Ok I’m stumped. I’ve replaced ALL wire harnesses relays and the fuse box. There’s all new wires to and from the battery, new alternator and belts and I can’t get this thing to charge. Here’s the weird part. If I disconnect the battery using the switch, then the alt puts out over 14V as soon as I turn on the battery switch it stops charging?!? Any ideas?
Start by having the new alternator bench tested, if that passes, then try a different battery (believe it or not) and also look for any possible miswiring. Errors can cascade when you shotgun repairs and it's sometimes hard to know if you're still fighting the original problem, or an entirely new one.
Where are you measuring voltage from? something like this, take a step back, think about the whole picture, go through and measure the voltage one step at a time, you'll find the issue. You need excite voltage to the alternator, and connection to the battery, it's not rocket science.
Going by ASV’s wiring schematic, there’s no wire from the harness to the W spot on the back of the alternator which I believe is the excite spot for a 3 wire alt?
The new alt produces plenty of power when not connected to the battery, so I’m now thinking that the new battery I have might have a shorted cell? As soon as I connect the battery to the charging system, the alt stops charging. I’ve even tried using jumper cables off my trucks battery “with truck off” and the ASV alt was charging the trucks battery. I’ll replace the battery Monday and hopefully that sorts it out.
"W" is Wild three phase for driving the tachometer, doesn't matter to the alternator. D+ should have the same voltage as B+ when the ignition is on. A battery with a shorted cell will just overcharge the good cells, it shouldn't suck so many amps that it keeps the alternator under 13.5V. does your battery hold a charge? leave it overnight and is it still 12.5V or more the next day? does it start the engine by itself?
Back to my suggestion to have the parts house bench test the "new" alternator, producing voltage no load means less than nothing. When you can get 14.5 volts at the rated amperage load, then you know it's good.
I’ll check this with a meter. I’ve been having to charge the battery externally to start and run the ASV for short tasks around the farm. Not sure if this would matter but, one feature this RC100 has I’ve never seen before is a battery cut off switch wired between the battery ground and main harness so that you can disconnect the battery. The replacement factory harness is “plug and play” but the ignition dashboard is always powered even with the key off? I found that odd? Not sure if that’s any clues to help figure this out, but thought I’d mention it. I’ll check D+ and B+ for the same voltage with the ignition on and report back.
Sounds like there might be two issues, one is the alternator charging, the other is the wiring of the machine up to the alternator including the disconnect switch. If I had to bet, if you figure out the second, the first will be fixed also. Until you get it figured out, remove the ground cable at the battery in addition to the disconnect switch. It's awfully hard to track down wiring issues AFTER they burn.
Put a meter on it today. With ignition on B+ was 11.55 and D+ was 2.5 I confirmed 11.55 is the battery voltage as I need to put the charger back on it.
You have to start with a charged battery for anything to make sense, so charge that up. Then start it and connect B+ to D+ and see what the voltage is then. If that brings it close to 14V, then you have to figure out why you don't get battery voltage at D+ with the ignition on, and you'll need a wiring diagram for that most likely.
I do not know anything about ASV's so I apologize ahead of time if I am stepping out of bounds here. Did you do as lantraxco said? At 11.5 volts I would change the battery. It may or may not charge up but my money says it is sulfated. A bad battery could seriously affect the voltage out of an alternator as well. Most definitely. Just an observation. I think there is some confusion on the OP's side on conditions for measuring these terminals. Does the machine have a charging indicator light? If so then most likely the D+ is providing the ground for the light and therefore a key on engine off reading of 2.5 V would be normal being that you are essentially measuring the ground side of the light. Then with engine running the D+ voltage should be at or very close to the B+ voltage. Again a schematic would be a huge help here. So I would get that battery issue resolved first. Measure the D+ and B+ with the key on engine off. Then start it and measure the 2 again. Then post the results. The "W" terminal is usually for tachometers, and on some systems it is also used for indicator lights that are controlled by some sort of system controller.
Good point. I said the voltage should be the same with the ignition on, that's wrong as MG explained. Putting battery voltage to D+ will either make the alternator charge with 14v, or the alternator is defective. This assumes that you start with a charged battery, that will hold 12.7V or more for several minutes after removing the charger, and start the engine without a jump.
The brand new battery is on the charger and once 100% I’ll test again and report back. Thank you everyone that’s helped out with this so far. I’ve got many mulching and grapple jobs lined up this spring and want to get this 100%
Here’s the results. Ignition on engine off B+ red 12.26V D+ grey 2.6 Engine On. B+ red 12.27V D+ grey 11.65V
Backstory time, I hired a local mechanic to replace all the wire harnesses in this rig. His work is clean and tidy, that being said... Went digging in the overhead console and found three wires not attached to anything. One puts our 12V and one of the other two must be a ground. Here’s a link to the wire diagram, https://drive.google.com/file/d/1i-fYmdw6DQEjyWY6A4nKkuJbMNa4jw-t/view?usp=drivesdk I’m also noticing the hour meter / fuel gauge instrument cluster don’t shut off with the ignition key off? I feel like this is something simple I’m not spotting.
Alternator is bad. Don't ever turn the battery disconnect off with the engine running next time. Wouldn't hurt to try between W and Bat with a test light to see if that gets the voltage up right. I haven't looked at the wiring diagram, but that's a separate issue if you're getting close to 12V at the D+ terminal.
Is there voltage to pin 7 (yellow wire) at the display when you key off?
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.
I’ll be replacing this wee harness as the connections on the back are toast.
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!!!!
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.