OBD I System with OBD II Connector ???

A friend of mine has a 1994 LeSabre with an OBD II connector (16 pin) although he says it is an OBD I system (which should be a 12 pin).

My manuals tell me that he should have an OBD II system for that year.

He said he was told by mechanics and auto-part stores that read the PCM codes that his system is "unreadable" with a scan tool because he does indeed have an OBD I system. I tried reading his OBD "X" system with my scanner last night and although it connects to the 16 pin (OBD II ??) connector, it will not read.

Someone else mentioned a special adapter, a concept which I am not really understanding.

If it's an OBD I, he should be able to tie the "read" pin to ground and read the codes from the dashboard SES lamp. However we have no info on this and especially no pin designation.

Could it be that someone installed a different PCM at some point in this vehicle or a different connector for whatever reason?

Any help would most certainly be appreciated.

It has OBD 1.5 so an OBD II scan tool would not be able to communicate with the PCM. here's a link on this topic
http://www.automotiveforums.com/vbulletin/showthread.php?t=911305