[mackay85]

Originally Posted by rob00158

The process is fairly involved and does have some costs associated with it. Usual disclaimer - you do this at your own risk. I'm happy to share my experience and knowledge but I accept no liability.

I'm assuming you wish to avoid the dealer and their costs completely and your don't have access to a genuine Volvo Dice and Vida application with subscription?

If you want to have a go at doing this yourself, you will first need to "crack" the programming code for your CEM. This will allow a program called VDASH to make configuration changes to the CCM.
This code can only be cracked with a Modunlock tool (which you can buy or rent).
Alternatively, you can make your own tool (more on this later)
Or, if you live near Bedford I can also do it for you for a beer (it'll take about half an hour)

Once you have your CEM PIN, you can use a program called VDASH to reprogram the CEM to "remove" the 4C. The cost for that is circa 130 Euro. It is purchased through the VDASH program. VDASH can be found online and is free to download but the pro version has a cost associated to it as does any configuration changes to the car.

You will also need either a genuine Volvo Dice, a good Chinese clone DICE or a VCX Nano USB tool to allow VDASH to communicate with the car.

If you aren't local to me and you want to look at making your own decoding tool, you can find all the information on github. Just google search "Volvo CEM pin cracker via OBD"
You will find two designs of decoding tool on github, I have made them both and both work equally well. One design calls for Bosch VF160 transceivers which don't seem to be readily available. I managed to get some from the US on eBay. The other uses SN65HVD230DR transceivers and requires two 10k ohm resistors as well.
You will also require a Teensy 4.0 development board (£20 to £30) and is the brains of the tool. I'd suggest one with pins to save soldering.
You will need to download Arduino 1.8.19 version and Teensyduino to compile and load the code onto the Teensy board. The code is on github (volvo-cem-cracker.ino)
You will also need to make your own custom OBD2 cable to connect the tool to your car.

I guess in the first instance take a look through some of the above online and see what you're happy with doing, how far you want to go and what you're looking to spend. Initially it's a lot of effort to go through to turn off a warning light, but once it's done you can make further configuration changes if you wish with VDASH. VDASH is also a useful tool for reading and clearing trouble codes...

I can't private message anyone as I'm too new and haven't posted enough. I'll try and help with any queries.

Will this work if I simply want to turn the light off and have it stay off? I'm not planning on physically removing the 4C system. I have a 2005 XC70.