2001 Saturn L300 I/p telltale & mil lights

Yes I believe it is. Emissions is CALIFORNIA. Does list it as CAN. Here is the vin if it helps
1g8jw54r21y577991

You saying "and the module that set the DTC begins communicating" in your responce has me wondering if you noted that in my orriginal post I stated there are No DTC's . I have an Actron cp9180 which includes controller area network. please read all my original post to avoid redundant info. Scan tool shows no codes & no pending codes, yet these lights persist ( SRS, ABS, & SERVICE w/wrench)
Here are some samples of yesterdays circut testing and checking

Everything has been re assembled

When implying a result of "no change after unplugging." Are you suggesting I unplug modules and power up the system & or plug & unplug with power hooked up? And which module is in question? The service light (BCM) will come on just because one of the other MIL lights is on. Whats also crazy is the scanner says all mils are off when they are not.

I do in fact have a lot more information, I just needed to get us on the same page & headed in the same direction. I appologize for the mix up about 'CAN'.
Now as for the history of the vehicle- No it most certainly has not been in a wreck. There has been 2 previous owners, ( mother -daughter) It has had a brand new transmission installed & from what I have found out, that seems to be the last major repair it recieved before being dormant for a while.(Carfax)
I understand the requirements for re-calibration of TCM after transaxle replacement and it all seems to have bben done.
Now this is where it gets good.I bought the vehicle with smoke pouring out of the exhaust, barely running, & code 300 (or maybe 303) #3 mis fire detected. In a nut shell, had somehow put too much oil in it and thought the motor was no good. A total of 8.5 qrts to be exact. After an oil change, tune up, and replacement of the rear bank coilpack (front had already been recently done) plus a complete tear down of the intake, plentom, air cleaner hosing, pcv sys, to remove engine oil, the engine has ran outstanding. No codes or SES light. This was well over 600 miles ago.
I am sure you will wonder how well of a job I did or didn't do. I will say this, I do it right or I won't do it at all. When it comes to Diag. I get obsessive.
The SRS module I have sent out to have the software re-installed & reset, with fingers crossed. Its only $49.
Its the BCM that has become the main focus, see if you can find out if it is normal to have mil's lit up without the presence of any DTC's. Even if I don't get to the bottom it, you will be compencated, I am going to go put money on my card now.

Yes, yes, & yes. No worries about how long it takes to reply, as long as you keep replying. My friends call me DR. Phil cause I got lots of patience. I am totaly on the same page & have already conducted the wiring harness tests for the BCM. I have aquired all the wiring diagrams for the car but I'm not sure if I have that particular one, I will check at the garage tonight cause the writing isn't readable & gets worse when magnified. In the event that I don't have that diagram, I will be going over the harness again using that one as the referance for distribution. I too, dreadfully suspect the BCM, but want to be absollute before replacing it. Aside from the lights, it seems to perform its functions without any isssue's. Replacing one just because it can't turn the telltales out, its a joke but not funny. Your conclusions so far tell me I have been headed in the right direction. I will add the findings & results of the wiring review tonight.

Wet, wet, wet. I found evidence that the BCM has gotten wet at some point in time.
I was unable to enlarge the diagram without distorting the text, When the image is shrunk the pixels for the writing get screwed up. See if you can send it a little larger because I do want it for referance to continue testing.
It dawned on me today that theoreticly I could check all the leads coming out of the BCM that are supposed have (& correct me if I am wrong) a.5 volt to find a possible confirmation of the problem. What do you think? I believe I have the nessecary diagram to get that done.
Even though the SRS brain is out of the vehicle the light still flashes 7 times. That doesn't make sense to me, does it to you? I thought the flashing was a form of communication from the SRS that it was functional. Now this is obviously from the BCM, does this constitue BCM failure?

OK will do.
Moisture is from windshield, am having it replaced.
Still waiting on SRS brain, will notify As soon as it arrives, will not be doing anything else until wiring checks are complete

SRS came back with "internal failure " written on it.
I am at a loss for what to take care of first. Gimmie your best suggestion, thanks phil

When it comes to calculating my costs, I should tell you I work for myself. I look for vehicles in this condition & purchase them, repair them & sell them. I only like doing things one way, the right way. My funds aren't unlimited so Of course I want to avoid replacing anything that doesn't need to be replaced.
But what ever it takes to get it done right is what I will do, and my labor is my most abundant asset.
Now, the more I think about the SRS module, the more I wonder how 'they' (it was myairbag. Com) where able to determine 'internal failure', especialy since the airbags have never been deployed & the vehicle never wrecked. Although I need to make sure the SRS system is fully functional before I sell the vehicle, my main concern for now is the mil lights, & main goal over all is for the vehicle to be without any mechanical needs period.
Lets focus on the BCM & ECM, I want to be certain that they need to be replaced, before replacing them (which will also mean reprogramming them) & that there is nothing existing that will cause the replacements to fail.
Even with the combination of information from Alldata, repairpath, & chilton, I am still unsure about which module is responsible for illuminating the mil lights or how to be certain if a specific module is bad.
I actually infact have not spent alot of money in parts. The ign coil pack is been the most so far.
I was left confused with your last set of instruct. About "we should check the connection
( wire) between the BCM and the PCM." According to the diagram I have for the PCM, there are 2 wires that are responsable for this. They are Tan & Tan w/white they are labled BCM CAN HI & BCM CAN LOW. Other than verifying that there is no loss in conection from one plug to the other (which I have & they are good) is there any way to check the signal going between them? IF ANYTHING most of all thats I need to know from you for now.
Also the diagram you sent covers everything for the auto-doorlock system which checks out just fine.

I do have a brand new developement with the vehicle. It died the other day right about the time it reached operating temp (185). For the first time ever I got some DTC's out of it when it happened. Of course if you let it cool, starts back up. Sounds like PCM has failed & as soon as it leaves limp mode, it dies. The codes stored were p0727 engine speed sensor signal, 1810 trans fluid pressure position switch, & p0443 evap purge silinoid control circut.
Where in the hell is the engine speed sensor on this, I found the cam & crank position sensors, but can't find in any componate location chart that tells where the speed sensor is.
I am shopping arround for a tech tool capable of handling the programming and calibration of the PCM, BCM & ECU type, any suggestions.
Take your time and read over this more than once because I know I get consfusing, & if you say it's time to, the BCM will be the next on the list to be replaced, or if you think we should check something else out first let me know.

P.S. Bought the car for 600 & have about another 200 invested so far, so if I can get this all worked out for under 800-1000 I'll be ok.

Well, first of all, the code P0727 is stored when there is 'no signal' detected, not low, the exact definition per Saturn is 'Engine speed no signal' However, anybody can look up what a code referances, often it is not the cause of the problem but the result of the problem. I have manufacture's code definitions, what I can't seem to find is step by step trouble shooting charts for this vehicle.
Peviously you had said,
"I checked it out, it is not CAN system on yhis car, the can system are on vehicle made from 2003, this one is 2001."
Now how can "CAN bus circuit is open" be a possible cause, if this is not a CAN system. Naturally, if there has been a "no signal" circut problem detected then it is safe to say there is an open circut somewhere but where?
I am also confused about the reply you made about the SRS brain box.
"if there is internal faillure as you said have it replace."
I want to make sure that you understand, I was not the one who determined internal failure. At some point I will confirm it by eliminating all other possibilities for the SRS light being on, I dont go ahead with repairs until there is no "if's".
As for what I think, I need to know where the sensor for engine speed is & how to test it's signal, check the circut so I can confirm wether or not it's at fault for code P0727 or if it's the module itself that has the circut failure resulting in signal loss.
Do you have access to componate location for the Engine speed sensor?