Diode energized both sides, but no continuity

[Fairtax4me]

Remove the yellow wire from the solenoid, tape it off so it can’t short to anything.
Now re-check voltage on both solenoid posts. Then check voltage on the yellow wire when it’s not on the solenoid.

What problem are you trying to diagnose?

[sonofagunn]

Thanks fairtax, that was a good idea. I tried it and confirmed that the 48v exists on the yellow wire, it's not coming across the solenoid.

I was under the impression there should be 0v if the pedal is not pressed. Am I wrong about that?

[Fairtax4me]

What cart are you working on?
And again, what problem are you having?

[sonofagunn]

Originally Posted by Fairtax4me

What cart are you working on?
And again, what problem are you having?

It's a 2005 DS IQ.

There is another thread describing the problems with my cart, but the primary problem is that, when I first back the cart out of my garage, it won't move at first (reverse buzzer is buzzing). Repeated mashings of the pedal will finally get the cart to jerkily back out. Then, the cart works mostly fine after it's "warmed up."

I've read lots of threads of similar problems on here and the common theme is people replacing parts that don't fix it. The other thread finally landed on the conclusion that my motor is bad, but I don't want to buy another one or have it rebuilt and end up with a faster cart that still has this same problem w/ cold reverse. So I wanted to test the solenoid first, and came upon this unexpected result.

I really appreciate the help.

[Fairtax4me]

Sounds like motor to me. These motors are really easy to pull apart to check the brushes. I've had a couple of those IQ motors burn them right down to almost nothing and score the commutator pretty bad. The last one was doing a shudder/jerk right at takeoff for a few weeks. It never showed any problem with power until right before it quit working altogether.

Can't say for certain if there should be voltage on the yellow wire, but the fact that it works OK after you get the cart to move a bit makes me think brushes are shot.

[sonofagunn]

Originally Posted by Fairtax4me

Sounds like motor to me. These motors are really easy to pull apart to check the brushes. I've had a couple of those IQ motors burn them right down to almost nothing and score the commutator pretty bad. The last one was doing a shudder/jerk right at takeoff for a few weeks. It never showed any problem with power until right before it quit working altogether.

Can't say for certain if there should be voltage on the yellow wire, but the fact that it works OK after you get the cart to move a bit makes me think brushes are shot.

scottyb's instructions imply there should not be any voltage on that wire until the pedal is depressed - see the bottom of http://www.cartsunlimited.net/solenoids.html

I just have a suspicion I have 2 problems and after replacing or rebuilding the motor I'm still going to be left with the more annoying problem. Most similar problems I have read about here were fixed by replacing the MCOR or solenoid.

[Sergio]

That comment refers to the Solenoid post the yellow cable is connected to, not the yellow cable coming from the controller.

You are measuring the charge in the controller capacitors, leave that cable disconnected long enough and the voltage will go down slowly on the disconnected cable as the capacitors discharge.

[sonofagunn]

Originally Posted by Sergio

That comment refers to the Solenoid post the yellow cable is connected to, not the yellow cable coming from the controller.

You are measuring the charge in the controller capacitors, leave that cable disconnected long enough and the voltage will go down slowly on the disconnected cable as the capacitors discharge.

When I disconnected the yellow cable the solenoid passed the test, so I am pretty sure the solenoid is good. I'm still not sure if the yellow wire is supposed to have 48v on it before the pedal is pressed - none of the solenoid testing instructions I've seen mention removing that wire before testing.

[Sergio]

You are overthinking this, the solenoid is just a big switch.


What happens to the disconnected cable is not relevant in any test

[sonofagunn]

Maybe I am overthinking it, but I did finally determine the solenoid is working ok after removing the yellow wire.

I was just caught off guard by the 48.0v on the negative side where I was expecting to read 0v. I still don't know if it's expected for the controller to have 48.0v on the yellow wire (and therefore the negative side of the solenoid) before the pedal is pressed. Every thread I've read says the negative side should have no power without the pedal being pressed so it seems like something I should investigate.