94 Lesabre - Code 1650 QDM2 failure, weird problems...

My car's been having some strange problems. Sometimes when I accelerate, the car will hesitate and the change oil soon light comes on. I have to wait for the light to turn off before I can accelerate again. If I push the car too hard, such as pass another car while going up a hill, it'll completely stall. The oil level is okay. I thought that it might be a fuel problem, so I changed the fuel filter, but it didn't make a difference. I brought it in to a mechanic who pulled a code 1650 from the computer, indicating a QDM2 failure. He checked the car's computer and it was okay. He recommended that I bring it to a transmission shop where they have a mechanic who used to work at a local GM dealership. Supposedly, the mechanics at the dealership had seen this problem before on similar cars.

Has anyone heard of this problem before?

In the meantime, I'm forced to drive like an old lady...

The qdm drives certain high load solenoids such as the TCC, egr solenoids, evap solenoid and several others, one is overloading the driver and the circuit in pcm opens for self protection, The faulty wiring or device in that driver circuit must be isolated and repaired .this may be related to recent work you had done.

P1650 = Driver 2 - Input High Voltage

A quad driver is capable of controlling four (4) different devices; therefore the name "Quad" was applied. The drivers are nothing but a switch in the PCM that sends a ground circuit to the device it is told to operate. Your “change oil soon” sensor, could be controlled by that same driver, hence the light coming on. I don't have a wiring diagram in front of me, but I would make a guess, that the sensor on your oil pan is also part of this driver circuit. If that sensor is disconnected or has failed, or if it indicates an overload, the quad circuit can not be completed, therefore a code will be given. Max is right by saying, “The faulty wiring or device in that driver circuit must be isolated and repaired”.
Also, I wanted to mention that if the driver circuit giving the fault is related to the oil system sensors or pressure switch, that the PCM will go into "limp home mode" and or, open loop, to help protect the engine and force you to fix the problem. "Limp home mode" is like the engine running on crutches. I.e. it runs just well enough to get you home or the shop!

I just looked up the code in the official gm repair manual, and it appears that the qdm2 is hooked up to 4 solenoids (2 shift solenoids and 2 tcc solenoids) in the transmission... It's starting to sound like an expensive repair...

I just looked up the code in the official gm repair manual, and it appears that the qdm2 is hooked up to 4 solenoids (2 shift solenoids and 2 tcc solenoids) in the transmission... It's starting to sound like an expensive repair...

Not that bad, you are talking about 4 hours of labor and parts. All the solenoids are under the trans side cover .