Motor controller disassembly, Gem e2, T6

I had to remove the motor controller from a Polaris Gem e2. For the benefit of those faced with the same challenge, here are some pictures of how it went for me.

  1. Switch all the power off.
  2. Switch all the power off.

The Gem e2 was built in 2014. Here is the label on the roof of the compartment.


I believe that the controller is T6 type.

Here is the vehicle with the bonnet and motor removed.

The controller appears to be oriented left-right (seemingly unlike the controller in the video I found at GEM Car Controller Removal for 2005 & New GEM Cars - YouTube).
I marked up the cables with masking tape labels before removing them to help identify where they needed to go back.

The controller is held into the vehicle by six nuts that engage with six studs coming from below.

The ones at positions 4, 5 & 6 are really tricky to get to. I was just able to get a 10mm socket over them, but there isn’t much room between the nuts and the controller case.
Be aware that there are eyelets for electrical cables at positions 5 & 6.

With the nuts removed and the cables disconnected, the controller is easily lifted out of the vehicle and we can move onto the bench.

To remove the plastic case from the motor controller I had to

  1. Remove short Torx screws from positions 1 to 8.
  2. Remove bolts at positions A1, A2 , POS and NEG. Note that the bolt at position A1 is shorter than the others.
  3. Remove screws A, B, C, D holding the 23-way connector

The case still took a bit of coaxing by inserting a flatblade screwdriver between the case and the base. I suspect it would have been even more difficult if the gasket seal had still been in place, but I suspect that was long gone.
The field connectors slide through their rubber grommets.

With the plastic lid removed, the top PCB is exposed.

To flip over the top PCB, remove screws 1 to 6. Also unscrew the green and yellow wire from the current sensor on the A1 bracket.

It might help to remove the two screws holding the A1 bracket in place (arrowed above)

With a bit of jiggling it should now be possible slide the top PCB up the field connectors to fold it out to reveal the bottom PCB (here covered by the paper insulator).

Beneath the paper insulator is the bottom PCB.

There are a total of six screws fixing this PCB to the heatsinks.
Screws A, B & C are crosshead and came out with a bit of coaxing.
Screws 1,2 & 3 require a flatblade screwdriver and I was unable to remove these. In the end the screws broke off in the holes. I’m not sure how I deal with this when I need to re-assemble it.

The screws clamping the MOSFETs to the heatsinks (circled further above) also need to be loosened and then the bottom PCB can be lifted clear of the heatsinks.

On this board, you can now see the charring on the right hand side which is the result of a failed component. That may or may not have been due to the large amount of liquid residue (assumed to be water) found inside the case. I’ll pick up that story in the original thread.