Lexus RX300: ABS/ESP warning lamp illuminated

Question:

We are having difficulty diagnosing an electrical fault on a 2005 Lexus RX300 3.0. The ABS/ESP warning lamp is illuminated and some trouble codes are stored. We have worked through the trouble codes but haven't found the cause of the fault. Has this been reported before?

Answer:

Yes, this fault is known on this model and is due to water ingress into the ABS harness multi-plug via the heated windscreen wiring harness. First, thoroughly clean the area around the heated windscreen wiring harness at the base of the windscreen (see figure above).  Then, apply an appropriate sealant to the heated windscreen wiring harness. Check the condition of the ABS harness multi-plug, repair/replace components as necessary. Finally, erase the trouble codes and road test the vehicle to confirm that the fault is rectified.