Up until about a year ago, my local Advance Auto would run free diagnostics (i.e. hook up the car to get the 'code') but this is no longer available.

Does anybody know of any major chains that provided this service? And if so, do you know if they would be able to check out a '94 3800?

Really? My local Advance gives me the scanner and lets me go at it. Still, yours being an OBD-I engine, I can't say for sure.

being obd I I'm not sure but I think you can jump some pins and watch the Engine light blink. If not I know if you a rewards member of pep boys they will do engines lights for free. Rewards memberships are free also.

It depends on what he has. Even though it'* a 94, some of them do have the OBDII connector. Though his system is OBD1.5. If it'* the older 1.0 system, grab a paperclip and watch the flashing light.

Yes, Autozone does, otherwise ground terminal a and b on aldl connector with a paperclip. That would be the the two term'* next to each other on the far right, top row (there is a small tab on the top of the connector body to identify top) turn the ignition "ON' and count the service engine soon flashes.

I'm a complete newby when it comes to this type of thing. Could you explain a little clearer, what is an aldl connector? Where are these terminals, is this within the bank of fuses/relays under the cover at the top passenger side firewall?? This sounds like a 2-person gig? One under the hood- one turning the key & counting? Again, pardon my ignorance, and thank you.

Also, is there any way for me to determine whether I have OBD I or II connections?

does this help? https://www.gmforum.com/specifications-general-information-132/obd1-pinout-278836/

OK, I think I get it... 'jump' the A & B to each other, turn on the key and count the idiot light flashes. Where is this terminal block located?

should be under the drivers dash closer to the drivers door

OK, Thanks. So does the 12pin vs. 16 pin block determine whether the car is OBD I or OBD II?