Vida CEM swapping

[3oh6]

Teensy will most likely crack it over OBD.

Thanks for your reply Vitaly.

So, I bought a Teensy 4.0 and other components (3.3>5v LLS and 2 x MCP2515 CAN modules) to make the cracker and have assembled it exactly at this:- https://github.com/mdapoz/volvo-cem-cra ... ematic.png. The only thing I have changed is to add a voltage regulator that takes the 12v on pin ODB2 pin 16 down to 5v to power the Teensy and CAN modules (I've cut the trace to separate USB 5v >Vin on the Teensy).

Should this work with the latest code? Because I'm not getting any CAN communication (I'm getting ''Unknown CEM part number 0. Don't know what to do. Resetting all ECUs." in the serial monitor).

Just for information, I'm trying to get the CEM pin from a 2008 C30 in the car over OBD2. Cheers

[vtl]

Teensy will most likely crack it over OBD.

Thanks for your reply Vitaly.

So, I bought a Teensy 4.0 and other components (3.3>5v LLS and 2 x MCP2515 CAN modules) to make the cracker and have assembled it exactly at this:- https://github.com/mdapoz/volvo-cem-cra ... ematic.png.

Ugh... Mark's repo was cloned long ago, that's not "the official" repo. Since then we've migrated both the hw and sw to Teensy's built-in CAN controllers and SN65HVD230 CAN transceivers. Pretty much any 3.3v CAN transceiver will work, some folks run it on Bosch CF160.

That's the primary repo: https://github.com/vtl/volvo-cem-cracker

[3oh6]

Teensy will most likely crack it over OBD.

Thanks for your reply Vitaly.

So, I bought a Teensy 4.0 and other components (3.3>5v LLS and 2 x MCP2515 CAN modules) to make the cracker and have assembled it exactly at this:- https://github.com/mdapoz/volvo-cem-cra ... ematic.png.

Ugh... Mark's repo was cloned long ago, that's not "the official" repo. Since then we've migrated both the hw and sw to Teensy's built-in CAN controllers and SN65HVD230 CAN transceivers. Pretty much any 3.3v CAN transceiver will work, some folks run it on Bosch CF160.

That's the primary repo: https://github.com/vtl/volvo-cem-cracker

Ah ok cheers, no worries, I'll try and order some SN65HVD230's and try again

[rkam]

It is so annoying waiting for parts.

Searching my house yesterday for some Seagate 7200.10 head tool, I found no less than three Teensy 4.x.
The first was bought back in 2020, and I was planning on testing the CEM cracker.
That never happened, since I had already read my CEM with soldering wires to the PCB.
But It looks like I have been meaning to a couple of times more.

Then I found a Can tranceiver on my desk, and thought it might be time to test the cracker.

At first I got the same message as you 3oh6.
This was because I had the High and Low can wires connected opposite of how they should.

Correctly connected the cracking took 30 minutes.

Looking at Mark's code, it appears to be defined for MCP2515 without Low Speed CAN.
#undef HAS_CAN_LS /* CEM is in the car, both LS and HS CAN-buses need to go into programming mode */

While you are waiting for parts, you might recheck the wiring, and settings.

[vtl]

Mark is playing with a tiny 2-row LCD display for the cracker, btw. We may have a support for that soon, so the whole rig can be used w/o a laptop running terminal.

[dikidera]

In standard OBD PIDS, we have STFT and LTFT. In Volvo DHA I cannot find what STFT is, specifically as a percentage for Denso. I can log afr, but I cannot log STFT as I do not know if it's even stored somewhere(I guess it is).

Is it simply the percentage of fuel required to get to 14.7 or is it more complex than that?

I am trying to track down an issue, if it is caused by insufficient fuel, clogged cat or maybe the ETM.

[3oh6]

It is so annoying waiting for parts.

Searching my house yesterday for some Seagate 7200.10 head tool, I found no less than three Teensy 4.x.
The first was bought back in 2020, and I was planning on testing the CEM cracker.
That never happened, since I had already read my CEM with soldering wires to the PCB.
But It looks like I have been meaning to a couple of times more.

Then I found a Can tranceiver on my desk, and thought it might be time to test the cracker.

At first I got the same message as you 3oh6.
This was because I had the High and Low can wires connected opposite of how they should.

Correctly connected the cracking took 30 minutes.

Looking at Mark's code, it appears to be defined for MCP2515 without Low Speed CAN.
#undef HAS_CAN_LS /* CEM is in the car, both LS and HS CAN-buses need to go into programming mode */

While you are waiting for parts, you might recheck the wiring, and settings.

Thanks for the info! So those new transceivers actually came super fast, I rewired it all as per the latest schematic on vtl's repo and I got my pin in around 25 mins!

So my question now, is there a way to read the CEM flash in the car over OBD on a P1? I tried T5Luke's CEM flash reader with my Dice, but it just displays tons of errors (I'm guessing it only works on the P2 CEM's?). It does accept my pin though

[3oh6]

Mark is playing with a tiny 2-row LCD display for the cracker, btw. We may have a support for that soon, so the whole rig can be used w/o a laptop running terminal.

Oh cool, sounds interesting! So would it be like a ModUnlock type device?

[RickHaleParker]

Is it simply the percentage of fuel required to get to 14.7 or is it more complex than that?

LTFT and STFT are percentages which represent the adjustment to the fuel injector pulse width .

Total Fuel Trim is the sum of LTFT and STFT. Total Fuel Trim = LTFT + STFT

Examples:
A LTFT of 10% and a STFT of -5% : 10% + - 5% = 5%.
A LTFT of -7% and a STFT of 5% : -7% + 5% = -2%.

[vtl]

Oh cool, sounds interesting! So would it be like a ModUnlock type device?

Let's rephrase it according to truth: modunlock is a stolen cracker code, with a display.