Solenoid Continuity Question Please

[Mooncarter]

[BobBoyce]

Originally Posted by konakid

Ok - the new solenoid came in late today and I was in a hurry to confirm that was the problem - so I didn't test, I just immediately hooked it up. AND YES, IT RUNS NOW.

I had half the rear end dismantled to get to it - cussing the Cushman design team the whole time - but when putting things back together, I did see that there is an easier way to replace it if I ever have to again. I would have to remove some body "cowling," but now that the rivets are out, I'll replace with some plastic nuts and bolts for easier removal next time around.

So, I learned a lot from everyone - thanks a million. But there is still something I don't completely understand. That is, I have a 72v AC cart, and the solenoid is rated for 48v DC. And it looks as if it is being supplied with 57v+ DC - and this is how it was set up from the factory/dealer.

I guess the main contacts can conduct whatever voltage is in the main power circuit, and all the solenoid needs to do is close those contacts - and that comes from the 57v. But, I'm wondering if this is why the solenoid failed in the first place. Is this going to be the weak point of this vehicle?

And one other thing I noticed is that the 52 error code still continues to flash when in F or R whether the key is on or off. But it goes away when in N. And I am pretty sure it always did this - I just never paid much attention to it since it did it from day one.

I wish I had an expert on this cart to bounce a few questions off of. The "warranty" guy I called came out and although he was nice enough, I felt as if I had to bring him up to speed on things as simple as DC and AC motors - and proved to him his multimeter was defective - and this was at $129/hr.

Good thing I only had him look at my 48v AC RXV - while I waited for the solenoid to arrive for the Cushman. And he's the one who gave me the defective used solenoid to try, claiming it was good. But he didn't know very much about the bearing encoder that appears to be the problem with the RXV. But that's another story, under another topic, that I may revisit here soon.

In closing - thanks again to everyone. Maybe this island needs a good freelance golf cart repairman. At this rate, I'm starting to gain some confidence. And at $100/hr. I could undercut the competition

As cgtech hinted, don't trust the 57V reading you are getting on a Digital VoltMeter. Digital meters will vary in their readings when you are trying to read something with a frequency. This is because the meter takes "samples" of what they are reading. The rate of samples taken vs the signal pulse rate of what they are reading is what affects accuracy of the reading. This is why calibrations and specifications of meters are rated at a specific frequency or list of frequencies, usually 1 Khz or 10 Khz. Rarely does the meters' sample rate exactly match or greatly exceed the sources pulse rate. Digital meters are only perfectly accurate when reading a DC voltage. Analog meters are best for reading signals that have a pulse rate, because the mass of the meter movement itself averages out the reading. I bought a New Old Stock 1960s era Simpson analog meter to use for precision measurements on research projects where digital meters will give false readings due to pulsed signals.

A digital meter also has a higher input impedance, therefore will read a higher voltage than what a lower impedance coil will experience. Voltage is not what pulls in the solenoid coil. The controller monitors the CURRENT through the coil, and PWMs the average voltage up until it reaches the programmed target average current. That target current is adjustable by setting the Main Coil PWM value with an OEM programmer. To add complexity, a current cutback value will reduce the current to avoid heating damage to the solenoid coil.

[yurtle]

I always believed that analog meters would give a fairly accurate reading on PWM, as the meter movement is a coil, as is the solenoid's coil, and even the cart's motor.

I miss my old Simpson.

[JohnnieB]

Originally Posted by yurtle

I always believed that analog meters would give a fairly accurate reading on PWM, as the meter movement is a coil, as is the solenoid's coil, and even the cart's motor.

I miss my old Simpson.

In addition to the electrical properties of the coil, there are the mechanical properties of the movement that dampen the pointer's response to PWM and irregular wave shapes. The moveable coil and its core have mass to accelerate as well as the pointer and there are some hairsprings in the mechanical mix also.

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Ditto on missing a Simpson 260, but a few years ago SWMBO (She Who Must Be Obeyed) bought an inexpensive analog multi-meter with a good battery test feature for disposable batteries and its VOM scales have been adequate for the occasions I've needed an analog meter rather than a DMM. Of course, if I break it I'll be sleeping in the garage with the golf cart.

[mjroman20]

Originally Posted by konakid

And one other thing I noticed is that the 52 error code still continues to flash when in F or R whether the key is on or off. But it goes away when in N. And I am pretty sure it always did this - I just never paid much attention to it since it did it from day one.

The one thing that drives me nuts about these controllers is the versatility with he fault flags. There is a Polaris vehicle I think it was that uses one of these. It has a "fault code" that simply means the vehicle is NOT in park. The drive is not inhibited in anyway, no fault info shows up on the handset. It just blinks a 50s range code. When I finally found the manual - it literally said "parking brake disengaged"

I had once programmed a VCL code that produced a code every Tuesday that cut the speed in half just to prove a point.

[cgtech]

Sounds fun, like automatically rolling down the power windows when the automatic wipers detect rain!

[aldrichd]

Originally Posted by BobBoyce

Warning! Complex answer to a simple question. I'm an engineer, so I tend to view things in a more complex manner than most people. I will attempt to limit my response, and to frame it in a way thay you may be able to understand.

Solenoid coils are not a simple resistance. Since they are technically an inductor (coil of wire) that creates a magnetic field in response to applied current, it is more complex than simply measuring continuity.

A multimeter should measure simple resistance of the coil, ie about 330 ohms. However, a multimeter in continuity mode is usually "looking" for a value of less than 200 ohms as having continuity, and a value of more than 200 ohms as being "open", ie no continuity. So a simple DMM continuity test with most digital multimeters will not be a reliable test for a 48 volt solenoid coil. In this case, you would use the resistance scale, ie 2,000 ohm (2K ohm) scale and measure the DC resistance of the coil. On the 2K scale, a 330 ohm solenoid coil would likely read as around 0.330 which is 0.330 K (Kilo-ohms).

Purely resistive testing does not guarantee that a solenoid is good. There can be damage to the coil or coil form caused by heating that prevents the metal core from pulling into the hole through the center of the coil form, preventing the solenoid from actuating, or damage to the contacts or contact mounts, preventing a high current contact from being made. It is entirely possible to read a contact closure on a high impedance multimeter, yet the contact may not carry high current due to excessive resistance.

I know you are looking for a simple answer, but you need to know why the answer may not always be so simple.

I hope this helps.

I have a Club Car Sw80-1035P 48V solenoid that doesn't click with the key on and the accelerator pressed. I removed the solenoid and measured resistance across the small terminals and show 169 ohms. There is also no continuity shown when testing with my multi-meter. When power is applied to the cart, it shows 48V on both big terminals with the resister removed. Is this solenoid toast or should I be looking for a different issue with my cart?