One problem related to brakes failed has been reported for the 2003 Lexus GS430. The most recently reported issues are listed below.
Total brakes failure twice. Dealer was not able to identify problem the first time and the brakes were working again after a few shutoffs/restarts of the engine. The second time, dealer claimed that it has located an "open circuit in pump motor" - many parts were replaced at $2,550. 53.