If after installing your new miniPCI card into your ThinkPad laptop you get an 1802 error at boot, here is the solution.
Disclaimer: This worked for me, but I am unable to make any guarantee that it will work for you. Furthermore, if you really care about IBM's warranty, you may want to pass this one and buy your miniPCI card from IBM directly.
After getting my ThinkPad R40 from eBay, I got a wireless miniPCI card from there as well. I bought an Intel card, to avoid any compatibility issues. Little did I know... All recent ThinkPads have an internal list of miniPCI cards they will accept. Note that this is not only based on the model number, but also some internal numbers which are different for different batches of the exact same card.
Here is a detailed explanation. The simplest solution is:
- download no-1802.com
- boot into DOS mode
- run no-1802.com
If nothing happens - you should be able to finally install your card.
If your laptop came without a floppy drive, you may need to create or find a boot CD. I found some free boot-CD-generating program and created a CD with an option to boot into Windows 98. If you have Easy CD Creator, Nero, or some such software, they all let you create boot CDs, but you may need to obtain an image of a bootable floppy disk first (which means you have to create the CD on another computer that does have a floppy.)
This Command-Tab post has links to CD ISO image and a floppy image you can use.