First of all, I did search the forum, but as my problem seems to be really odd, I might not have read everything.

I haven't been using the car (95 LS400) for about a week. Today I went to start it up and I couldn't. Checked the battery, and it is alright (changed about 8 months ago btw).

Ignition in our LSs has 4 states, namely LOCK, ACC, ON and START. The lights on the dash light up when in ON usually. In my case it is a bit messed up and I have the real ON (when the dash lights are on) just between ACC and ON. When I turn to ON, the dash goes dark, and if I want to turn to START, nothing happens besides the clock turns off for that moment - just like when you have dead battery. This is second time I have this problem. The last time was in winter when it was about -25 Celcius. In that case unplugging the battery for about 3 hours did the trick. This time however the battery was unplugged for longer and still I cannot start the car. Any help would be appreciated.

 

Check the battery voltage under no-load AND load conditions (with the key in all the positions you mentioned (including START).
Potential problems (just pure guesswork at this point) -
Dash going dark when switch ON: faulty ignition switch (contacts)
Clock off when switch to START: If battery voltage stays relatively high (say 10V or higher), bad switch, solenoid contacts, or high resistance (perhaps open) in the starter motor windings, cables, etc.
If battery voltage goes low: bad battery, or high resistance to the starter motor turning.
You may also get some indication by observing the headlights during the procedure, but a voltmeter is far batter.
One other point - do you hear a click when you turn the key to START ?

 

sounds like you have a bad ignition switch, but check your battery terminals first if they are tight.

how did you check the battery? did you put a meter to it and get a voltage reading?

 

check those cables... that slender terminal is known to go bad after a while and needs to be replaced.

 

Thanks for the replies. I didn't have time today to recheck everything, but answering your questions:

@Gene01: I am not sure about the click. I do hear a click as I used to, when turning the key (while turning to ON and leaving there the key). I guess this is good?

@timmy0tool: I checked the battery by measuring the voltage between terminals with a meter. Also, at first I thought it was the dead battery, so I connected the rectifier to make sure the battery is fully charged. At this point I really doubt the problem is in the battery itself.

 

It may be anti-theft computer. Happened on my 99. I found that PUTTING THE KEY IN THE DRIVERS DOOR WITH ALL DOORS CLOSED and turn to the unlock position first and back to unlock 4 times ending back in the unlock position solved my problem. Lextreme.com has the procedure. Check it out...

 

Doc Yota, thanks for the info. I would definetely give it a try. Although it fixed itself for now, I know that it will come back any moment, so I want to fix it for good. Last night I had a flat battery, and knowing that I have an almost new battery this was weird for me. After recharging the battery I have found out that with everything switched off and car closed (as well as the hood) it takes 3 amps all the time, which to me is way to much. For now, I believe that both problems are somehow connected and my first thought is the anti-theft system. Is there any way to completely remove it. Would unplugging the anti-theft computer work or it's not enough ?

 

Three amp drain is way too much; you either have a light staying on somewhere, or a phantom load. Need to find it by isolating different circuits, pulling fuses, etc.

 

I can't find it right now, but Yamae (no surprise) posted the best method for isolating a parasitic current draw within the last year or two.

 

@fixmiester, I agree and this is why I will start by pulling fuses, but probably during the weekend. I will also check Yamae's post (hope to find it).

Anyway, thanks for any help and I will keep you posted if anything changes.

 

You have a good memory, Gene.
Without removing any fuse, there is a way to check a drain of 1A or more using a good volt meter or a multi meter which can read down to 1mV or less. You can find the post at #7 at below.
https://www.clublexus.com/forums/ls4...eps-dying.html

 

Thanks, Yamae-san. I am sure that this will be very helpful to the OP.

 

Fixed

My meter could not measure that little V, so I had to check the fuses one by one. With DOME fuses removed (2 of them), the current dropped from 3 to good 0.05 amps, which was a good start for me. I figured out that the rear passanger light (driver side, the one that lights up when the door is open) was all the time on, even with the car locked. Removing the bulb did fix the problem, yet it didn't fix the source I guess.
For now it is a good fix that lets me drive the car, but with a little more weekend time I want to check why the light was on. I am not sure, but it is not the locking door sensor, as the car locks with no open door sound nor the red light on the cluster stays on.

 

Good find and thanks for coming back and sharing..
Now to find out which line is not opening back up with all the doors closed to allow that little light to stay on...
Glad you found the source.

 

Glad the car is more useful to you. However, 500 mA still sounds a bit high to me. I would expect a drain on the order of 10 mA.