It does return when i put the problem one back in, but i have ordered a newer one from a 2005 model, i hope they are compatible, i suspect if i had not read that US forum i would already be 500-1000 in the hole, 7 days garage time, 4 of which was Lexus and my dealer would have charged the full lot to find that.
There has been an alarm in the past but maybe with me dropping her off, the radio on and it also raining i just missed it, anyway not sure how much that contributed but you never know with shorts and electrics