Sorry for the late update folks. Been down with a stomach bug. But hey , its been 5 years so whats another week. Anyway, before running any real power through the inverter I decided to scope the gate-source waveforms just in case. High sides looked fie but all THREE lowsides showed this sort of a weird ground bounce effect of the other 2 low sides switching. Did dome probing around and narrowed into the "56Ohm" source resistors. Hmmm. Guess what? They are not 56 Ohms on the OEM board.... rather 0.56Ohms!!!
Got the right ones ordered but still feeling very happy about progress on this 1st prototype.
Re: Tesla Model 3 Rear Drive Unit Hacking
Posted: Mon May 26, 2025 10:44 am
by johu
Nicely caught in time!
Re: Tesla Model 3 Rear Drive Unit Hacking
Posted: Wed May 28, 2025 1:18 pm
by Jack Bauer
Just a model 3 inverter with an OI board running a model 3 motor.... nothing interesting:)
Re: Tesla Model 3 Rear Drive Unit Hacking
Posted: Wed May 28, 2025 5:17 pm
by Jack Bauer
For those interested current V2 board schematic. Not finalised yet but has corrections from V1 and now all component values and types populated. Basically the current board minus the bodges:)
Re: Tesla Model 3 Rear Drive Unit Hacking
Posted: Thu May 29, 2025 4:58 pm
by Jack Bauer
Re: Tesla Model 3 Rear Drive Unit Hacking
Posted: Fri Jun 06, 2025 3:50 pm
by Beatbuzzer
Do you have any thoughts about the sort of pyrofuse, placed in the newer rear inverters? Would you transfer it to your design or remove it? I mean, it simply goes away by removing the pcb Only attached with two screws in the frame of the hall sensor.
Seems its not only placed in plaid, but also in Model 3 long range and standard range from 2022. My rear inverter is a 3D5 from 2022 and has it.
I'm in a little research at the moment. There is an additional circuit on the right side of the pcb. Connection of the squib is wired in parallel to the two bigger 499R resistors.
Re: Tesla Model 3 Rear Drive Unit Hacking
Posted: Mon Jun 23, 2025 12:11 pm
by davefiddes
Managed to get my JTAG connection working again so I can make some improvements to the Tesla M3 gate driver support:
So far I've included the various fixes from above and a new version of the gate driver class. This has a correctness fix in the initialisation verification process. It also pipelines SPI requests when polling the status which makes it substantially more efficient. Both changes more accurately reflect the behaviour of the original Tesla firmware.
I'm planning on parsing out the gate driver failures and reporting them as spot values shortly.
Re: Tesla Model 3 Rear Drive Unit Hacking
Posted: Tue Jun 24, 2025 6:26 am
by Jack Bauer
Thats excellent Dave. Thanks. I've been cleaning up the board and getting ready to order V2. By the time it arrives I'll have the Volvo V50 test mule in the barn and ready for full up tests.
Re: Tesla Model 3 Rear Drive Unit Hacking
Posted: Sun Jun 29, 2025 2:34 pm
by davefiddes
Meanwhile in Open Source development... I have finished making the updates to the Tesla M3 gate driver support code to pull out the detailed fault information:
@crasbe was absolutely correct in their analysis as to the order in which replies are received from the gate driver SPI chain. My new code now pulls out the details of any fault on a chip by chip basis. If you are having a good day it looks like this:
It's probably bolting the door after the horse has departed but hopefully it'll be helpful should anything go wrong. Some of the errors it can report I don't think will ever be reported (ASC and SENSE) but better to have the decoding in there than be left in the dark if something weird happens.
Thanks Dave. I'll get this in the board. Should have the V50 ready for tests this week. So far I once accidently (and once on purpose) shorted two phases with a screwdriver during low voltage bench tests. Trips off the inverter and restarts no problem.