2008 Lexus.
IS350
No codes.

Get in. Sit down. Push brake pedal. Push start button. Dash lights up, all guage needles do the sweep movement.....but then the engine doesn't spin.

Battery good.
Starter good.
All electrical good.
No blown fuses.
Key fob is good.
Park/Neutral safety good.

I can force the starter to spin the engine if I "hot-wire" the starter solenoid
Two months ago I had a similar situation. Back then, I had no communication with the PCM and the wires for the Fuel Pressure Sensor and the Mass Air Flow Sensor had grounded out on each other. I insulated the wires. I replaced both sensors. Car ran fine after that.

What should I check/test?

Prior to this current no-start situation, the engine had failed to start on three separate occasions within this past week.

Also, I noticed that rather than firing up immediately, the engine seemed to need to spin a half second (or more) longer than it normally would before firing up.

 

What caused the damage to the wires creating the problems listed and how confident are you that everything was resolved?

This is where bracketing comes into play. An example is mice, a fire, and/or mechanical incidents causing damage that was not originally detected and corrected. Then there is the impact of latent failures caused by shorts and opens to electronics which is also a potential.

Hopefully its somerhing missed during the original investigation and repair.

 

Very confident that the original problem (a couple months ago) was resolved. That situation occurred due to mice chewing on wires causing two wires to ground out against each other. I paid a pro shop to diagnose the problem. I performed the recommended repairs.

I got the current situation narrowed down to a (possibly) bad starter solenoid. The problem is intermittent which caused me to believe that the starter is good.

So, when the starter failed to spin, I eventually tested the solenoid wire with a power probe tool. I pushed the starter button with my probe hooked up to the starter solenoid and the probe tool would light up for 5 seconds, then off. This let me know the solenoid is getting power.

A friend suggested I bang on the starter solenoid......such a stupid idea!.......But I hit it anyways and the engine fired up when I pushed the button. WTF!

So, I bought a new starter.

Tomorrow I am going to remove the starter from the car and disassemble the solenoid to take a look at it. If the solenoid appears undamaged I intend to clean it, lube it with dielectric grease, put it back together, install it on the car.......see what happens.

If the solenoid does infact show signs of damage, I'm going to replace the solenoid/starter assembly with what I bought today.

Retail auto parts store starter $150.
Lexus dealership OEM starter $569.

I bought the dealership unit.......I figure since the original Toyota starter lasted 15 years, I may as well spend the $$$ & replace it with an identical factory part.

 

OP here with an update:

I removed the starter from the car.

I pulled the solenoid off the starter.

Lots of gunk inside the solenoid body and lots of gunk on the solenoid piston.

I cleaned both the solenoid body and piston.

I lubed both the solenoid body & piston.

I put everything back together and the starter operates properly every time.