Hey Rob,
Well I said I'd let you know how I got on. It turned out to be the pre-amp thatwas cutting out, but the head unit was still taking power. pre-amp has been replaced as has the aux battery (45ah). Not having any problems at all, but will let you know if it satrts to reocurr.
Hi Malcolm
If you read through all the postings on this problem, you will fall asleep
In a few words.
Check your starter battery capacity on the battery label ? Is it 40ah or 70ah ? Mine was a 40 ah and I got it changed to a new 70ah as a warranty.foc. Also check your sun visors .. On the RX300 if the mirror is not closed securely, the light stays on. The car requires a deep cycling/starter battery around 90 ah ... I have discovered that a Elecsol 70 will fit the tight space with a little bit of persuasion. This is a deep cycling/starter battery (albeit 70 ah) I have ordered one and I'll post back on here how I get on (If it arrives soon through the snow.) In a nutshell all the poxy batteries fitted by Lexus are to small in the ampere hour capacity department to handle all the toys on these excellent cars if the car is stored for longer than a couple of weeks. Regards Roy