94 lumina 3.4L "Engine needs Servicing" Light OBD-I

"Service Engine Soon" Light

What can this be?

I can't read codes, because the 94 Lumina is the one GM car that even their own code reader doesn't read.

I think it is supposed to blink when you short the reader-plug out, but I've never been able to make it do so.

I know it can't be the Catalytic Converter, because this OBD-I machine only has one oxygen sensor on it, BEFORE the CC.

Could the Oxygen Sensor itself be the culprit?

The OBD-I system is not supposed to even give errors unless a part or sensor actually fails completely.

Does anyone have a partial list of what turns on this light on a 94 (OBD-I) vehicle?

or any experiences with the "Service Engine Soon" Light?

This is the transition year for obd1 to 11, any code reader made to communicate with this 93-95 car will work,. see this link for codes. http://www.troublecodes.net/GM/93-95_34X.shtml

This is the transition year for obd1 to 11, any code reader made to communicate with this 93-95 car will work,. see this link for codes. http://www.troublecodes.net/GM/93-95_34X.shtml

Thank you for the listing.

I think "made to work with this car" is the 'key phrase' here.

The (under $100) code reader from GM and sold by Canadian Tire does every OTHER car but mine (including non-94 Luminas). You have to read the fine print. They won't plug into the different pin-out on the reader-plug.

Apparently theres a $300 third-party code reader out there, but its absurd to buy it just to read the codes.

I tried rewiring the plug to make the GM reader work, but it did nothing, and I had to return the unit, and get my $70 back.

I'm hoping for some insight from others on part II of my question:

Does anyone have a partial list of what turns on this light on a 94 (OBD-I) vehicle?

...or any experiences with the "Service Engine Soon" Light?


...by the way, what is a "TPS" voltage on this list?

and "EST" signal...?

Update:

I just had to send you guys this:


A guy I know fixed his SES light by putting black electrical tape over it.


It made me laugh, partly because I'm almost ready to try it.

But I have an E-test coming up next year, so I will probably have to solve this...

The thread where I got this was talking about software for diagnosis on your home computer, but even guys with whole fleets of OBD1 and OBD2 can't seem to locate OBD1 software/diag tools.

http://forums.hotrod.com/70/1296764/pit-stop/obd1-and-obd2-software/index.html

So I don't think I'm imagining the fact that GM has everyone crawling to dealerships just to get codes.

Update: I replaced the Diagnostic Link Connector (part from wrecker) which I had previously attempted to re-wire to work with the GM reader.

I tried the "Paper Clip" A-B short trick to make the SES (Service Engine Soon) Light blink the code for why the damn light is on while driving.

I get nothing. The SES light stays on, and no 'codes' are flashed at all.

This bugs me because it seems to mean that the "AB" short thing only works with some ECM/PCMs (once again probably every one but mine...?).

It might have something to do with the fact that I have a 1995 Monte Carlo PCM in my car, even though its really a 94 Lumina, but I doubt that. As others have noted, the PCM unit is supposed to be identical, and (other than the SES light being on) it works fine.

So I have no way of getting the code(s) out of this stupid thing once again.


I have one additional piece of information:

The SES light goes on (after car has been sitting for a while) after less than 10 seconds of the engine running (and stays on). I am hoping this is meaningful to someone out there as to what code it could probably be that is going off.

Wow this is annoying...

Update:

Either this is new, or I just noticed, that the SES light comes on for a few seconds, then shuts off for a few seconds, then comes on again for a few seconds when driving around the neighbourhood.

Is that normal or a special phenomenon?

There's a few dozen conditions that will light the light, trying to guess is useless.

No performance issues that might throw a flag at least?

Update:

Now the light comes on briefly when starting up, but then shuts off.

Could the computer have relearned the fuel mix or something?

My car is OBD-I...

here is a look at the OBD-I readout plug under the dashboard on the rightside of the steering wheel:


http://www.qzoka.com/images/wsfojtf66yck9pz04uph.jpg


I actually replaced this, after trying to move one of the pins over. The socket actually only has pins 1,2,3 connected on the right.

The apparent pin on the lower left is just bad lighting. no metal or wire there.

Here is the supposed pinout of this plug:


http://www.qzoka.com/images/22j6a1q81tu6trd1v5l.gif

The 160 Baud connection is optional (and not found on the Lumina). I tried shorting A & B and did not get any flashing readouts.

Only A, B, and M are connected on this car.