Lawsuits filed by some of the nation’s largest insurance companies have opened a new front in the litigation against Toyota Motor Corp. over claims that defects in its vehicles caused them to suddenly accelerate out of control.

Separate suits were filed on Dec. 30 by Fireman’s Fund Insurance Co., Motorists Mutual Insurance Co. and Ameriprise Insurance Co. The cases collectively seek nearly $200,000 — for starters — in damages, alleging that Toyota failed to warn about vehicle defects that caused 14 accidents for which the insurance carriers were forced to compensate claimants. The suits came three months after Allstate Insurance Group sued Toyota for $3 million on similar ground.