GEM 2000 won't move

This is a GEM 2000 e825 long utility with SurePower retrofit, new DeltaQ charger and Trojan lead-acid batteries. It was running, then I took out the 4 under-seat batteries to clean and reinforce their compartment. That led to a problem with the wires to handbrake switch - fixed that. But then I found a condition where it would only move a foot or two, forward or reverse. The Polaris mobile tech advised, get a new motor. I got a new motor, put it in, made no difference.
When I key on and release brake, the contactor ‘clunks’ there’s a humming sound but no power forward or reverse, no change in that sound when I press the accelerator, and no error messages. So I’ve been working thru the diagnostics in the service manual. Battery voltage is OK. the SurePower tests are all OK. The handbrake switch and accelerator start switch are OK.
The accelerator potentiometer test gives a [U]reverse[/U] result from what the service manual says; resistance I measured between pins 7 & 9 of connector MH20 is 5K ohms with pedal up, almost 0 ohms with pedal down. I don’t know what to make of that - I never messed with those wires.
Any ideas what I could try next, before the last resort of calling in the tech? Like, how can I be sure the motor controller is working?

You can have the motor controller tested by mailing it. RFF and a few others offer this service. Have you checked out the DC converter?


Well I got the tech in and he had enough parts to replace and check the functioning of ALL major components. Motor and controller and accelerator pedal were all fine. After a lot of frustrating work we found a fault in the main wiring harness, between the accelerator and pins 7 or 9 of the controller. This was enough to make the motor run fast, slow or not at all, depending how the wire was bent.
Hope this info may be useful to someone in future!

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I despise electrical gremlins. So time consuming to track them down. Glad to hear your getting it back on the road again!