Mr. Innovator

Had this same issue with my 95 LS 400, my friend who is a Toyota line mechanic thought the crank position sensor was going out,or near. Turns out it actually was the fuel pump, with the back seat removed and the key in the on position the pump would quietly hum but would do so intermittently it would seem to pressure up then fall back and create a crank/no start condition, then pressure up and stay there. Since the back seat was already removed, I replaced the fuel pump, (which was relatively easy even with basic mechanic skills) its been trouble free since then. As to your key being or having a chip in it, (I’ll assume not) as mine is a year newer than yours and was scanned 2 weeks ago by a licensed locksmith and found to not have any chip in the (2) factory Lexus keys that came with my car.

Hello to all LS 400 owners:I’m new to this forum so bear with me as I stumble through it. I have just completed replacing my Lexus LS400 factory radio (non Nachamechi) with a newer double din pioneer head unit, everything is working great except the power antenna will not raise once the unit powers up. Pioneers website lists a dedicated ignition wire that triggers the antenna to raise the moment the ignition key is turned on ( which I had already done) I can hear the antenna motor activate but no action on the mast, thought maybe the internal plastic gear tape had stripped out inside the antenna...but it appears fine. Any suggestions on a fix?