One problem related to front seat belt buckle assembly has been reported for the 1999 Lexus ES. The most recently reported issues are listed below.
On or about October 22, 2007 the driver's seat belt on 1999 Lexus Es300 would not buckle as the female(console side)part of the seat belt would not return all the way up -the red button remained part way down. It was replaced with a Lexus part no. 73240-33010-a0, belt assy, frt st ,by the complainant and upon examination of the removed part , a broken off piece of red plastic similar in nature to that of the buckle release was caught in the assembly. When the piece of red plastic was removed from the assembly, the latch(buckle) again appeared to be working normally. This failure rendered the vehicle unsafe to drive until it could be replaced.