Vida CEM swapping

Post by **vtl** » 15 Mar 2026, 18:41

lookforjoe wrote: 15 Mar 2026, 18:37 Came here via GThub - trying to figure out why Volvo-CEM-Cracker is not working on my 2012 C30T5 - trying top extract the PIN.

I can't find any directions on making changes to the script, if adding a part number is what is required

Anyone on here have experience with this?

Remove this line https://github.com/vtl/volvo-cem-cracke ... er.ino#L14

lookforjoe · Post by **lookforjoe** » 16 Mar 2026, 08:52

To continue, after reading one of the posts on here, I rechecked the pinout and continuity on my board & ODBII port, everything matched the schematic.

(EDIT - just saw your response) I also removed the line of code regarding part number check, and still got the same error

I'll drop the CEM, and check that my PN is on the list

Post by **vtl** » 16 Mar 2026, 09:44

Part number 0 means CEM was not able to see commands from Teensy.

"Putting all ECUs into programming mode" - did you car died after that? No lights, no nothing.

lookforjoe · Post by **lookforjoe** » 16 Mar 2026, 19:10

No, it started & runs just fine.

I had to modify the ODBII port as it didn't have all the wires in the correct locations. Perhaps it is somehow defective, even though the pins all check out with a multi-meter.

Also, my CEM is a listed number

Post by **vtl** » 16 Mar 2026, 19:19

lookforjoe wrote: 16 Mar 2026, 19:10 No, it started & runs just fine.

It has to go full dead. Relays click and it's dead.

lookforjoe · Post by **lookforjoe** » 16 Mar 2026, 19:29

vtl wrote: 16 Mar 2026, 19:19
lookforjoe wrote: 16 Mar 2026, 19:10 No, it started & runs just fine.
It has to go full dead. Relays click and it's dead.

I didn't try in-between - it said re-settting all ECU's ? It ran fine after

I didn't add the 10K resistors on the ground circuits - another user said these boards don't need them with the diodes in place. Would that make a difference?

Post by **vtl** » 17 Mar 2026, 07:15

lookforjoe wrote: 16 Mar 2026, 19:29 I didn't add the 10K resistors on the ground circuits - another user said these boards don't need them with the diodes in place. Would that make a difference?

Which diodes?

I see 10K on your transceiver boards.

Does you car shuts off when Teensy says about programming mode?

lookforjoe · Post by **lookforjoe** » 17 Mar 2026, 20:01

vtl wrote: 17 Mar 2026, 07:15
lookforjoe wrote: 16 Mar 2026, 19:29 I didn't add the 10K resistors on the ground circuits - another user said these boards don't need them with the diodes in place. Would that make a difference?
Which diodes?

I see 10K on your transceiver boards.

Does you car shuts off when Teensy says about programming mode?

Thank you for your help!

I thought those were diodes - sorry my mistake.

I didn't try running the car & loading the script - I assumed that would be a bad idea. I've only connected it with the key off.

I did rework the wiring on the boards to simplify & used terminals slightly wider than the pre-made cables I had used
I will test this one. If it still doesn't communicate, I'll try switching out the CAN boards

Post by **vtl** » 18 Mar 2026, 05:22

lookforjoe wrote: 17 Mar 2026, 20:01 Thank you for your help!

I thought those were diodes - sorry my mistake.

I didn't try running the car & loading the script - I assumed that would be a bad idea. I've only connected it with the key off.

I did rework the wiring on the boards to simplify & used terminals slightly wider than the pre-made cables I had used
I will test this one. If it still doesn't communicate, I'll try switching out the CAN boards

Part with 103 on it is a resistor. 103 = 10 * 10^3 = 10000 Ohm. The other one is 121 = 12 * 10^1 = 120 Ohm.

When the cracker puts car into programming mode, it clicks with relays and goes blank. No lights, no dashboard, no nothing. It feels like a battery was disconnected or "this sh*t from the internet broke my car!". Then you get a cracking progress displayed in your terminal.

Chinese counterfeit chips is unfortunately our reality. Some chips are dead on arrival, some can even communicate, but don't have linear latency, so timing attack fails.

lookforjoe · Post by **lookforjoe** » 18 Mar 2026, 19:04

vtl wrote: 18 Mar 2026, 05:22

Part with 103 on it is a resistor. 103 = 10 * 10^3 = 10000 Ohm. The other one is 121 = 12 * 10^1 = 120 Ohm.

When the cracker puts car into programming mode, it clicks with relays and goes blank. No lights, no dashboard, no nothing. It feels like a battery was disconnected or "this sh*t from the internet broke my car!". Then you get a cracking progress displayed in your terminal.

Chinese counterfeit chips is unfortunately our reality. Some chips are dead on arrival, some can even communicate, but don't have linear latency, so timing attack fails.
[/quote]

Thank you so much for noting that! I'll go through the other boards & see if I have any with 103 on the resistor. Otherwise, I'll go through my stash of surface mount resistors - it's been almost 20 years since I worked with them - it will be a challenge to see if my eyesight is up to it