The Teamsters and the trucking industry resume negotiations here today with little expectation of a quick end to the contract dispute that has shut down most of the nation's major trucking firms since Sunday.

One source close to the bargaining said the talks are likely to stretch into next week - or longer - as the two sides continue to assess the impact of the industry's lockout of the Teamsters union.

This means there could be a spread of economic disruption, which has so far been confined mainly to the auto industry, before pressures build sufficiently for a negotiated settlement or government intervention, sources said.

Government officials, including Labor Secretary Ray Marshall, have said that little, if any, disruption in the movement of critical commodities such as food and fuel is expected before a week at the soonest, possibly two.

The lockout, or "defensive shutdown," as the industry calls it, was called by the industry bargaining group within hours after the Teamsters declared a selective strike against 73 individual firms when their contract expired without agreement on new terms.

Industry sources claim the lockout extends to nearly 500 firms employing 235,000 of the 300,000 Teamsters covered by the master freight contract. But Teamsters President Frank Fitzsimmons has said the industry claims are exaggerated.

Trucking Managmement Inc., the industry bargaining group, held what was called a "solidarity meeting" on Tuesday, and the Teamsters held a similar session yesterdary in Chicago. The relative moods of these two meetings would indicated where the the presure points will be in the new round of negotiations, but the answer is not likely to be known until today, if then. One source said yesterday that it looks like a stand-off so far.

Meanwhile, the government has moved to ease some of its own obstacles to a settlement. Marshall indicated Tuesday the administration's wage guideline may be flexible enough to accommmodate Teamster money demands, and yesterday the Interstate Commerce Commission reissued an earlier statement that labor cost increases exceeding the guidelines must be "fully justified" to merit rate increases. An ICC aide said there had been misinterpretations implying that rate increases would automatically be held to the guidelines.

In Detroit, the auto industry reported that layoffs and short shifts, caused by parts shortages, continued to mount - reaching 121,000 workers, or one-sixth of the industry's work force. The Whirlpool Co. said it was furloughing 4,600 workers in Michigan and Ohio.

Although there has generally been little strike-related violence, Pennsylvania State Police reported two rockthrowing incidents and one shooting involving truckers, one of them driving a postal vehicle. CAPTION: Picture, Ford Motor Co.'s Rouge assembly line in Dearborn, Mich., was idle yesterday as the auto firm cut shifts in the wake of a trucking industry shutdown, after Teamsters started selective strikes last weekend. More than 115,000 auto workers were idled or put on short shifts as of yesterday, with Chrysler Corp. shutting all assembly lines, including Newark, Del. General Motors Corp. will lay off 4,500 of 7,000 Baltimore workers without a quick settlement.