These are instructions on how to jailbreak your iPhone 3GS or iPhone 4 on iOS 5.0.1 without updating the baseband using RedSn0w for Windows. You may want to do this to preserve an unlock from a lower baseband version.
Please note this jailbreak is tethered for every device but the old bootrom iPhone 3GS which means you will need to connect your device to the computer each time you reboot. Also, it may be prudent to save your SHSH Blobs.
If you want to jailbreak a lower firmware version you can find the appropriate tutorial here.
Create a folder on your desktop called Pwnage
Extract the RedSn0w zip file by double clicking it.
Launch the redsn0w application from the redsn0w folder we just extracted.
Click to select Extras from the main menu.
Click to select Custom IPSW from the Extras menu.
Navigate to the Pwnage folder on your desktop and select the IPSW we downloaded then clickOpen.
If you are using the iPhone 3GS you may be asked to identify whether you are on a newer or older model.
RedSn0w will now begin building a custom IPSW for you.
You’ll be notified once RedSn0w has completed building your IPSW. Click the OK button.
Click the Pwned DFU button from the Extras menu.
Plug your iPhone into the computer and make sure its OFF then click the Next button
RedSn0w will now guide you through the steps to get into DFU mode.
Hold down both the Home button and the Power button for 10 seconds.
Release the Power button and continue holding the Home button until RedSn0w detects the device.
RedSn0w will run the LimeRa1n exploit.
You’ll then be notified that your iPhone is in Pwned DFU mode.
Launch iTunes by clicking its icon in your dock.
Select your device from the list on the left then under the Summary tab hold down the Shift key and click the Restore button.
You will then be asked to select your IPSW for restore. Navigate to the Pwnage folder on your desktop and select the IPSW that begins with NO_BB then click the Open button.
iTunes will now restore and jailbreak your device using the Custom IPSW.
JAILBREAK AND INSTALL CYDIA
Follow these instructions to jailbreak your device on the new iOS 5.0.1 firmware.
– iPhone 4
– iPhone 3GS
Once you have jailbroken you will need to rerun redsn0w to boot tethered.
From the main RedSn0w menu click the Extras button.
Select Just boot from the Extras menu to just boot tethered.
If you have a supported baseband you can now install UltraSn0w to unlock your device. Instructions are here.
*As usual a big thanks to the iPhone Dev-Team and Geohot for their hard work and contribution to the iPhone community.