Troubleshooting 1206MX for 42V Cart with no Solenoid Power

[jazman]

Hi,

Owner of a '89 EZGO Marathon gas cart here, but this question is about a 42V Western cart, which I believe is just an EZGO in disguise.

A short version of the back story is we were visiting the in-laws and they had borrowed this cart for us to use. We were warned that the controller was prone to failure and not to go full speed or put the pedal to the floor or else it would blow. I suppose it could make sense for a motor that perhaps has a little more friction than when new and thus draws more current. I was leery of touching it from the start but relented and all was well for a few days over probably 20 miles. Then, on the day we were flying back north I was just pulling it into the driveway. I actually wasn't even on the pedal and not going very fast turning into the driveway when it let out a series of beeps and went dead. I don't know how many beeps unfortunately, but when I went into diagnostic mode I only got 4 beeps indicating freedom mode.

I then did a lot of research into the controller and confirmed it was a 1206MX along with a 36V solenoid. I then looked at the troubleshooting document from FSIP and started probing voltages. Everything checked out until I got to pin 9 where I got 0 voltage (all the voltages through the reed switch, tow/run, and F/R check out).

Originally looking at this on my phone while at the cart I thought it meant one of the internal diodes was blown, but now that I can see the diagram on a normal screen it looks like there should be a dead short internally between pin 3 and pin 9. This diagram is probably simplified a bit so maybe that is not the case?

Has anyone run into a similar result? Does it map with the idea of the motor drawing too much current? It doesn't add up to me given I was not on the pedal when it happened. If the failure is in this area it would seem more like some type of surge on the primary side of the solenoid. I couldn't test the motor resistance as I did not have an accurate meter.

Any insights would be appreciated. I'm probably going to get stuck with the bill for this, which is a little frustrating given that I followed the instructions I was given. I should have followed my instinct and not touched the cart in the first place!

[BobBoyce]

The 1206MX was not a great controller to begin with. Operating a 36V controller on 42V is just hoping it does not fail.

Pin 2 and Pin 3 should each have a diode to Pin 9 internally. If you have B+ at Pin 1 but nothing at Pin 2 or Pin 3 when selecting F or R, then the FNR switch could have failed. If you have B+ at Pin 2 when in R, or B+ at Pin 3 when in F, but nothing at Pin 9, then the internal diode(s) have failed. You can wire in a pair of external diodes, one from Pin 2 to Pin 9 and the other from Pin 3 to Pin 9.