How to downgrade SMC firmware I have a MBP 6.2. Some time ago (1,5 year I guess) I have installed latest Mountain Lion upgrade and my WiFi (airport) stopped working.
Tried many options, spent lot of time on different forums, did update to Mavericks and Yosemite but nothing helped. AirPort still refused to connect. 

I have small TLink wifi dongle and managed to make it working via Wireless Network Utility but the dongle has weak antena so MBP went to the cupboard for some time.

Recently I decided to install fresh Mountain Lion again hoping that maybe old software will help. I noticed that if I reset the SMC nadn NVRAM, AirPort connects and works for several minutes and then stops again.

Is it possible that the firware update has broken my Wifi ? I have the idea to downgrade to the previous firmware version hoping it will sove the issue. The version I currently have is EFI: MBP61.0057.B11 (2015-002) and SMC: 1.58f17 (SMC 1.7). 

And now the final question. Could anybody suggest a site where can I find list of SMC and EFI software versions proper for my MBP6.2? I have found this: https://support.apple.com/pl-pl/HT201518 but it says only what is the latest version. I'm looking for the previous one.

Best Regards
Hightower
Download the 1.69f3 SMC 1.5 Update from (MacBook Pro SMC Firmware Update 1.5). This gives you the file "MacBookProSMCUpdate.dmg", mount that and look for the file "MBP15.pkg" and copy that to your HD.
Download unpkg from (http://www.timdoug.com/unpkg/) and install it.
Open unpkg and drop the file "MBP15.pkg" on it. This unpacks that file into a folder called MBP15. Open MBP15 ▸ System ▸ Library ▸ CoreServices ▸ Firmware Updates and locate the file "MBP15SMC15.smc". Copy this to a folder on your desktop called SMC or something like that.
Now download the 1.69f4 SMC 1.7 Update from (MacBook Pro SMC Firmware Update 1.7). This files is also called "MacBookProSMCUpdate.dmg" so mine was renamed "MacBookProSMCUpdate (1).dmg" this may vary on your system so make sure you know which file is which. Mount this file and look fot the file "MacBookProSMCUpdate.pkg" and copy that to your HD.
Open unpkg again and drop the file "MacBookProSMCUpdate.pkg" on it. This gives you a folder called MacBookProSMCUpdate. Open MacBookProSMCUpdate ▸ MBP91 ▸ System ▸ Library ▸ CoreServices ▸ Firmware Updates and locate the file "SmcFlasher.efi" and "VerifyRequirements". Copy those to the SMC folder you created earlier. That folder should now contain 3 files "MBP15SMC15.smc, SmcFlasher.efi and VerifyRequirements". I´m not sure if that last file is needed but this worked for me. I also renamed the file "MBP15SMC15.smc" to "2011MBP15.smc" because that is the name of the 1.7 SMC that is used with that version of SmcFlasher.efi, again i´m not sure if this is needed.
We need a way to boot into an EFI shell. Download the disk image for rEFIt from (http://refit.sourceforge.net/). Mount that and copy the folder "efi" to the same place as your "SMC" folder, for me this was my desktop.
Use a USB drive, i used a simple 2GB stick, format that as HFS+ journaled extended, GUID partition table. Copy the two folders "SMC" and "efi" onto that drive. Start Terminal and run the script "enable.sh" that is located in "efi/refit" on your USB drive. Once again i´m not sure if that script is needed but this is how i did it =)
Boot your MacBook Pro and hold down "Alt", choose to boot from your USB drive. This brings up the rEFIt user interface, choose the icon that looks like the Terminal. This boots up your EFI shell. It will show you a list of your available drives. My thumb drive was fs2 so i just typed fs2: to mount that. If you mount the wrong one you can just type that command again, for example fs3: and so on. When you find the right one you can type "ls" and it should show you that you have the folders "efi" and "SMC". Type "cd SMC" to go into that folder. Type "ls" again and make sure your 3 files are there.
Now the fun part =) MAKE SURE YOU ARE CONNECTED TO A POWER SUPPLY BEFORE PROCEEDING!
Type "SmcFlasher.efi -reset 1" and then type "SmcFlasher.efi -force -LoadApp 2011MBP15.smc", your fans should now go to max and it will start flashing you SMC. Reboot when finished by typing "reset".
Enjoy 1.69f3, this made my fan controller work again, the fans now kick in as they are supposed to.