Chevy Bolt Motor Control Adventures

[mobythevan]

Hello, first post but this looks like the right place to be.

Some Background on this long and winding road to the Chevy forum on Openinverter.org:
11 years ago I wanted to build an EV conversion so I studied up for several months, purchased an RX8 and the canEV adapter plate. I made my full plan for conversion and the cost came to about $24k with a somewhat small battery capacity. After considering my options I bought a 2014 Chevy Volt and abandoned the idea of electric conversions as too expensive for my budget. In 2020 I traded the Volt for a Bolt that I daily drive. All along I've had the desire for an EV conversion project but can't justify the budget. Since 2000 I have been heavily involved in building car projects and doing EFI swaps with Megasquirt EFI. These have become increasingly complex wiring projects as the cars platforms have become more complex. Along this gasoline inspired path I've had the opportunity to learn Megasquirt 1,2,3 along with Holley Terminator X Max and EFI Live. Add in one more parallel path that my professional career is Electrical Engineering and it starts to make sense that combining project cars with electric motor power really combines all of my interests.

If you stuck around this long or skipped to this section then you can share in my excitement as I found myself at UpullandPay on my brithday (Jan 5th, lol) looking for ICE car parts and my wife says "hey, that's a Chevy Bolt right there". Yeah, my wife goes to the salvage yard. I ended up making 3 trips to grab various modules and pieces from the car. Unfortunately no battery pack, but pretty much everything else. Not sure how the car ended up there, it was not and is still not listed as being on the yard. I am very excited to dig into this, I have been researching like a mad scientist the last 3 weeks to assess the state of the DIY community knowledge and current level of understanding for Chevy Bolt motor and module control. This has lead me all over the place from seeing that HP Tuners is developing an EV computer, to studying GM-Lan and GM-LIN, to looking at professional level tools like Intrepid Vehicle Spy, learning about serial digital gateway modules, Global A and Global B GM platforms, and finally here to the forum to share my lucky find and share what I can learn from it.

Given that I have a 2020 Bolt I daily drive and now I have all the parts from a salvaged 2020 Bolt I am hoping to understand some of the pieces that have been a high interest to the community for swapping and controlling Bolt motors. I'm just getting up to speed so be patient with me.

https://photos.app.goo.gl/XxFFMLuHygufyK4s7
https://photos.app.goo.gl/dfWbLd7aU8vaDCsz7

[P.S.Mangelsdorf]

Welcome! You're in the right place!

I've been interested in the Bolt inverter as well, but it does look like you've got more useful skills than me, and you've got parts on hand, so perhaps I can help on the research side. If you haven't gotten them already, I have reviewed the wiring diagrams and pinouts from the GM service manual, and have screenshots. I need to clean those up/reformat so I can share them. Let me know if you already have them or would like what I have.

Also as you may have seen, control of the charger and DC-DC converter have been worked out (and are working in my build) but we do still need to work out the exact correlation between PWM duty cycle input, and the power drawn by the charger. You may have the tools to investigate that more scientifically than I do.

[mobythevan]

Excellent, I was hoping you would reply. I definitely appreciate the offer to help. I did find the 2017 service manual and have been getting familiar with the schematics and connector end views. Not sure how much I can help but let's find out. I'm having a bit of paralysis because I have 3 major goals and I don't really know enough yet to know if those are proper goals. So trying to pick one and get started.

My naive main goal would be ability to deactivate and spoof enough systems to allow the ECM (are we calling it ECM or PCM on the Bolt?) to control the motor. I do not have the battery so no battery control module. From my first look it seems buying the MPVI3 and using HpTuners to pull the binary is a good start. See if anything overlaps for the ICE E84 computer. I see people have used HpTuners on the E84 on Chevy Spark so that is worth investigating I think. PCM Hammer only showing support to 2007 doesn't look promising. My thinking here is to get VATS removed like I would do for any GM engine swap.

Supporting step is getting hardware that can sniff the GM-LAN and GM-LIN. Not much movement is going to happen until I get these working and capturing data. I realize already the protocols are not simple enough to just record and playback messages. Sometimes that will work and maybe that would be good enough to spoof systems. I doubt it.

Another supporting step is dealing with all things battery and high voltage, but I'm punting on this for now until I can understand more about the system. I need the ECM to get far enough that it would apply power based on the accelerator pedal before high voltage comes into play.

If I'm on the wrong track let me know. Will also catch up on your thread, you may have answered some of this already in your write ups.

[P.S.Mangelsdorf]

Excellent, I was hoping you would reply. I definitely appreciate the offer to help. I did find the 2017 service manual and have been getting familiar with the schematics and connector end views.

One item of caution, at least the version of the service manual I pulled had the wrong pinout for the charge port. Fortunately, I had also pulled the Spark EV pinouts, and those were correct.

I'm having a bit of paralysis because I have 3 major goals and I don't really know enough yet to know if those are proper goals. So trying to pick one and get started.

My naive main goal would be ability to deactivate and spoof enough systems to allow the ECM (are we calling it ECM or PCM on the Bolt?) to control the motor. I do not have the battery so no battery control module. From my first look it seems buying the MPVI3 and using HpTuners to pull the binary is a good start. See if anything overlaps for the ICE E84 computer. I see people have used HpTuners on the E84 on Chevy Spark so that is worth investigating I think. PCM Hammer only showing support to 2007 doesn't look promising. My thinking here is to get VATS removed like I would do for any GM engine swap.

I think it would be great if we can get the Bolt inverter working outside its native environment. You may have seen on Youtube a guy basically transplanted the whole Bolt drive train into a Delorean. I think it would be very useful to be able to use these components without ALL of the Bolt systems.

Ideally, I think, would be full control of just the inverter with the ZombieVerter system. However getting control of the ECM/PCM would also be a huge step forward.

I'm pretty sure that the Bolt is GM's Global A, so it should in theory be easier to get into the system than later Global B cars. Sounds like your approach is a good first step, even if it doesn't work we've learned something. From what I have seen hunting around for parts and data, it appears to me that the Gen 2 Volt, the Bolt, and the Spark EV share a lot of components or at least control approaches, which makes sense for GM. So in theory, cracking one cracks them all. I want to get my hands on a Bolt battery and see if the Volt Gen2 battery CAN messages are the same. That would be nice.

[Tremelune]

Just here to cheer you on! The Bolt is the next "standard" in EV conversion parts...

[P.S.Mangelsdorf]

Just here to cheer you on! The Bolt is the next "standard" in EV conversion parts...

Certainly for us in North America, I agree. They built a whole lot of them.

[mobythevan]

Def appreciate any cheering. Small update:

Ordered the HpTuners MPVI3 to see what it will dump. I want it for my other ICE projects but maybe it will dump something sort of useful, maybe not.

Did a deeper dive on Kess V3, ECM Titanium, WinOLS and several other similar things for binary dumping, writing and reverse engineering.

Bought several ECMs off ebay to have some comparisons that may help reverse engineering, dunno. Got a Spark gas version E84 ECU, got a spark EV E78 ECM, a gen1 Volt E78 ECM and a gen2 Volt ?? ECM. I'm thinking that comparing binaries and having the gas version will help me identify areas I am familiar with from past tuning, help divide and conquer the binary.

Got a quote for ValuCAN4-2EL and Vehicle Spy V3 software, but on the fence about whether I need this. Prob do so I can watch all traffic between battery module and ECM. This is expensive, so is Kess V3 and WinOLS so I am mulling over my budget and what I really need. I think there are plenty of binary tools that are not automotive specific, but not many tools to analyze GMLAN and GMLIN protocol.

I'm still hoping I could end up with ability to delete VATS, possible understand ""torque"" control tables in the ECM and hopefully interface the battery module messages allowing any battery to be used with factory ECM. Of course many safety rails may be over ruled (temperature, etc would be up to driver to manage, in the spirit of DIY). Lofty goals I know, gotta dream big.

[Bratitude]

Have you thought of just doin a can log of the motor bus on your daily bolt?

Not sure if the motor can bus is exposed on the obd port, but u have the parts to make a interception harness so no need to cut anything

[P.S.Mangelsdorf]

Have you thought of just doin a can log of the motor bus on your daily bolt?

Not sure if the motor can bus is exposed on the obd port, but u have the parts to make a interception harness so no need to cut anything

I'll check the wiring diagrams I have and try to upload them sometime early this week.

[mobythevan]

Definitely good idea to snoop the GMLAN networks. I printed and highlighted the network diagram from the 2017 manual to help me get familiar. I did a bit of work this weekend, I'll write up some more detail this week.

[Bratitude]

Definitely good idea to snoop the GMLAN networks.

yeah i dont see the bolt having any vin pairing, and based off the volt stuff i snooped through, i dont see it being overly complicated messages required. maybe some crc and timers. if you can do a can sniff with savvy can, and dump, chances are the forum will have it figured out pretty quick

[mobythevan]

Well I went down what seems to be one dead end path, but it was good to learn. Purchased a usbjtag nt link thinking I could simply pull binaries from the ECM, VICM and PCM. Turns out that the ECM and PCM both have the MPC5676R which is well documented and easy to find the JTAG pins on the boards, but it is a password protected chip. If you look around a little you can find that side band attack can be used to bypass the password which also echoes it out so you have it( and seems to be random unique for each chip, not just one password for all). That doesn't seem worth hobby level swapping so I'm fully moved to CAN bus decoding now. It was interesting though because it taught me about Ghidra and a few other tools.

Right now I have connected the ECM and VICM CAN bus and powered up to dump the list of DTCs from HP Tuner. Its quite a long list, lol. Next step is add the motor control module and put that list up here as its the starting point of what the 3 computers need if we want to swap a bolt motor but use some other battery.

Got a Canable 2.0 and set it up on my shop laptop on the Ubuntu side with Savvy CAN. Connected it and verified it captures logs from the ECM-VICM bus. Have not set up anything to decode GM Lan yet.

[mobythevan]

Started looking around for DBC definitions to decode GM Lan and found something crazy, I suspect other people here are already working with this.

https://github.com/commaai/openpilot

This project controls cars that have the super cruise type of systems(whatever other manufacturers call theirs). Since Chevy Bolt is one of the cars with super cruise it seems like a lot of development has already been put into this in the form of DBC files to interface 2022-2023 Bolt and Bolt EUV through CAN bus. Hoping they overlap closely with 2020 Bolt that I have. Poking around I can see it has several definition files for the powertrain control modules. I see what looks like code for all the battery cells voltages, temperatures, etc. Please chime if if you have more information about the depth of CAN bus definitions in this project. I am working through installing and testing decode of my captures.

Seems like I only want the opendbc and cabana tools for definitions and reverse engineering. They deprecated the standalone cabana so have to install the full openpilot repo which is a bit painful. Had to upgrade ubuntu to 24.04 to start with.

[P.S.Mangelsdorf]

Yeah the work done for the commaai is a nice resource, I haven't dug into it at all but they collect a lot of data on different vehicles.

[mobythevan]

I was able to load the generated global a dbc in cabana last night and it decodes several messages. I still only have ECM and VICM(HPCM2) on the bus. Not as many messages decoded as I hoped, the life of reverse engineering.

[pts211]

I just want to chime in that I'm following this. I've been wanting to make a Willys Jeep EV for years - realized in the last week that the Bolt system might be the fastest (and most affordable) approach. I haven't officially started anything yet, but I'm excited to see someone tackling it exactly how I was thinking as well. I'll certainly chime in if I see a way I might be able to help!

That said, have you had any luck making progress in the last month?

[P.S.Mangelsdorf]

I've been wanting to make a Willys Jeep EV for years - realized in the last week that the Bolt system might be the fastest (and most affordable) approach.

I've thought about this a lot as I have an (extremely rough shape) CJ-3A languishing at my parents' place (600 miles away).

If you're looking for quick and easy, a Leaf stack bolted to the Jeep transmission is going to be the best bet. The Bolt motor is integrated into the transmission/gearbox, so to use it you'd need to find a way to lock the differential, use it in place of the Jeep transfer case, adapt the axle output into drive shafts, and then change the Jeep axle gearing.

Nevertheless, glad to have you aboard, the more the merrier!