DTC code questions

I"ve got a neat little Equus 3110 code reader, and have been using it a lot to help me troubleshoot my 2000 Intrigue. Can anyone confirm the following behaviour as normal for code readers:
1. With engine off, they don't see any codes if the SES light is not on. I believe (correct me if I am wrong) that the SES light only goes on for an emissions-related fault. That covers a lot of territory, but is still restricted to only those DTCs related to emissions. My car doesn't have any emissions problems, so my SES light is never lit, and my reader never sees any problems (engine off). The SVS light is not lit either (except all go on at "bulb check" vehicle start, of course).
2. I leave it attached while I drive. This particular code reader "auto-relinks" every 40 seconds. Don't know why it has to do that (can someone tell me? -- Equus couldn't--), but that is how it is designed. Often it fails to "auto-relink" (is that normal?), but pressing the relink button once or twice then does the trick. While driving, the scanner will show occaisional DTCs, which are only shown during that 40-second link cycle. I write them down to research later. I have a set of the official factory manuals for the car. There is a long list of DTC codes in the index, but I was disappointed to find that many DTC codes that I've documented while driving are not listed. I can get a definition from my code reader's built-in library or from the many online DTC code lists, but I'm puzzled why GM wouldn't provide this info, as well as circuit details for setting/resetting these DTC codes, like they do for the codes they do include in the manuals. Can anyone shed any light on why the manuals aren't complete? Where would a dealer mechanic go for info on these DTCs, if not the official manuals?
3. Even though this code reader can't see them, is the PCM storing the codes I see while driving so that a dealer's Tech2 gear would see them? I am aware that the rules for saving DTCs are complex and vary, depending on many things (DTC type, etc), but in principle, is it at least possible that there are codes in the PCM that the Equus is not able or programmed to read?
To add to the fun, I get codes like P0047, which is defined as "turbo/supercharger boost control ckt low". News to me that I've got a supercharger in here somewhere. Codes occaisionally have question marks, or they may have alpha characters in the last four positions. I am quite sure the last four positions should be numeric only.
I have contacted Equus via email and phone, with some of these questions, but have not gleaned much info. Hope the forum can help again. Thanks for any (clear and accurate) information.

1. With the engine off there is no 12 volt power to read anything. There are more than just emmission codes.
2. Don't leave the code reader on while you drive unless you realy have a problem. If the code doesn't set there is no code.
3. Yes there are codes that you can not read. And somethime codes are set that do not exist. Do not worry about them.

Taillight -
Guess I wasn't clear enough; sorry.
1. I meant the "key on, engine off" condition, the way AutoZone or Advance would check it. There is 12VDC, and the code reader works, just always indicates "No codes stored".
2. I really have a problem, so I run with the reader connected. It is the only way to "catch" the codes that only appear during drive time.
3. I am more concerned about the valid codes that appear, not (apparently) invalid codes, or codes with invalid characters in them.
Hope some more of you will provide some input. Thanks again.

Problems have to be seen with some degree of regularity before it will illuminate the SES light. There are also different rankings of codes, A,B,C, I believe, and the lower the ranking the more times it can occur without the light illuminating.

Are you actually having a problem with the car?

http://service.gm.com/gmspo/mode6/pdf/2000/2000file9.pdf
http://service.gm.com/gmspo/mode6/pdf/2000/2000trans8.pdf

I think your p0018 Code is bogus also. We have the Equus 3100 and all the codes we have gotten are good/legit. Yours is the upgraded model to the 3100 and should be better.

Even with the p0018 code that is bogus I still think it's a CKP issue for you.
http://www.iequus.com/products.php?category_id=1_10_7

http://www.iequus.com/images/category_images/7/obd2.jpg

-There is always the Tech2 going to the dealer option also.

What is the problem you are trying to find ? Are you getting any codes at all ?

LittleHoov -
Yes, actually having a problem. Engine occaisionally stumbles or stops, at idle or on the road. Sometimes recovers, sometimes not. I was considering CKS/CPS as well as ignition switch. (Separate thread; this thread was supposed to be informational questions about code readers and DTC codes.)
Anyway, the problem got a little worse (occurred two days in a row, yesterday and day before) so I decided today to try cleaning the ignition switch contacts before anything else.
Your instructions on removing the ignition switch were very good. A most helpful post; thanks.
Car started and ran OK afterwards, but it is too early to tell. If this doesn't do it, I will proceed to replacing CKS (or maybe replace the ig. switch). We shall see.

Here is LittleHoov's very useful link on the ignition switch removal:
http://www.automotiveforums.com/vbulletin/showthread.php?t=736656&highlight=ignition+switch+removal

I have the 3110 wich also does the auto relink. I got it to diagnose my car when i got it....and it has helped alot. I like the feature of telling you the code definition on-screen as opposed to looking it up. The only code I pull now is "small evap leak" wich comes on every few weeks after i clear it. There are seemingly endless amounts of dtc's that trigger your engine light, not limited to emissions. If your car has a problem, it will store a code for you to read later. Therefore it is not nessecary to leave it plugged in as you drive. Sounds like a misfire condition thats either not lasting long enough or serious enough to trigger a fault code. Very strange to get a code related to a supercharger!

Harmonkardon,

You may have the same problem my father in law had on his 2000 Intrigue. I had to replace the gas tank filler tube vent pipe on it as it rotted out due to our fine Ontario road salt and notoriously bad undercoating spray companies. The SES light came on every time I cleared it. So, I put the car on jack stands and started looking at the EVAP system. Low and behold, there was a break in the line. If I recall correctly, there was some kind of quick disconnect under there somewhere between the tank and filler. I cut it out and replaced it with hose I think. His SES light has not been on since.