1988 Pontiac Boneville. ECM question for code 26

Car: Pontiac Bonneville 1988 3800 engine

For one, I don't have an OBD scanner, I'm using the paperclip approach to read the ECM trouble codes. Another factor is the fan does not turn on when I short A and B for diagnostic troubleshooting (I don't ever remember the fan coming on in diagnostics at any time for this car)
For now, I have to wait till Wednesday the 30th to do anything else on it since my wife uses it for work.

All it is giving me is a code 26, which is listed in my Haynes repair manual as 'Quad Driver module circuit'.(Codes 26 through 29 are all quad driver circuit, and that's all the book says on it too)

I've gone through the entire wiring and sensors, and the only thing I've found wrong is the oil pressure gauge is slammed to it's max position
I'm starting to think that the ECM is starting to go bad since the problem only occurs when the cars moving for a few minutes, and only occationally can I get the check engine light to come on while the cars parked.

I'm running out of time to fix the problem here ok, so I''m not beating around the bush here, so please, just tell me what you believe it may be, I'll check it out and confirm or deny it's the problem, and go from there. I'm just not interested in taking the car in to a shop and fork over a few hundred dollars for something I can fix for a lot less yet, so an answer that I really need is asked again:

What sensors does the quad driver module circuit #1 actually monitor, and what pin do I need to check on the ECM to test out the quad driver circuit to see if it's burned out or not?

Pontiac Bonneville 1988, 3800 engine.

Thanks for the responses Isussel. It's all a great help, but there is no sensor near the oil pan in this case for it's pressure. The sensor is on the oil filter mount, and yes, it is a bit of a pain to get to it. I had to take the passenger tire off, a cover, then eventually use a pair of vice grips to get the sensor off (I was gentle doing it too). Also checked the wiring, end to end, and it all seemed to check out ok so far.

I still need to know what the Quad #1 sensor is connected to and monitoring, as it may help me find the real problem faster, or maby even indicate that the ECM is indeed going bad with the Quad itself.

The old oil sensor WAS bad btw, and the new one does almost the same things as the old sensor, regretfully though, it's the WRONG sensor, so Saturday here I'll be getting the right one, and post how it acts as compaired to the old sensor (for right now, I put the old sensor back in). I'll also rip into the kick panel area housing the ECM and test out a bunch more connections there to maby help rule out a wiring problem too, as well, check at some junk yards in the area here and see if I can get a hold of a different ECM and duplicate the codes and such too, it's just right now we're so limited on time and cash to work on it. I guess that's what a shade-tree mechanic gets with a wife that likes to put things off till the last minute. LMAO. She'll sing a different tune if the car can't pass emissions in about 2 weeks.

I'll post sometime Saturday afternoon with all the rest of my findings since the wife will be using the car Friday for work (only about 3 miles 1 way for her).
OH, and so you know, we're using the car as little as possible. Riding a bicycle 6 miles to and from work makes life a bit interesting at times for me.

Oil pressure appears to now be working normally after getting the correct sensor for it. Runs just below half way up the gauge (about 35 psi at idle).

Couldn't get a different ECM to work Saturday. Was interesting looking through junkyards all morning though.

One thing that makes this problem a lot harder is that the ECM in the car has been remanufactured, and they took off the original stickers that were on it. But, 1 place I called to happen to have 2 out of 3 ECM's that can go into the Pontiac 88 Bonneville, so Monday after work, I'll go check them out, try them and see which one is the closest match in this case. (My area, places are closed by about 2PM on weekends, or not even open at all)

Tried a different ECM, and got the same code 26.

MORE:

Have talked with a mechanics friend`, and he referred me to the following:

1. Evaporative purge unit
(no smell of fuel. Voltage test to compair to would help. Appears to operate correctly)
2. Throttle position sensor #2
(sensor replaced. Running at.8V for low sensor check to cancel code 22)
3. Air/fuel ratio/malfunction
(O2 sensor operating within parameters or it would produce code 44 or 45, lean/rich considerig)
4. Quad driver sensor 2
(RULED OUT as that would cause a code 27 to occur)
5. Right front wheel speed
( By wiring schematics, appears to be only 1 sensor for speed, and it appears to work normally, because if it wasn't, then the spedometer would 'bounce' around. It does not)

For now, have to wait till tomorrow to replace the Neutral Starter Safety Switch, which may possibly be the problem. I myserlf here, forgot about totallty since it started to work correctly when the temperature got above 40F.
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