RXV Brake Problems and Encoder Signals

[Billybob16]

Hi, I'm new here and new to working on Golf Cars at a local cart shop. what a great tool this is...Thank You!

I'm working on an RXV that is applying the brake when you are trying to accelerate, some times to the point that the cart will not move, wheels chatter and stop. The encoder was replaced 4 months ago and now the cart has came back with the same problem.

I decided to look at the encoder output with a scope to see what the signal is looking like, see pictures below . I'm wondering if anyone can tell me if this is correct, what it should look like and how it changes during acceleration. Below is what I see.

First off it is not a perfect square wave and is noisy especially during acceleration with steps developing with more RPM..see pictures 1) No rotation 2) slow 3) faster. The signal gets worse the faster you go. I think this is the problem, either encoder is bad again or noise is being introduced some place, bad connection. I tried running a new ground directly but no change, 5V looks okay.

Any advise from experienced cart techs? What should this signal look like, both outputs look basically the same. Does this signal come from the Danaher controller? Any areas that I should be looking at?

[cgtech]

Basically, you have to be watching as it messes up, not while it's working fine on jackstands. That's why I like the little $20 Chinese portable scope kits that run on a 9v battery.

[cgtech]

The wire harness just "up wind" of the sensor is likely polluted with corrosion. Peel back the black wire loom & look for salty-appearance or swelled wires. You can usually clean it up with baking soda & water, but the problem inevitably returns later. Also, be sure to here is as much slack as possible I the encoder wires, ezgo is well known for routing those wires too tight.

[nickdalzell1]

Scope I got from Amazon (runs on a 9V power supply) has saved me the extra work of removing a few good encoders when the throttle sensor under the floor was the real culprit!

[Billybob16]

Thanks for the input! After checking further, I decided to look at the brake signal. It was clean, a clean and consistent never changing wave form no mater the speed on jack stands, that is making me think I may have 2 or 3 problems. 1) the brake its self or installation of. 2) encoder or the installation of the Encoder 3) as suggested wiring harness/connection/throttle.

Still checking

Thanks

[Billybob16]

Just wanted to followup on final solution to this problem.

The brake was the problem, replaced and cart ran fine. The brake signal is a constant square wave.

Thanks for the help!!

[cgtech]

Originally Posted by Billybob16

Just wanted to followup on final solution to this problem.

The brake was the problem, replaced and cart ran fine. The brake signal is a variable 0-5v signal.

Thanks for the help!!

There, I fixed it for you.

The motor brake is a pwm signal to "chop" the voltage down to the controllers desired setting.