Dead Cart - Precharge Failure and No Solenoid clicking or back up alarm

[Kolassus]

Hello all. Looking for some advice. I was driving my cart the other day and it was running perfect. In the middle of the driving, I lost all power. Zero throttle, no solenoid clicking, and even the back up alarm doesn't sound now when I put the lever in reverse.

Battery pack is fully charged. When I plug my PC into the Alltrax controller, the controller is seeing the throttle position, registers full power, but I get a "Shutdown" and "Precharge Failure" alarm on the monitor screen.

My question is where do I start to troubleshoot? Should I start at the solenoid? Is this a solenoid failure or a resistor on the solenoid failure? My cart details should be in my signature. Thank you.

[Fairtax4me]

If you're still within the two year warranty, Call Alltrax.
If not, it's new controller time.

[Kolassus]

So you think the controller is bad altogether? It couldn't be just a bad solenoid or a back resistor coil?

[Fairtax4me]

That's pretty much it.
Do you have an SR or XCT controller?

[Kolassus]

Sr 500

[Kolassus]

After doing some diagnostics, I found that I am getting pack voltage across the two small terminals on the solenoid when I press the pedal and zero voltage across the large terminals. I also don’t here the click. Does this point to the solenoid? If the magnet isn’t being engaged, then the drive current cannot get to the motor, right?

[97ccds-custom]

According to the SR manual from Alltrax:

Pre-charge Failure:
B+ voltage and KSI voltage differ by more than 5v. Stuck solenoid

Maybe a loose connection on the keyswitch and/or throttle or the keyswitch is bad? Have you tried to measure the voltage going off the wires from the throttle that go to the controller to compare to the B+ on the solenoid?

Call Alltrax support. They are awesome and helped me in a few minutes.

I had a partial dead cart issue with my Alltrax SR 48500 showing up as "Low Throttle Input Overrange". Alltrax support was great they had me run a few tests using the software and like adjusting the throttle to USB and controlling it from the toolkit and then determined what the issue was. Ultimately they had me create a ring terminal jumper to run from the solenoid right to the battery main negative instead of J1-Black.
https://buggiesgonewild.com/showthread.php?p=1891106

[Fairtax4me]

Originally Posted by Kolassus

After doing some diagnostics, I found that I am getting pack voltage across the two small terminals on the solenoid when I press the pedal and zero voltage across the large terminals. I also don’t here the click. Does this point to the solenoid? If the magnet isn’t being engaged, then the drive current cannot get to the motor, right?

Right, so you are getting pack voltage on BOTH small terminals at the solenoid, correct?

The Key switch provides input power to the throttle switch, and then the throttle switch sends power to the solenoid when you press the throttle. So if you have pack voltage at both small terminals on the solenoid, it shows that the controller is not allowing the solenoid circuit to be grounded, and the solenoid will not click.

With Key Off,
You should have pack voltage at Both large posts on the solenoid. Keep your meter black lead on the B- terminal on the controller. Red meter lead on the B+ side of the solenoid should be the same as pack voltage, and then on the controller side it should be about 1-2v lower than pack voltage. SO if your pack voltage if 50.9, you should have something like 48-49v on the controller side of the solenoid. If so this shows the pre-charge resistor is functioning, and the controller is faulty. If you do not have pack voltage on either side of the solenoid you have a bad battery cable or poor connection to the solenoid.

[Kolassus]

I have t had a chance to get back to the cart yet to verify, but the tech Alltrax told me to wire the negative side (black wire) from the small terminal in the solenoid directly to B- rather than the J1-cup. However, i don’t have a black wire on the small side of the terminal. The only wire that comes from the small side of the negative solenoid is a yellow wire that goes directly to the OBC. I have the OBC bypassed since I use the Lester 2 onboard charger. Should I connect this yellow wire to B-? I read somewhere that a faulty OBC could cause a solenoid lock out and this would be a way to bypass it? Does that sound like an option?

[Fairtax4me]

Yes, If your yellow solenoid wire goes to the OBC you should cut that off the OBC connector and run it to the B- on the controller. That will at least get the solenoid to operate since it will then have the correct negative path.
It may not solve the errors in the controller, but it should at least click on/off once that change is made.