Goesta

Hello.

I know almost nothing about electrical systems in cars so please help me. I left the door open on my 1994 LS400, and the battery died. So I tried to jump start it with a battery charger/jumper thing, but I didn't realise that the charger/jumper was set for 24 volts instead of 12 volt. I tried starting it twice this way, before realising my mistake. The starter (I assume) made a clicking noise. After that I tried jump starting it with another car. The starter is going and sounds normal but the engine is not firing up. Did I fry the ECU or something else? Or is it just a fuse?

Yamae

The ECU is designed not to be killed easily and the possibility is low to be dead by your way. Your battery may be over charged and the ESR is too high to work properly. I'd try to check all fuses first and then I'd use a new battery after the old battery is disconnected for more than 12 hours to eliminate stray electrons in the different computer units.

Goesta

Well that's good news, thank you! I found a blown EFI fuse, which would explain why it's not firing up. I'm getting a new battery tommorrow and hoping for the best.

Goesta

Hello again. I removed the old battery for more than 12 hours, checked all the fuses, only EFI fuse was blown so I replaced it. Put a brand new battery in, and the same EFI fuse blows again. Did I break something that the fuse is supposed to protect? Like fuel pump or o2 sensors or anything else? Any ideas?

Yamae

The EFI fuse supplies the +B power to the ECU and the fuel pump via the EFI relay. The next step is to distinguish which side is short-circuited.