2020 e4, I am experiencing intermittent acceleration. GEM is fully charged, both traction and Aux and no fault codes. The user states that when driving normally, he heard a loud “pop” somewhere he couldn’t say where it came from. Since that moment the car started stuttering forward and the car got progressively and haltingly slow. When in Forward and Reverse, the intermittent acceleration is present. I replaced the Acceleration Pedal w a new part and even used a pedal from another GEM and the problem still persists exactly the same. So the pedal is ruled out. When I say intermittent, when pressing down on the pedal suddenly ‘all at once’, the car will not move, however, if I ‘baby’ the pedal pressure like slowly and haltingly the car does move (both F and R separately) but still sporadic and not smooth acceleration, and sometimes not at all. So I was thinking it sounds like more of a mechanical nature like a Relay contacts failing or wiring or switch vs some component with containing software (VCM/Controller).
Has anyone come across this issue and found a solution? Can anyone recommend any possibilities on how to troubleshoot this issue?
Inwo, that is a good idea. I just came across a thread you had last summer with clubcmc regarding a similar problem. I suppose there is no way to test the encoder to see if it is malfunctioning as it operates under the ‘Hall effect’ which needs to monitor something rotating/moving…or is there something I can test before just part replacement and hope (…and change. )?
Similar issue with a ford think. The cart was bucking when accelerating. I drained the gear box (transfer case)oil and saw brass colored shavings. First tried disconnecting the speed sensor and that lit up the cluster but no difference in performance. Still bucking on acceleration. Thinking the bucking could have caused the gear box failure. Replaced the solenoid but with a used one so can’t eliminate that a bad solenoid was causing the bucking. Any of this sound similar or offer a possible solution for a gem?
The GEM eM1400 came out in 2014 with an AC motor (48V). eM’s were unique in their design, look like single bench seat Polaris Rangers from that same era, RWD, 4 wheel independent suspension, 4 wheel vented disc brakes, electronics, motor and gearbox really only fit them (and maybe the polaris electric ranger) all steel frame, heavy as hell.
The “Classic” body GEM (bubble front windshield) was DC drive 72V until they were discontinued in 2016 ish I think
New body style (current - has the flatter windshield more square body ) GEMs have been AC motors & 48V since release in 2016 ish.
Toyota was not involved in any way as far as I know.
I was going for dirty comms or sticky brushes first.
But I didn’t want to hijack the OP’s AC thread with DC solutions.
Future readers are going to be so confused.
Inwo,
You are correct in that the encoder is much more than a speed sensor, I did a little bit of research on it to inform myself. Anywho…I exchanged the encoder with another working encoder from another e4 we have at the retirement community and the problem still remains and the suspected encoder that I took out of the problematic GEM works on the e4…so it is not the encoder.
After troubleshooting this problem further, I would like to restate what the problem I’m having is because I might not have been as precise in stating it before. As the GEM was driving normal on a flat surface (no excessive torque demand), the driver states he heard a lot ‘pop’ somewhere but can’t identify where it came from and it slowed to a stop. Everything seems to be working correctly (instr cluster/charging/accessories/no fault codes/etc) w the exception of driving/movement. While the front end on stands, key on, emerg brake off and press on the accelerator the front tires starts to turn less than a full revolution and disengages…almost as if attempting to go into ‘limp’ mode but it can’t be that because the wheels stop. Now if the pedal remains pressed down after the disengagement and the wheels stop, w/in a minutes time I can hear the contractor click and the wheels starts its turn once again but suddenly disengages/stops…rinse and repeat.
I have ruled out the following either through exchanging them with working parts from a working GEM or through direct testing individually (off the GEM):
all of the fuses and relays in the fuse box / accelerator pedal / contactor-relay / full battery charge (traction & Aux) / gear selection switch / parking brake switch / encoder / U,V,W continuity / motor temp sensor 1kohm / DC/DC relay & converter … all working.
I’m inclined to point my finger at the Motor Controller, not necessarily being totally blown but rather something internal not functioning completely, maybe the loud ‘pop’ was a MOSFET blowing (??). I believe I’ve eliminated those components peripheral to the Controller, VCM and BMC. Is there a procedure to test the motor controller? In past dealings w golf cart Curtis controllers, they could be diagnosed fairly easy but they weren’t as complicated as this SEVCON gen4.
I did take measurements from the pins on the Controller and BMC, but without being 100% sure what should be nominal vs outside of range, I don’t know if they are operating as they should.
any suggestions will be greatly appreciated. thank you Paul
Swapping controller is pretty easy.
Byron is right, don’t probe pins from the face. It will stretch the sockets and create gremlins.
Does car have the same symptoms with encoder disconnected?
That is how a car runs with it unplugged. Remote possibility that encoder wheel is damaged from a pop in the motor. You can see it turn though the hole.
If controller is bad, look for a used one from one of the guys doing a sevcon swap speed mod.
Oem price is obscene.
Ps.
Dont worry about swapping controllers. There are slight differences in programming by motor size and model, but it’s connected as a dumb controller. All of the drive functions are from vcm.
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