1998 LS400, my pride and joy. I was using a code scanner (Zurich OBD2 Code reader - borrowed from a friend) to clear a code. While using it I checked battery status - "good". Decided to check alternator status and when I selected "alternator" there was a click/pop not sure in retrospect and then all went black. Care behaves as if there is no battery - no horn, no light, no getting car out of park... like the battery is gone. Will take battery to auto zone tomorrow to check it, but I suspect it's fine. Any ideas on next step would be greatly appreciated.

 

Alternator fuse is blown? Don't know exactly where it is look for a white fuse with clear cover. This is fuse is bolted in!

 

thanks for the quick reply. I thought same -fuse of some sort . I did find and look at the alternator fuse, nothing obvious, but did not take it out yet. Also thinking, even with a bad or even absent alternator/alternator fuse, I could get a little juice for awhile - this car went immediately dark - no electricity at all, like somebody flipped a switch

 

Loosen then tighten the battery terminals.

 

yes did that, even tried to jump it - no love. Battery out now and will get it tested, but not anticipating it is the problem

 

check fuses and fusible links.

 

I would have bet my life it was the main battery fuse, so much so that I shopped for a replacement and returned home last night ready to replace the fuse. But when I checked the fuses and fusible links, they all looked intact.

Having been around long enough to know that many problems in all things electric, everything run by a computer, and most things with safety measures embedded, can be remedied by unplugging and replugging the device, I reconnected the battery.and tried to restart the car. It started up perfectly and runs like a dream.

My conclusion: the scanner triggered the anti-theft emergency car shut down protocol and apparently, leaving the battery disconnected for 24 hours resets everything.

Years ago, many luxury car manufacturers like Mercedes, BMW, Lexus... had an anti-theft measure that when triggered, shut down all electricity to the car. This is no longer used because it was quite inconvenient. If triggered, owners had to have their cars towed to the dealer, who then probably charged $$$ to "re-boot" their car.

I'm not a mechanic, so if someone has a better explanation for what happened, please let me know, and thank you all

 

wow this is a first i heard about this. i thought the anti-theft would disable the starter from engaging at all but kept all the electricals intact. perhaps yamae has more insight to this!

glad it was a simple fix for you!

 

There is no master kill switch feature on these cars.

 

Thanks - I have no other explanation for what happened. If someone has another reasonable explanation I'd love to here it. Otherwise, i will continue to drive in blissfull ignorance.

 

I think it's the Galvanic corrosion related problem as is explained here. Dissimilar metal contacts causes the problem. The anodic index of lead used for battery posts is -0.7V as is shown in the table below. On the other hand, Toyota's battery terminals show around -0.5V or so. There exists the voltage difference of 0.2V. The value 0.2V does not cause the corrosion problem quickly but it sure causes when contacted for many years.

Some aftermarket battery terminals use bronze which shows -0.4V, some copper-nickel alloy -0.35V. These show bigger voltage difference against lead and the corrosion starts quicker than the Toyota/Lexus genuine battery terminals.

So, it is not a smart idea to use aftermarket terminals. Even you use genuine ones, you'd better to polish the surface time to time to prevent the corrosion problem.

 

Galvanic Corrosion, I like that, but would it cause an instantaneous loss of electrical power that is restored by reconnecting the same battery to the same terminals 24 hours later. I’ve owned this car since 2000, terminals are the originals and clean. Maybe the previous owner installed a kill switch?
I’m just happy it seems to be fine now and do appreciate any and all potential explanations