retroscept

Hey everyone! This is my first post, but I’ve lurked on club lexus many times to fix issues with my 99 LS400 in the past. In fact, this has easily been the most problematic car I’ve owned! I can’t find any info on the exact symptoms I’ve experienced, so I’m reaching out for some help.

My LS400 would crank but refuse to start when trying to leaving the gas station last night, I had no issues getting to the gas station. It would crank for about 5 seconds, finally start, run for a few seconds, all the gauge lights would turn off, then it would slowly stall out.

I checked the ignition fuse and it was blown, I replaced it 3 times and it blew every single time when I turned the key all the way to the right. Even with the ignition fuse blown/removed, it would still crank, sometimes start, and stall out.

I did some research on here and other forums for about half an hour, came back and tried to start it again. It cranked instantly and ran normally… for about 10 seconds, then died instantly; no stalling or sputtering.

After that, it refuses to turn over more than once or twice and just gives up. It will not start at all. It’s no longer blowing ignition fuses and looks like the fuse is getting less than normal voltage.

I picked up an aftermarket ignition switch from Oreilly’s, the only other post I could find about the ignition fuse blowing was related to the switch. I wasn’t able to get the steering column down and out of the way to get to the switch, so I’m not sure if that’s the issue yet.

I also tried finding some ignition fuse wiring diagrams online with no luck.

Any kind of help would be appreciated, I’m supposed to be taking this car 5h north next weekend for a show.

CLLEXUSS

If your car has been easily the most problematic car you ever owned there's a high probability it had to do with whoever owned it. The person who owned my car previous to me literally reversed the polarity after she let the battery go dead, she decided to try and jump start a dead battery and had the cables attached and reversed polarity. And this was like about a decade ago when the car had not even 40K miles on it, she didn't drive it that much so the battery got weak after months of sitting. (you should never jump start these cars anyways, especially with a dead battery). So, she ended up taking it to the dealer and they combed through everything.. all the wiring, to all the fusible links, to the grounds, and flashed the ECU. So, more than 100,000 miles later the car is still fine after it was all sorted and fixed properly by qualified trained technicians.

CLLEXUSS

So I guess what I am trying to say is this is not and easy thing to diagnose over the internet but who knows, keep the thread alive and maybe we can figure it out.

aptoslexus

IGN fuse is the fuel injection circuit as well as the airbag system.

retroscept

Hi! Looks like it was the 30a ignition fuse under the hood that also blew, I never checked it. I swapped it out with a new one and it started and ran normally.

However, on the way home something kept shorting out and intermittently shutting off the car, usually when I hit a bump. Sometimes it would recover and continue running, sometimes I had to restart it in nuetral while driving. It sounded like metal banging together or something sparking every time it happened, so something is definitely making contact with something else and it shouldn’t be. Figured I forgot to secure a terminal, but they were indeed secure.

Anyone know how to diagnose electrical issues like this? I figured I’d just leave the car idling while on jack stands and wiggle any loose harnesses until I find something.

retroscept

Update: I killed a relay at some point and it drained the battery while I was sleeping. Woke up and checked on the car, dead battery and a lot of clicking coming from the fuse box.

retroscept

Figured it out, I rubbed the wire harnesses under the fenders and exposed a bunch of wires that started touching. Turns out you're supposed to tuck those when you go low, thank you guys for the help!

ccconor

Sorry to jack the thread, but what do you mean by you should never jump start these cars? My LS dies pretty often and I jump start it atleast twice a month. What damage am I causing?

Yamae

The surge stresses may cause multiple problems as are explained here as well as damaged rectifiers in the alternator. I find many cars having problems after the jump starting at shops where I often help. Toyota uses good surge suppressors and I find the failing ratio is not as high as other cars like Europeans but there sometimes come in Toyota cars. You'd better to use a jump starting cable with a good surge suppressor.