Alltrax precharge failure

[tsmith_co]

So, I ran my cart earlier today just fine. Parked. Came back 3 hours later and reversed out of the garage. Put into forward and pressed pedal. Solenoid clicks but no go.

Looked at controller (sr48500) and it’s giving the blink code for pre-charge failure.

Unsure what to check. Everything is new (less than a month) and has been working great.

[handtools]

Check the precharge resistor on the solenoid, you can remove it to see if the cart will run.

[JohnnieB]

The precharge failure error occurs when the voltage between the controller's B- terminal and B+ terminal differs by more than 5V from the voltage between the controller's B- terminal and KSI termial (Red push-on jack) ---- Or stuck contacts in the solenoid.

[tsmith_co]

I’ll check voltages. How can I test the resistor?

[JohnnieB]

Originally Posted by tsmith_co

I’ll check voltages. How can I test the resistor?

Controller B- terminal to the solenoid's controller side large terminal should be about 0.5V up to about 5.0V less that the solenoid's battery side large terminal before the solenoid clicks and both ought to be the same voltage after solenoid clicks.

[tsmith_co]

Originally Posted by JohnnieB

Controller B- terminal to the solenoid's controller side large terminal should be about 0.5V up to about 5.0V less that the solenoid's battery side large terminal before the solenoid clicks and both ought to be the same voltage after solenoid clicks.

Ok. So B- to controller side large is 48.1v (batts are currently 50.8v)
I press the pedal and the solenoid clicks. Voltage jumps to 50ish Volta and then immediately drops to 40v (on the B- to controller side of solenoid)
If I just Barry touch the pedal to just get the click, the voltage is right around 50. Pushing it slightly more drops it to the 40v. (Think 2-3%)
In fact, just holding the pedal right after the click is no error code until I push the pedal a little farther. I had slight forward motion briefly with one test. Can’t duplicate. (Edit - can duplicate. Held just after click for about 20 sec, slower pressed pedal and moved. Hit or miss on getting it to happen again

Is the solenoid bad, or is it the resistor or the diode?

[JohnnieB]

Voltage at controller's B+ terminal is dropping when amps start to flow, but battery pack voltage (as seen at KSI terminal) is not dropping a similar amount.

Might be bad solenoid contacts, or it might be a bad cable or connection between solenoid's battery side large terminal and the battery pack's main positive terminal.

Connect the voltmeter from controller's B- terminal to the solenoid's battery side larger terminal. Does voltage there drop like is does on the controller side large terminal?

If it doesn't, the solenoid contacts are bad.
If it does, the cable or connections between the solenoid and battery pack is bad.

Pictures of solenoid terminals and battery pack main terminals would be helpful.

[tsmith_co]

Will check!

I’m betting voltage doesn’t drop. That being said, for kicks I gave the solenoid a “tap tap” (even though it was clicking). It started working 100% of the time.

All cables etc are new also, and tight. I’m not familiar with the insides of a solenoid to know if it’s partially working?

[JohnnieB]

Sounds like you narrowed it down to the solenoid using the tried and true "Give it a kick" method.

What make/model solenoid.

Some of them are position sensitive.

Some of them have exposed contacts and trash can get between them.

[Joel1833]

I’m having the same error message, can’t even get the solenoid to click. New solenoid, bench tested OK. B- to B+ vs KSI is 1.3V in neutral. When in FWD, B- to B+ is 2.6V (total), whereas B- to KSI is 50V (48V system.) Resistor is warm. Depress pedal, no click. Any ideas? Worth noting I left cart out in rain, and some water seeped in on the controller. Didn’t seem to significant though.