WASHINGTON - Federal safety officials have opened an investigation to determine if there is a defect in some Cadillacs that causes the cars' side airbags to deploy when they should not.
The National Highway Traffic Safety Administration said it received six complaints about side airbags in 1998-99 Cadillac DeVilles that deployed without crashes. It said people were bruised in three of the cases.
General Motors spokesman Greg Martin said the company is cooperating with the investigation, but he had no more details on the incidents.
NHTSA said 184,000 vehicles would be affected if the agency were to find a defect and order a recall.
In two other cases, the agency said it is intensifying investigations of DaimlerChrysler vehicles. The cases are being upgraded from what the agency calls preliminary evaluation to the more serious level of engineering analysis.
One invo lves 1994-96 Dodge Ram pickups. Nearly 700,000 of the trucks are in service.
NHTSA and the company have collected 275 complaints about problems in and around the trucks' ignition switch. They include reports of heat, smoke, melting plastic and fires. Other owners complained about illuminated warning lights and difficulty starting.
The agency said the root problem seems to be excessive current draw through the ignition switch when the blower motor is running. The company made some design changes during the 1996 model year and has a repair kit available for owners who have problems.
But NHTSA said it still needs to determine if the potential for fires constitutes a safety defect and if the problems could affect airbag or antilock brake systems.
The second DaimlerChrysler case upgraded by NHTSA involves 1997-98 Chrysler Cirrus and Sebring, Dodge Stratus and Plymouth Breeze cars. The agency and the company have received 62 complaints about floor mat material becoming entangled in steering columns and impeding driver control.
About 400,000 of the cars are in service.
NHTSA also intensified an investigation of headlight failure in 1995 Mazda Proteges, of which about 77,000 are on the road. The agency and the manufacturer have gathered 60 complaints about the problem.
NHTSA said the headlight switch is on the turn signal lever, and use of turn signals appears to cause wear and sometimes breakage of a wire in the headlight switch.
The agency said there have been more than 4,600 warranty claims related to headlight switches alone or headlight switches and turn signal levers together on 1995 Proteges.
NHTSA said it closed two investigations because it found insufficient evidence of safety defects. The cases had stemmed from complaints about the following:
Ruptures of right front brake hoses on 1992 Ford Aerostars.
Loss of throttle control in 1997-98 Ford F-150 pickups.
Escaping fuel from 1998-99 Ford Motor Co. vehicles equipped to run on compressed natural gas, including the Crown Victoria, F-150 pickup and E-350 van.
NHTSA said it opened the following new defect investigations:
1997-99 FORD EXPEDITION, 1998-99 LINCOLN NAVIGATOR
Problem: Towing hitch mounting bolts come loose.
Vehicle population: To be determined.
1997-98 BUICK PARK AVENUE
Problem: Front seat belt webbing bunches and binds in retractor guides.
Vehicle population: 125,000.
1995-96 OLDSMOBILE AURORA, BUICK RIVIERA
Problem: Rear seat belt retractors fail to keep webbing tight.
Vehicle population: 130,000.