Hi there Werdna, and sorry for the late reply..

Firstly, what were the error codes that were reported by the ELM327 ?
The reason I ask is that usually intermittently detected problems (Such as say an engine misfire, or a sensor reporting values out of range for a short period of time), will log a fault code, that can be cleared.
For permanent errors (Such as a sensor or module being unplugged, missing, or constantly reporting wrong values),
then the Diagnostic Trouble code will be permanently logged, until the problem is solved.
You can get some information on what the DTCs mean, by visting
search_dtc.phpThese pages have manufacturer and model specific Diagnostic Codes for the common Australian Holden and Ford Models,
which will give you much more information than the generic OBDII codes the ELM327 software will spit out...
Once you are armed with this information, its then just a matter of trying to sort out what sensor, module, or electricla connector is causing you problems...
In regards to programming modules,
Unfortunately, the common, fleabay variety off the shelf ELM327 cannot access either the G.M. single wire can, or high speed can directly,
as they do not have the necessary interface chips to connect to these lines directly.
Without these interface chips, you are severely limited in what G.M. allows you to do using the industry standard OBDII protocols.
(I.E. not very much unfortunately, just log basic engine data, view DTCs and Clear temporary DTCs)...
I hope this helps.
If you need any further information, post up the DTC codes you have, and I can have a look around and try and find out more information for you.
Cheers
Matti