LS400 accidental 24 volts

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New Member

I have damaged the electrical system in my 1994 LS400, and I'm struggling to figure out the source of the problem. My knowledge of the electrical system in a car is basically non-existent. The way it happened was I left the door open, so the battery drained. Later when I tried to jump start the car, the charger was set at 24 volts instead of 12 by someone else, which I didn't notice until it was too late. So dumb.

Now, when I try to start the car, the EFI-fuse blows every time, so my very limited knowledge tells me there's a short in a component or wire behind that fuse. Any suggestions on what it could be? Maybe several things? I would really appreciate any help!


New Member
Will it be best to contact a car mechanic then? If you don't have the knowledge to fix the issue then you will have hard time fixing the problem.


Some where down under
Your description of yourself is more accurate than what you have provided about what you did.
Was the battery connected when you attached the battery charger and attempted to jump start the car. If so, its unlikely your battery charger would have had the balls to lift the battery voltage to 24V. Most battery chargers would go into current limit or simply shut down unless the battery was open circuit. On the other had if the battery was disconnected and you had the car terminals connected to the 24V battery charger then you have probably fried stuff. So here are a few things you could try (assuming you have the tools and competence, I doubt!) Go buy yourself a resetable fuse rated the same value as your EFI fuse and fit it in place of the EFI fuse. Not that familiar with your car wiring diagram... The EFI fuse should just power injectors and maybe ignition too. Unplug all injectors and ignition coils, attempt to start, fuse should not pop. If it does then you will just have to trace the problem. If it doesn't pop, then plug in the injectors one at a time until you blow (pop) the fuse. Repeat for ignition coils until you find what causes the fuse to blow. If its injectors, the ECU drivers are short to gnd. You need to repair the ECU. If you find that plugging in an ignition coil causes the fuse to blow, the problem could be the ECU coil driver or it could be a coil. It would be best for you to seek some help from a friend who has a little electrical knowledge to help. God luck. One last thing... most car electronics should be able to handle up to 15 - 16V. As an alternator can put out voltages in the range of 14.5 - 14.8V
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Would have to agree with @ivan129 step at a time to finding whats causing the short... my thought would be a ground was shorted therefore blowing the fuse... would have my relays checked as well.....