 12V and it’s producing power!?! So I trace the B+ back to the right side of the brand new fuse panel and wire harnesses and all looks ok? Stumped again.

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B+ must be connected to the battery at all times that the engine is running. So your alternator functioned once you touched D+ to B+. Why didn't it when it had voltage back in post #15?

So the main 60 and 80 amp fuses are good? According to the schematic the battery is connected to the alternator through these fuses.

Ignore my last post, I MIS READ which wires you had connected. MG and I suspect there's something wrong with the wiring. Actually there has to be something wrong with the wiring if what you've said is correct. Just a matter of finding it. I don't want to search through that wiring diagram that MG sent me any more than I have to. Two things that stood out though, D+ is fed through a resistor AND a diode. Test the voltage at D+ with the ignition on but D+ disconnected from the alternator, it should be the same as the battery volts to tell you the resistor and diode are fine.

I'd run a jumper straight from the battery to the B+ and D+ terminals and start up the engine, if that doesn't charge at 14v, then find out what is wrong there. Test the voltage on both sides of your disconnect, alternator case to battery negative terminal, every voltage you can think to find where the voltage isn't that it should be.

Once the alternator works with a jumper on the machine, then you can figure out where the wiring is messed up. That's my strategy anyway.

Here’s a follow up to this post. The problem was!?! A “OEM” alternator that wasn’t OEM. Vendor shipped first Alt to me, install new alt and no charge. Return Alt and vendor sends me another “OEM” alt and that one also doesn’t charge. Eat the cost of that vendors Alt and purchase an alt directly from Perkins. Install and works perfectly. Lesson learned and o longer doing business with said vendor.

Those dam parts guys!!!!

Greybrook said:

Here’s a follow up to this post. The problem was!?! A “OEM” alternator that wasn’t OEM. Vendor shipped first Alt to me, install new alt and no charge. Return Alt and vendor sends me another “OEM” alt and that one also doesn’t charge. Eat the cost of that vendors Alt and purchase an alt directly from Perkins. Install and works perfectly. Lesson learned and o longer doing business with said vendor.

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Damn. Probably something as simple as one machine/brand being spec'd for an internal diode feeding from B+ to excitation and one that has an external jumper with the diode in the harness.

Sorry to revive an old thread but by any chance did you put a meter on your new correct alternator post D+ to see if you still had voltage on it with ignition OFF and no wires hooked to it except the B post?
I'm having similar issues and have the same constant voltage to my hour meter. I have 3v on my D+ terminal and 12.5v on my B+ terminal. Both go to 12v with ignition on.
I bought this last week from deceased owner so I don't have any history of it. New Engine was half installed and I finished it and ran into this. I've checked all wiring and everything looks good according to the schematic. Scratching my head

I talked with ASV techs a LOT whilst trying to figure out my issues. they let me know the fuel meter is always on, take a look at the overhead wiring to be sure you're not accidentally tapped into that circuit.

My big issue with my charging system was purchasing an alternator from Vine and Branch being told it's OEM. I went through two of them before realizing they were selling me aftermarket cheap junk with the prices jacked up.

Purchased one from Perkins and it worked as soon as I bolted it on.