"I have the Actron Scanner CP9145 and the GM ALDL Cable CP9127 for reading codes on this 1994 Olds Cutlass Ciera S, which has the "transitional" OBD "1.5" PCM with a 12 pin connector which uses pins A,K,M. There is no pin B.

Do not short pins A,K,M - it will not read codes by shorting and shorting can ruin the PCM. Codes must be read only by using the proper Scan Tool and Cable.

If needed, anyone working on this car may use my Scanner. I will gladly set it up for you."

1994 Oldsmobile Cutlass Ciera S 3.1 V-6 Engine Code "M"
When we first bought our Oldsmobile, I didn't know anything about it except that it looks good, runs good, has low miles and I found the complete history of it on the Internet, plus the price was right. I didn't do a mechanical check up of the car. I knew I would buy it so long as the engine and transmission sounded good. My wife and I drove it and bought it.

As soon as I got the car home, I wanted to check the engine codes. I got my paper clip and looked for the ALDL socket. It has the 12 pin socket and I wanted to short the A & B positions to read the codes by the flashing light on the instrument panel. I expected the 1994 Olds to have a standard OBD-1 system.

To my surprise, there was no metal connector in the B position. Only three of the 12 slots had connectors in them. Those were A, K and M. Ah Ha! I thought I had found my first defect, that being a broken ALDL socket.

These are how the 12 slots are identified.
My Olds has no B connecter, only A, K and M.
Shorting those could ruin your computer. You must use a scanner to check and erase your codes. 

After discovering that my ALDL didn't have a "B" connector, I went to the Internet to find some information. I found a lot of information. Some good and some bad.
Here is some good info: On vehicles made during a "transitional" period from about late 1993 through 1994, and 1995 for some vehicles, manufacturers were switching their sensors and computers from the old OBD-1 to the new OBD-2. During that switching period, vehicles had a mixture of the two systems.

Many technicians began calling the "transitional" vehicles OBD-1.5. They are not completely OBD-1 and not completely OBD-2, so OBD-1.5 is a logical label for these systems.

The OBD-1.5 may have a 12 pin or a 16 pin ALDL. It might have an inside computer or an under hood computer. You will have sensors for monitoring more or less vehicle systems. (Perhaps manufacturers were using up parts on hand while adding new parts.) Those are items that you alone will have to determine by sight, testing, and a bit of study. Or you can take your vehicle to a shop and unless the mechanic is familiar with your particular vehicle, he will have to do a bit of study at your expense.

Since I wanted to do my own testing and clearing of codes as often as I wish, I wanted my own scanner. I bought the Actron Super Auto Scanner CP9145 with its companion GM 12 position connector cable. The pair cost about $135.00 through Amazon.com. It is worth the money. It tells me what I want to know.

Another thing to know is that the special OBD cable that goes with the CP9145 for the "transitional" vehicles is a different cable for different makes of vehicles, such as the GM cable will not fit a Ford vehicle. ALL different MAKES of vehicles need a special cable for that make of vehicle if you are testing the "transitional" system or earlier OBD 1.

If you have an OBD-1.5 "transitional" system, beware of cheap code readers. Do a little research before you spend $40.00 or $50.00 for a cheap code reader that will not work with your OBD-1.5. Those readers are generally made to fit and read the OBD-2 systems only.

I suggest that you go to   http://www.actron.com/product_detail.php?pid=16150    and check the CP9145 scanner. It comes with the OBD 2, 16 pin connector but for the 12 pin ALDL connector, you will need the extra cable to fit your make of vehicle. Don't let the retail price of the CP9145 and special cable shock you -- they are available through other sellers such as Amazon.com for much less.

Also, if yours is a "transitional" vehicle, you cannot trust the expertise of your local parts store employees or shadetree mechanics to know everything about all vehicles.

When I take our 1994 Olds to a shop for service, I take a printed copy of the following NOTICE and tape it to the steering wheel:

I went to a local Auto Parts Store and asked a friend if he knew how to read the codes on a 1994 Olds. He said, "Yes, just short out two pins in the connector socket and the code will flash on your instrument panel."  

Then I handed him 6 pages of information that I put together explaining the OBD-1.5 "transitional" vehicles and the danger of shorting the pins when no "B" pin is in the socket. That was at a nationwide, well known Auto Parts Store and no one in there knew the danger of shorting pins when there is no "B" pin in the socket. So don't expect everyone who sells parts or service to know the difference. After all, in 2010, this is a 16 year old vehicle.

A mechanic who knows the difference will usually smile upon reading my notice.

Below, I copied and pasted two responses concerning the OBD-1.5 from  Internet forums. They are typical of the confusion that exists with these "transitional" vehicles.   

The following applies to my vehicle. Your vehicle may be entirely different. I am not a mechanic and not even a good do-it-yourselfer. This page is to remind any reader to do your homework before parting with your cash.

"Don't try jumping anything. You will do damage.
You are caught in the transition vehicle. That vehicle is half OBD1 and half OBD2. You cannot get codes manually and you cannot use a simple code reader.
The only way to get codes out of this year vehicle is with a class 2 scan tool and not just a code reader.
The ECM is OBD1 but the communication system is OBD 2, known as OBD 1.5"

"Yes, I am sure it is A, K, & M . I made this determination using my Haynes Repair Manual for this vehicle. I have come to understand that this vehicle was caught in a transition when GM was switching from OBD1 to OBD2. Certain 94 & 95 models, because of changes in the ECM, are different from all those before or after them. Jumpering terminals A & B will not work as on other models because there is no connection to pin B. I would like to buy a code reader that would work for this car. Do you know of one? I would like to be sure before I buy it."

If Pin "B" is not present in the 12-pin connector: Use the SUPER AutoScanner CP9145 with a GM ALDL Cable CP9127 or use the SUPER AutoScanner Kit CP9150.

OBD 1.5
Here's a sample of the information available on the Actron Web site. 
Good Luck with your "transitional" OBD!