The ignition barrel is supposed to pop up slightly when you remove the key from the ignition switch. It is common this mechanism gets dirty after a while so it doesn't pop up after you remove the key and the car thinks it is still in the OFF position. This leaves your accessories on and may drain the battery. It also sounds the reminder gong when you open the door. Pretty annoying.
Fortunately, this is easy to fix. There are instructions in the WIS and I have read some written instructions online but couldn't find any detailed pictures. I had a bit of a hard figuring out the catch in the cylinder works so perhaps this tutorial will be helpful for others. This is for a 2004 Saab 9-5 and I assume it is the same for all first generation Saab 9-5 model years.
Remove the transponder by turning it clockwise and lift up.
The plastic cover on mine is pretty loose so I took that off first so I could see what is underneath. Same procedure in turning it clockwise. You may have to wiggle it a little before it comes off.
I also removed the other plastic ring from the barrel but that's probably not necessary. The transponder doesn't need to be unplugged, just moved it aside.
When you try to start the car now, it shows a message on the SID saying there is something seriously wrong with the theft protection system. Proof that the transponder actually works!
Turn the key to the OFF position
There is a small square hole at the base of the housing (yellow arrow).
Use an Allen key (hex wrench/key) or other curved metal rod/tool to push in the release on the ignition cylinder. You have to push a bit to the side in the direction of the red arrow. The top of the red arrow ponts to the release on the cylinder. If you push perpendicular on the release, nothing will happen.
Push in the release, pull the key and cylinder up. This may take a few or many tries, especially when you're not sure where the release is and where you have to push.
The above picture show the ignition cylinder already pulled up so you can see the release and its position. This detail shows the scratches on the release where I was pushing in the wrong place/direction.
This picture shows the Allen key with the ignition cylinder removed.
After the cylinder is removed, you can un-clip the plastic part on the bottom and remove the spring and washer. Nothing else comes apart.
I am sure there are several ways to clean the cylinder. I used a small container with gasoline/petrol and let it soak for a few minutes. After letting it dry, I applied some lubricant on the moving parts. I wasn't exactly sure what to use and several sources said it is not a good idea to use WD40 or other stuff that attracts dirt. I had an old can of motorcycle chain Teflon lube and that seems to work great. If anyone has any other suggestions for cleaning and lubrication products to use, please respond to this thread.
Assembly is the reverse of the removal instructions. It pops up every time now and feels smoother when it is turned. Mission completed. Total time was about an hour but I can probably take apart, clean and put back together within 10 minutes after I know how that pesky release works.