2003 TL- mysteriously no power to anything- main/battery fuses appear good, 60A and 120A. This happened once before and the power mysteriously came back on, started fine and I drove the car for a week. This time I had to override the shifter using the console lever and when I did I got power for just a moment and it then went away.
I am a mechanic and know my way around cars pretty well but this has me baffled. I checked the battery terminals and they are tight. could the negative cable be toast and unnoticeable upon inspection; as in no longer conductive?

Any help is appreciated

 

irvin, maybe you can help clean up this sentence for me?

Does this mean, you got the car started by using the override shifter release/lock ?

 

Irvin58...

As a profession tech myself, my only suggestion is to get a wiring diagram of the electrical system on Mitchel 1...it should be under Engine Managment.

Trace out the power and grounds.....something is amiss. Maybe a ignition switch? But asking people to diag your car without actually being there to do the proper steps is no war to diag your car.

 

Yeah, there's nothing like actual wiring schematics to help diagnose a serious problem.
All we can do from here is guess.....the same as you are doing.

Download a copy of the "Factory Service Manual", as it'll be your best friend in times of need !!!

 

Sounds to me like Ignition switch.
Does it at least power the dome light when you open the door?
Check the main ground bolt for the ecu on the thermostat housing for corrosion or if its loose, should be clean and bolted down.

 

Yes, corroded ground cables cause trouble.
The Helm's manual is pretty good about diagnostics. Follow those steps...?

 

Even with the baddest corrosion there is actually low chances for a cable that thick to lose all conductivity even for basic things like open the ignition key or turning your parking lights should work ok..


As easy as: If you can turn all your Low Beams (HIDs) + Fogs + Highs then definitely you got power and conductivity to start the car..
If the car just doesn't power those (Even parking lights?) then I would check all my grounds first then look for main +12v cable...
If they power up then you ignition key should be your Number 1 suspect.