Help with a 2004 Volvo XC90 CEM

**droidwayne65** · 26th January, 2022, 12:24 AM

I have this CEM, without a working key, where about the last half of the Flash was erased. I was able to get the original's VIN, key and sync info, with which I modded the donor CEM file then added a key. I'm not very familiar with Volvo CEM, so could someone who is check this file and tell me what else needs to be done? Enclosed are the original and modded files. Thanks.

**droidwayne65** · 26th January, 2022, 04:07 PM

Well, I tried the file as-is and the car would not turn on, except for the "check engine" light on the dash. Tried again after altering just the VIN, with the same result. This leads me to suspect it's a checksum error but, for the life of me, I can't find any data that looks like a checksum after each block. So does anyone know where to look for checksums or of software that can do the calculation?

**MartiLer** · 26th January, 2022, 06:43 PM

everything is done by hand. first you need to show the original damaged 28f400 dump and the ECM dump. what you posted in the first post is not useful to you. And don't forget the config. Other people's dumps are bad helpers in Volvo.

**droidwayne65** · 26th January, 2022, 08:01 PM

Originally Posted by MartiLer

everything is done by hand. first you need to show the original damaged 28f400 dump and the ECM dump. what you posted in the first post is not useful to you. And don't forget the config. Other people's dumps are bad helpers in Volvo.

These are the original files plus the one I've been trying to mod.

**MartiLer** · 26th January, 2022, 08:41 PM

try replacing flash. your intel is dead. and you need to work with this CEM using BDM contacts.

**droidwayne65** · 26th January, 2022, 09:06 PM

Originally Posted by MartiLer

try replacing flash. your intel is dead. and you need to work with this CEM using BDM contacts.

I realized that and swapped it out. I am now the third person to work with this car but I just managed to track down the original locksmith who worked on it. He sent me his first read but he says the car went dead after writing it. I'm not sure whether the file is bad or maybe the flash went bad. Could you please take a look at it?

**MartiLer** · 26th January, 2022, 09:24 PM

this dump also has errors.

**droidwayne65** · 26th January, 2022, 09:49 PM

Originally Posted by MartiLer

this dump also has errors.

Ahhh, K. Are you able to repair them?

**droidwayne65** · 27th January, 2022, 12:23 AM

Originally Posted by MartiLer

try replacing flash. your intel is dead. and you need to work with this CEM using BDM contacts.

With which programmer? I've identified the BDM contacts but I've never tried to use them. I usually just remove and reinstall the flash.

**Weasel3** · 27th January, 2022, 09:53 AM

Originally Posted by droidwayne65

With which programmer? I've identified the BDM contacts but I've never tried to use them. I usually just remove and reinstall the flash.

28f400

J-tag Smok

**janusz21** · 27th January, 2022, 10:20 AM

28F400 wery sensitiwe hot air see my post after desoldering flash is not working

https://www.digital-kaos.co.uk/forums/showthread.php/652451-CEM-VOLVO-S60?highlight=28f400

**janusz21** · 27th January, 2022, 11:00 AM

and se this test

https://www.youtube.com/watch?v=szoaJSq3guI

**MartiLer** · 28th January, 2022, 09:45 AM

I use a homemade programmer. today it is the cheapest and highest quality programmer in the world. its cost is only 20 euro. And anyone can easily assemble it.

**droidwayne65** · 28th January, 2022, 03:14 PM

Thanks fellas, and a special one to @MartiLer. This has been an education. I've been messing with these units for years and I guess it's just been my good fortune to have never run into a problem quite like this. I think I've used the flash removal method for the last time.