DETROIT (AP) _ The Big Three automakers' combined domestic car and light truck sales rose 11.2 percent in late October from a year ago, indicating last month's stock market shakeup may not have hurt the auto market, the companies reported Wednesday.

General Motors Corp., Ford Motor Co. and Chrysler Corp. together sold 318,133 domestic passenger vehicles during the 10 selling days from Oct. 21-31, up from 286,071 during the same period a year ago.

The automakers' reports for the last sales period of October had been awaited as one of the first measurements of the effects of the stock market's spill on consumer confidence and demand.

Ford Vice Chairman Harold Poling said Wednesday that consumer demand was recovering with few ill effects and Ford has no plans to cut its 1988 vehicle production schedules.

''At this time, I'm encouraged by the results in October. The underlying economic factors are still the same as before the crash,'' Poling said, pointing to falling interest rates, low inflation and low, stable fuel prices. Big Three car sales fell a slight 0.6 percent 196,015 from 197,145 a year ago, while light truck sales jumped 37.3 percent to 122,118 from 88,926 a year ago, the automakers reported.

The domestic sales totals do not include imported cars all three companies sell under their own nameplates.

Ford's domestic car sales rose 12.6 percent, to 59,603 from 52,844 a year ago. Ford's light truck sales were up 56.7 percent, to 47,637 from 30,398 in late October a year ago.

Industry-leader GM's domestic car sales fell a relatively slight 5.8 percent, to 103,777 from 110,141 a year ago. In domestic light trucks, GM's sales were up 33.1 percent, to 46,115 from 34,641 a year ago.

No. 3 Chrysler suffered only a 4.2 percent decline in domestic car sales, to 32,736 from 34,160 a year ago. Both Chrysler and GM car sales have trailed 1986's levels throughout 1987.

Chrysler, which bought American Motors Corp. in August, sold 28,366 domestic light trucks including Jeep Corp. vehicles, up 18.8 percent from 23,887 a year ago.