One morning a few weeks ago wife's car would not start. Battery was near five years old so without hesitation I replaced the battery with a new Group 24F battery. Problem solved. Car started fine and no further issues.
Now one evening my wife goes to drive it and car won't start. I check the battery and it appears to be okay. I hook up the battery charger for overnight and next day still no start. Now this has my attention. Battery check show voltage is at 12.6 volts after the charge. I put the key in ignition and turn key to ON position and this time I notice the dash lights are not on. Only the red seat belt light and amber/orange check engine light are on but not the dash lights. Further turning the key to the start position does nothing. No clicks, no buzzing no starter drag, just nothing. Further check show the following have no power - radio, fan, windows, seat. The power door locks still work and the remote key door lock/unlock function for key still work. The headlights still work. Didn't check brake lights yet. So I removed the neutral start safety and push button to put the gear selector into neutral and still nothing. Or any other gear selection is still nothing.
Watched a few youtube videos and decided problem was the ignition starter switch as this has all of the symptoms, or so I decided. So now I have it switched out with a new made in China switch.
Still same problems. Didn't mention I checked out all fuses and they are okay but the cigarette lighter fuse (15A) that I was aware of. Have not verified any relays as of yet or any wiring. Battery terminals are cleaned from doing the battery change and never any corrosion.
Car is well maintained with 86k miles and still runs, drives very well with no reason to replace it.
Any thoughts or suggestions or past experience with this issue is welcomed.

 

 

Did you try a different key?
Does the car have an aftermarket alarm or remote start?

 

I have not tried a different key. It was lost a few months ago and not replaced yet. While searching for this "no start" issue I read some info about some software called Techstream to program my own key rather than dealing with a Lexus dealer and those prices that go with it.
No after market stereo or remote start. ALL wiring is as it came from dealer new.

 

Testing the terminals for tightness and see they are snug and look to be in great shape. No corrosion and I have those anti-corrosive pads underneath with a dab of anti-corrosive dielectric grease I use for all my electrical connections similar to this.

 

 

 

 

This is what the Alternator 120A fuse looks like before and after I pulled out that piece of wire. Turns out that is a short piece of a fusible link that was done before I purchased the car nine and half years and 65k miles ago. All I did was put the fusible link back a more secure then before and this will solve my problem until I do a proper repair and replace it with a correct 120A fuse.
Thanks to all your replies as it is always helpful to hear another persons opinion.

 

Replace with the correct fuse ASAP a high current fuse that is shorted can cause a fire and literally burn your car to the ground.

 

Wow that is scary!! Why would someone rig a high amp fuse like that when they are so cheap to just replace. Not worth the risk of burning your car to the ground. Replace that fuse ASAP!!

 

Because replacing that fuse is a real PITA. You have to pull the whole fuse box and release the fuse from underneath. They were lazy, not cheap. Doesn't justify it, just explains it.

 

I have watched a few videos on replacing this fuse on Lexus and Toyota's and it does appear to be a really difficult process, but still doable. As I said before, this fuse was replaced before I purchased the car nine and half years ago and no problems until now. The wire is not just a scrap piece of copper jammed in the hole but it is a 100 amp fusible link. A fusible link is a short piece of insulated low-voltage cable within an automotive wiring harness that is designed to protect the harness in applications where a fuse is unsuitable.
My short term plan is to replace the fusible link with the correct fuse. When I do, I'll be back with an update and picture.

 

120amp alternator fuse replaced and all is well. Just a note that during the separation of the fuse panel, I used toothpicks to release the locking tabs. So much easier than I was expecting.

 

What does the nav screen show for hybrid battery charge, how many bars?