Need Quick Help, how to can I pull codes from '91 Jetta? (GAS)

[GmDieselTech]

I am not at my shop, on vacation, yup you guessed it helping a friend their car,
its running rich black smoke, GAS ENGINE
would like to check codes,
it there any way to check without scan tool or code reader? (like the paperclip method on the older GM cars?)
What is the common part failure for this condition?
O2 sensor???

Please reply ASAP
Thank You

[boschmann]

I see you're in California, so I assume this a CA car (it will say so on the hood emmissions sticker). If it is it will have a Digifant I system, most easily identified by not having a small ignition control unit mounted on top of the ECM (under the hood, back on driver's side under cowl). It should have a check engine light which will flash codes. The connectors to enable this are located in front of the shifter, under the shift boot (unscrew the shift knob & pull up the boot and trim). You can connect the two pins w/o the special tool as follows: turn the black connector so the two chamfered edges are at the top, connect one end of a jumper to the bottom pin (ground). Turn the light colored (could be blue or white, but not the brown) connector so the chamfered edges look like a D (on the right side), connect the other end of the jumper to the bottom pin (engine control). To get the codes follow this proceedure: Turn on ignition, connect the jumper for about three seconds then disconnect it. The check engine light should do one long flash then start a series of four digit codes, seperated by long pauses. It should repeat when all have been displayed. Code 4444 is end of codes/no codes. If you get a pile of codes you can reset them by doing the following: Connect jumper wire, turn on ignition, after three seconds disconnect the jumper & turn off the ignition. Post the codes here & ill give you their meanings. Just a note, if it's running rich you might want to check the coolant temp sensor. It's on the coolant flange where the upper radiator hose leaves the cylinder head. It is a two pin connector. It should read about 2000-3000 Ohms cold and steadily decrease to 250-350 Ohms @ operating temp. Aside from that the most common thing on those systems that results in rich/flooding is a fried ECM, they are notorious to fry if the various engine grounds get corroded or loose.

[GmDieselTech]

cool
I had to leave there by the time i read this, but will be back at it early next week.

I will check to see if it is a CA car, could have been brought in from other state.
Then I will check for the codes...

thank you!!!