Strange RXV Issue - for the geeks

[konakid]

So - my main cart broke down. No problem, that is why I have an RXV for my backup. I jumped in, it had been sitting for a few months, and been charged regularly. It ran perfectly for about 45 minutes.

Then I stopped and it wouldn't move. I thought it might be the notorious brake issue. However, in tow it moved easily. But in regular run mode it just stuttered a bit, and didn't move an inch, and stopped doing anything altogether. It did make a not nice sound twice when trying repeatedly to get it to go. Then it would give a hint of a stutter, but no movement.

THEN - I thought of pushing on the pedal while manually pushing at same time to assure brake was releasing when pedal was depressed - as it seemed it was. And it took off, almost catching my sandal on the pedal and dragging me into the side of the house. Now it starts and stops as it always did.

Is it possible there is some "flat spot" on the motor - that if stopped in that exact spot it won't get going again??? I stopped on perfectly flat ground which usually isn't the case. That is sure what it felt like.

Any other theories???

[konakid]

Just did it again. This time I put the wife in it and pushed from behind as she pressed on the pedal. For the first foot nothing, then I told her to pump it and I pushed another foot or two and it took off.

It doesn't sound like it's the pedal switch since I hear the brake release, but I had to push 2-3 feet before it kicked in and then ran like a champ.

[BobBoyce]

Originally Posted by konakid

Just did it again. This time I put the wife in it and pushed from behind as she pressed on the pedal. For the first foot nothing, then I told her to pump it and I pushed another foot or two and it took off.

It doesn't sound like it's the pedal switch since I hear the brake release, but I had to push 2-3 feet before it kicked in and then ran like a champ.

If the brake is good, you should not be able to push it at all! Sounds like you may need a motor brake. There is no normal configuration of run/tow/EM brake bypass that would allow you to push it then drive it without reconfiguring.

[konakid]

Thanks Bob - I guess I did not explain correctly.

I put it in tow (key on) and I can push it - out of tow brake engages and I cannot - until I push on the pedal (key on), then I hear the brake release, as it should. But the motor stutters or does nothing.

So I confirm the brake has actually released when foot is on pedal since I can push it while my foot is on pedal. I take foot off pedal for a second or two and the brake engages as it should (and I cannot push). And it stops me as it should when coming to a stop.

So, when it won't move on its own I push it a couple of feet while my foot was still on pedal (key on), and it kicked in and ran fine. It stopped fine, and started up again fine, until it repeated the same scenario several stop/starts later.

BUT - this morning it would not move again, so I turned key on/off f/r several times (key controls f/r), and then on about the 10th try I slowly depressed pedal and it started running without pushing - all other times it was the push that got it moving. I can't seem to repeat anything that would point to a definite cause.

[BobBoyce]

Originally Posted by konakid

Thanks Bob - I guess I did not explain correctly.

I put it in tow (key on) and I can push it - out of tow brake engages and I cannot - until I push on the pedal (key on), then I hear the brake release, as it should. But the motor stutters or does nothing.

So I confirm the brake has actually released when foot is on pedal since I can push it while my foot is on pedal. I take foot off pedal for a second or two and the brake engages as it should (and I cannot push). And it stops me as it should when coming to a stop.

So, when it won't move on its own I push it a couple of feet while my foot was still on pedal (key on), and it kicked in and ran fine. It stopped fine, and started up again fine, until it repeated the same scenario several stop/starts later.

BUT - this morning it would not move again, so I turned key on/off f/r several times (key controls f/r), and then on about the 10th try I slowly depressed pedal and it started running without pushing - all other times it was the push that got it moving. I can't seem to repeat anything that would point to a definite cause.

Ok, that makes sense now. Pushing it should have no bearing upon the motor spin, as there are no brushes to seat onto a commutator better. If it were an issue with the motor speed encoder or the motor temperature sensor, it would still move, but very slowly.

However, if there were a low battery pack voltage issue causing a loss of torque, that could be an indicator. Pushing it might cause some regeneration, raising pack voltage a bit. RXV controllers are extremely sensitive to voltage drop at the main pack. What year is your RXV?

[konakid]

Thanks Bob - I'm getting some more clues. Pack voltage should be good, because when it runs - it runs fast uphill, just like always. I think this is a 2010. But batteries are 3 yrs old - maintained and a new good charger.

This info should be a smoking gun:
I seem to hear a "second" click when turned on and then it runs. Only one when it won't. But brake always releases when pedal is pushed. After it is running, I can stop and start it all I want and the brake works as it should, allowing me to slow and stop and engaging after a second or two to keep it from rolling.

However, if I turn the key off, or wait over 10-15 minutes, it starts acting up again when turned back on - not moving and stuttering sometimes. I can turn the key off/on many times and no-go. And then one time I hear a second click/slunk, and it works and stays working until turned off again completely - by key or by waiting.

This last time I jerked the cart back and forth as I turned the key on. With the rattling, I couldn't hear if that second click happened, but it worked.

So, it seems as if there is something to do with the brake that activates when the key is turned on. And jerking it around does something. But not to be confused with the click sound of brake release that happens when the pedal is then depressed - that is not the issue. In other words, the motor isn't getting full power and the brake is keeping it from moving because it is engaged. But something seems to be keeping it from getting full power.

Hard to explain, but I tried. I might add that a new brake was installed a year ago, and there has been very little use of the cart. I did take it for a long fast spin just now, when it was running, and no smell or anything weird at all. Stopped and started multiple times. But turned it off and back on, and problem is repeating.

[cgtech]

Sounds like a wiring problem, or more likely encoder problem. The wire for the newer style encoder (at axle flange end of motor) is stretched too tightly, and wrecks the tiny wires on the encoders short wire to the plug.

[konakid]

Originally Posted by cgtech

Sounds like a wiring problem, or more likely encoder problem. The wire for the newer style encoder (at axle flange end of motor) is stretched too tightly, and wrecks the tiny wires on the encoders short wire to the plug.

Thanks CG - but now what? I've no idea what an encoder is. Is it a replaceable part? To check that out I suppose I have to remove the second seat like I had to do to replace the brake? Will I see it and be able to service/repair.

I don't suppose there is anyway to be more certain before going this path? If I jerked it back and forth and got it working, then let you drive it, start and stop and brake as often as you liked, you would think it was running perfectly, as long as you didn't turn the key off. Then if you turned the key off and immediately back on it wouldn't run until I "jerk-started" it again.

So, as long as the "circuitry" remains energized, it stays working just fine. But when the current is removed, then turned right back on it fails. Maybe if I knew what an encoder was (or does), that would make more sense to me.

But when I do that (turn off, then right back on) it feels/sounds as if it just getting a trickle of power. Why would that be? Is that encoder related?

[BobBoyce]

First click would be solenoid engaging, second click is the motor brake disengaging. If the solenoid is going bad at the contacts, that could be the issue. The solenoid used on the early RXV is not as good as the later one.

[konakid]

Originally Posted by BobBoyce

First click would be solenoid engaging, second click is the motor brake disengaging. If the solenoid is going bad at the contacts, that could be the issue. The solenoid used on the early RXV is not as good as the later one.

Bob, I was hoping) that might be the problem. But I thought that when I turned the key on the solenoid clicked (which it does), but the brake stayed engaged until I pressed on the pedal - as it does now. Maybe I don't correctly understand the sequence of events.

But I don't think by just turning the key on that the cart would start rolling downhill - correct?