DaimlerChrysler and Dana Corp. are investigating a loud humming noise in some 1999 Jeep Grand Cherokees.
The noise is caused by a ring gear and pinion gear in the front axle that do not mesh properly. The gears relay torque to the front axle.
Dana, based in Toledo, Ohio, makes the axles.
'Anyone experiencing these problems should visit their local dealer, where the vehicle will be evaluated and repaired as necessary and under warranty,' said Bryan Zvibleman, a DaimlerChrysler spokesman in Auburn Hills, Mich.
Complaints have come from owners who have driven some of the early units assembled at the Jefferson North Assembly Plant in Detroit, he said.
DaimlerChrysler does not know how many redesigned Grand Cherokees are affected. Dana is working with DaimlerChrysler to determine why only some Grand Cherokees are affected, said Dana spokesman Gary Corrigan.
'It's not a safety, driveability or performance issue,' he said.
It does not occur on all new Grand Cherokees, so an analysis is being done to determine the variables that cause the hum, Corrigan said.
The redesigned 1999 Grand Cherokee went on sale in August, after its first major overhaul since its introduction in 1992.
The ring gear and pinion gear in question have curved teeth, and if they do not mesh properly, 'you can get a whining type of noise,' said Al Motta, a DaimlerChrysler customer advocate manager in Auburn Hills.
Service personnel at the dealerships will realign the gears to eliminate the noise, he said.
'It's a very subjective thing,' Motta said. 'None of this will generate a failure.'