How to bring up ECM trouble codes

[doobiess]

I heard stick a paper clip in the 2 top right slots ... but on my 94 grand 3100 V6 auto there is only a connector inside on the far right and nothing in the one next to it... does this trick on this ECM or do i need a scanner?

[rixGAphx]

Neither.

The first models of On Board Diagnostics (OBD) were from about '94 to'95. They were know as OBDI systems.
OBDII was mandated for ALL cars sold in America from '96 onward.

OBDI's had a connector, and internal codes, that were specific to each manufacturer.
They could also be 'read' by some finaggling, such as the paper clip jumper for some manufacturers (for Chryslers, turn the key 'off'-'on'-'off'-on') then count two-digit sequences of flashes from the SES light.
You need the cipher of two-digit codes for your manufacturer (and model).

OBDII's generally canNOT be read on-board.
But, they have a universal connector (identical for all makes), and there are about 200 'standard' codes + however many 'auxilliary' codes each manufacturer needs.
Some scanners have the code definitions inside (electronically), others need a cipher book.

Your vehicle, IIRC, has GM's infamous OBDI-1/2; not quite OBDII, but a lot more complex than the paperclip read-on-board OBDI

My 'puter's about to crash, gotta go, I''ll be back.

-Rick

Edit - Back Again:
Remove key from ignition. NEVER play with the connector socket when the key is 'on'.
Your connector, if OBDI, is a 12-pin connector; 2 rows of 6 sockets each.
Upper right is Pin 'A'.
Next to it is Pin 'B'.
Insert one end of jumper wire into Pin 'B', and ground the other end. Easiest point of ground is Pin 'A'.
Then turn key to 'on' (NOT 'start').
The SES light will flash once-pause-twice (this means '12'); LOOONNNNGGG pause, then 12 again, LLLOOONNNGGG pause and 12 again. This was the 'handshake' signal, the ECM telling you it's ready to communicate.
Then it will pulse out whatever 2-digit codes it has stored, same as it did the 'handshake 12'.
But each code will only be flashed once, and in numerically ascending order.
NOT the order of priority.

The codes are in a Haynes/Chilton's manual, maybe even posted on this board.

Even tho the 'B' pin looks empty, try it anyway if you have a 12-pin connector.

I don't know what to do if you have another connector (can't be the 16-pin OBDII, your car was built before the configuration of OBDII was decided).

Good luck.