a model number may help

1. Try cleaning the sensor bars inside the drum with vinegar or alcohol. Heavy use of dryer softener sheets can coat them with residue interfering with proper functioning.

2. Try setting the machine slightly off-level toward either the front or back, depending on where are the sensor bars (at back of the drum, or in front under the door opening). That may help small loads keep in contact with the bars.

3. Slight chance that a wire has come off the sensor which would have the effect of it sensing no moisture and the cycle would run for only minimal time. This is rather unlikely, and you'd have to disassemble the dryer to check. If the machine has an electronic control panel, there's probably a diagnostic routine to check whether the sensor is working properly. If you're "handy" with household repairs and such you might try getting into the console (try removing the back panel of the console if that looks like a way in), check if there's a Tech Sheet inside which outlines the diagnostic procedure. Or post the FULL model number here, maybe someone can give you instructions.

4. 7.5 cu. ft. is a large drum. If the dryer is functioning correctly and you're going to be routinely drying small loads, you just may not be able to get much use out of the auto-dry cycles. They typically really do work better with medium- to full-size loads.

Sure. The model number is 110.60942990. It's a Kenmore Elite king-size capacity.
Someone just suggested putting it slightly off-level so the clothes tumble against the sensors more often, and I'm going to try that. I just checked it with a level, and it's tilted in exactly the wrong way to maximize contact.

Dadoes,
The off-level suggestion is just brilliant -- thanks! I'm going to try it ASAP!

I did clean the sensor bars, and I pulled out the lint filter and vacuumed out the area it fits into; got a lot more lint out that way.

I also thought it was unlikely a wire came undone, but I may be able to get a handy friend to check that for me. Since it did work better with a medium sized load, I think the wires are probably okay.

I guess I learned a lesson -- I don't need a big dryer. The few times a year I do blankets or comforters, I can go to a friend's house. Who knew this would be a problem?! This just isn't publicized, that a moisture sensor doesn't work with big loads.
H.

sensor #34 (top center) behind #23 OUTLET HOUSING ASSEMBLY (front of dryer behind #64 LINT SCREEN)

11060942990 BULKHEAD diagram

I see from the parts diagrams that it's Whirlpool's 27" dryer design, same as my Calypso Senseon dryer. It's a sturdy mechanical design, the drum has roller supports both front and back, unlike some dryers that have rollers in back with nylon or felt glides in front that don't last as long. However, the drum is very deep front-to-back, which gives small loads a lot of "elbow room" to tumble without contacting the sensor bars at the front. It has mechanical controls, not an electronic panel, so there are no built-in diagnostic routines to test the sensor*. There is a small electronic board for the moisture sensor circuit, which is likely OK since it dries OK with larger loads.

Question: It really shut off in just five mins with a small load? That's a little unusual for a mechanical timer. Even with the moisture sensor basically signaling a dry load, the timer has to physically run the distance from the initial setting to Off, which should be more than 5 mins. For small loads, try setting the timer more toward the Very Dry or Extra Dry end of the scale, maybe even at the extreme end. That may work out for small loads to come out "normally" dried.

Or is the diagram wrong and it does have an electronic panel?

*There is something you could do to test the sensor, that may or may not work. If there's a separate temperature control to select Air/No Heat, *with* the timer on the auto-sensor cycle, you could run it with the door open, pressing the safety switch to override it, and hold a damp cloth against the sensor bars which should prevent the timer from moving. Remove the cloth, and the timer should move. It'd take several minutes holding the cloth both ways to visually confirm the timer is or is not advancing. HOWEVER, you'd have to be SURE that the gas burner won't come on running with the door open, because with the door open the airflow is wrong (pulled in through the open door instead of through the burner duct) and would cause it to overheat, possibly blowing the thermal safety fuse which would then have to be replaced. This won't work if Air/No Heat is a separate TIMED cycle on the timer, or if selecting Air on the temp control bypasses the moisture sensor circuit so that the effect is a timed cycle even on the auto-dry setting.

Dadoes,
Yes it really shut off in 5 mins with a small load -- I could actually SEE the dial on the timer moving. That said, my first test load was very tiny -- I live alone and tend to have small loads of laundry.

Last night I gathered together a load of (clean) towels and sheets and washed them so I could test the dryer on a large load. It seemed to work fine on a large load.

I can't do the test you suggest above, because air fluff is a timed cycle only. But as soon as I can get a friend to help me, I'm going to readjust the feet so the dryer tilts forward a little, hopefully helping clothes contact the sensor.

The weird thing is, this didn't happen w/ my old Kenmore. I think it must have had one of those exhaust sensors (instead of the sensor bars in the drum) because I could use the sensor cycle on just one sweater and it worked fine.

I only paid $50 for this from a neighbor who was moving. It didn't occur to me that the king capacity would be a problem; now I know and will spread the word. I can always sell this one again, probably getting my $50 back and start over -- but I'm inclined to just make do for awhile.

Yes it really shut off in 5 mins with a small load -- I could actually SEE the dial on the timer moving.That's good! Means the mechanical timer on non-electronic moisture-sensor units has been improved to being comparable to those with electronic panels ... or at least your particular model has. :-)