Vida CEM swapping

Post by **vtl** » 21 Jan 2026, 11:05

Do not power CEM before the cracker. Start the cracker, wait for "Putting all ECUs into programming mode", only then apply power to CEM. You have 5 seconds to do so.

vfred748 · Post by **vfred748** » 21 Jan 2026, 11:56

I do not have the "Putting all ECUs into programming mode" message on display or monitor in arduino.

Here's the arduino monitor.

Thanks

Post by **vtl** » 21 Jan 2026, 12:00

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

it says:

#define CEM_PN_AUTODETECT /* comment out for P2 CEM-L on the bench w/o DIM */

vfred748 · Post by **vfred748** » 21 Jan 2026, 13:21

Already done

no change

I think there is something wrong with the pin on CEM.

Post by **vtl** » 21 Jan 2026, 13:22

Can it read part number now? Power up Teensy, wait for message, power up CEM within 5 seconds.

Treur · Post by **Treur** » 21 Jan 2026, 14:11

From TechNest

Post by **vtl** » 21 Jan 2026, 14:34

vtl wrote: 21 Jan 2026, 13:22 Can it read part number now? Power up Teensy, wait for message, power up CEM within 5 seconds.

No way it can't work on the bench. I spent long months with CEM-L on the bench, hundreds of runs.

vfred748 · Post by **vfred748** » 22 Jan 2026, 09:26

vtl wrote: 21 Jan 2026, 14:34
vtl wrote: 21 Jan 2026, 13:22 Can it read part number now? Power up Teensy, wait for message, power up CEM within 5 seconds.
No way it can't work on the bench. I spent long months with CEM-L on the bench, hundreds of runs.

So i will make it on car, thanks for the advice.

Post by **vtl** » 22 Jan 2026, 09:49

vfred748 wrote: 22 Jan 2026, 09:26
vtl wrote: 21 Jan 2026, 14:34
vtl wrote: 21 Jan 2026, 13:22 Can it read part number now? Power up Teensy, wait for message, power up CEM within 5 seconds.
No way it can't work on the bench. I spent long months with CEM-L on the bench, hundreds of runs.
So i will make it on car, thanks for the advice.

I said it works on the bench. I ran it once, maybe twice on a real car

Remove autodetect line, compile/upload, wait for the message, power up the CEM quickly.

swital · Post by **swital** » 22 Jan 2026, 12:57

I just managed to read the PIN on my C30. Can I check the previously read code after unplugging the Teensy and plugging it back in? Is it saved somewhere?