VW contactor box reverse engineering

Browsing eBay, I chanced upon a VW Golf GTE contactor box, I've had 2 of these before, but butchered them to take control of the contactors directly, but this time I wanted to know more. My main aim is to reuse the isolation monitoring circuitry for extra safety, but baby steps.

The easiest thing would be getting control of the contactors first, as it's pretty obvious when this is happening, they click closed.

So this thing is still holding some secrets, but so far I've got the voltage message decoded and control of the contactors. This thing also reports current, though I'm not sure what message that is on, I'm not sure how to activate the isolation monitoring and if it does any sort of tracking of energy in and out, yet.

https://github.com/jamiejones85/VW-GTE-ContactorBox is the current example code for interacting with the box.

UPDATE

I've got it cracked, I can now ask it to perform an isolation test and interoperate the result. Very happy with this. Now to 3D print a smaller enclosure and install in the car.

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