Got a 92 Lesabre when it is warm and you come to a stop and when you take off the tranny is in what feels like either 3rd or 2nd gear. Fluid was low a couple of days ago, topped it off and it is still doing it. Got the DTC from the computer
24 Vehicle Speed Sensor (VSS) Circuit
31 Park/Neutral Switch Circuit

I know the VSS plays into the torque converter but I'm not sure, I ordered a VSS from the dealer and will put it in tomorrow, I am also going to change the fluid as it has 80k miles on it and I'll bet it was never changed. Any other ideas what might be wrong or to check?

Make sure you also change the filter. Pay attention to the magnet and the pan. Post up pictures if possible. Look for any chunks or debris.

Thought I'd have heard a hundred responses by now, so today I put in the new VSS changed the ATF added a quart of that Risoline Slip/leak preventer, new filter and cleared the OBD codes. Test drive went well, nice and smooth shifting, sounds good, no new codes were set. However time will tell if that was the problem, as I stated in the original post this didn't happen all the time.

Steve is our transmission guy and I don't think he'* been on today. Lets hope it stays fixed for you.

Well the problem came back. I got the codes from the OBD and only the one
24 Vehicle Speed Sensor (VSS) Circuit
So to summarize, after driving for a while the car is nice and warm I am stopped at a traffic signal. Upon accelerating the car is in 3rd gear and is very slow to get up to speed due to the gear ratio. For some reason the transmission is stuck in 3rd gear and did not return to 1st upon stopping at the light. So I have already replaced the VSS sensor, fluid, filter. This has not remedied the situation. Any thoughts???

I have found that there were these TSB issued, does anybody have access to these Technical Service Bulletins (TSB) ? I am very interested in the first one issued in 1992

NOVEMBER 1992 SIR - Revised Diagnosis Intermittent DTC 24
OCTOBER 1992 SIR System - Revised Code 24, 25, or 26 Diagnosis
AUGUST 1994 SIR DTC 24 Diagnosis

My son drives the LeSabre and I told him to wiggle the column shifter if the problem reoccurs, if that doesn't fix it to start by putting the shifter into 1st gear and see if that forces the transmission into 1st gear. He said he tried it and it worked. So I am now looking at the Park/Neutral Switch Circuit (PRNDL switch) as the problem, however it isn't clear to me why or how this switch would force the transmission into high gear at a stop? I'm reluctant to change the switch, any ideas?
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Found out some new information, apparently when a DTC 24 is set the PCM only allows 2nd or 3rd gear to function, found this in either the Mitchel manual or Alldata.com can't remember. Anyways I am thinking now what would cause a VSS DTC 24, I replaced the VSS already, possible a bad ground or frayed wire. The diagnostic says indicates bad wire, bad PCM so that is where I am now, going to look at all the wires. Anybody have any ideas?