Right, do NOT disconnect the battery. That would be bad, because it will erase the codes you have stored.
Basically you are going to short A & B together with the bent paper clip.
Then, turn the key on, but don't start.
If you watch the check engine light, it will start flashing.
First it will do "1" flash, followed by "2" flashes, which is a "12" and says the diag. is working.
After flashing "12" 3 times or so, Start watching and counting.
The first digit will flash (count) then the 2nd digit.
It will do this 3 times before going to the next code.
When it has displayed all the codes this way, it repeats, coming of with the "12" again.
You can shut it down and remove the clip now.
NOTE: It will display any codes stored since they were last cleared. So you may see some old ones too. Write them all down, etc. That way, you can later disconnect the battery to clear them and start over, with your test drives, or whatever, and see what codes are gone and which ones are showing up now.
Hope that makes sense. Force be with you.
1993 Red SSE - Bone-Stock except for High Perf. Power Antenna-Original Owner. Less than 130K - Love of my Wife
'05 Magnum R/T Hemi - Bunches of classic VW Beetles... and one "not quite stock."