Having some problems with error codes on my 2004 XC70.

The local Volvo dealer closed several years ago, but there was a Volvo mechanic at another dealer, who, recently left and with him went the diagnostic software.

There is no place nearby that can diagnose a Volvo. The closest dealers are a 5-hour drive in one direction and at least 7 in the other. I don't have anyone to help me with this and I am quite sick, need my car for Dr. apts, and am not able to drive 5-7 hours to a dealer.

I figured out how to read the codes in the various modules, using the press READ/double-click the rear fog lamp. My codes are:

BCM Checking
SRS Ready
TCM Checking
ECM DTC Set
DEM Ready
AUM Ready
CEM DTC Set
DIM Ready
DDM DTC Set
CCM Checking
PDM DTC Set
PSM DTC Set
REM Checking
SWM Ready
UEM DTC Set

Question: The ones that stay in 'Checking,' I'm guessing that info is not available thru this procedure. Anyone know more about this?

Question: Do any of these modules report a problem with the locking gas cap/cover? Seems someone tried to break into it. I did not hear any audible alarm but when I started the car, the Alarm System Service Required message was on and stays on. The gas cap cover is intermittently broken (opens w/o pressing the release). Can't be more specific as it seems random, sometimes stays locked.

Question: Is there anyway to clear the Alarm System Service Required message? I tried clicking the key FOB on/off 3, 4, or 5 times with no result.

I took my car to the shop that used to have the Volvo mechanic. They did not tell me the mechanic and the software were gone. They charged me to replace the gas gap lock part, but did not check their work and the problem is unchanged. I did ask them to first check the errors but didn't know they were unable to do so until after. I wonder if the original part was even broken, I took it home and it seems OK (mechanically at least).

This could be unrelated, but the Check Engine light came on as I drove home from the repair work. The service advisor attached a handheld tester and got two error codes, P0299 and P0456, relating to 'turbo boost' and 'evaporative emission leak' (do not know what they are or if there are symptoms to look/listen for). He cleared them so I will drive and see if the errors return. The module ECM DTC Set changed to ECM Checking, and I guess will go back to error state if the Check Engine lights returns.

Questions: Would one or more of the computer modules alarm if the gas cap/cover is compromised? REM or ECM modules? If replacing that part had fixed the problem, would the related error have cleared on it's own? For an XC70, can a compromised alarm system not recognize the sensor/mechanism that detects/locks the gas cap? I do understand that some problems must be fixed before various alarms can be cleared.

Slight rant: I don't understand why Volvo will not document or even discuss the diagnostic codes (DTCS). They say it was because they were once sued. If you think about it logically, they could equally be sued for causing someone to drive a car with undocumented errors. I used to do technical work, not on cars, but compared to the type of stuff I used to do, I think it's a no-brainer to properly document this stuff. It would be a fair mount of work, but doable. Vatis (sp?) or similar systems are complex software, but I just don't see how Volvo can really think customers are too stupid to provide any level of technical assistance with the safe functioning of their autos. Maybe it's a $$ decision and not really a legal one.

Thank-you, any help is much appreciated.