More evidence that fuses are wear items (1 Viewer)

Eicca

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When you buy an LC and baseline everything, do you change the fuses as well? I certainly didn't when I bought my 1UZ-powered GS400...

I've owned it for four years now, and it's always had a sloppy 1-2 gear change. I chalked it up to abuse from the bozos that owned it before me.

Last year it started running rich, and at first I thought it was a dirty air filter. Seemed fine after replacing that. But the problem kept coming back, and I noticed that the O2 sensors were all flatlining in their voltage readings, simultaneously, but randomly. Then over the last month it started running worse and worse. Noticeable power inconsistency, rough idle, and even backfiring. Read about it here.

That 1-2 gear change also was getting more slippery.

Last week while limping it back home, it's running like utter garbage, no power, backfiring, etc, and I noticed that all the O2 sensors would flatline and the long-term fuel trim would jump to -35% when I would give it throttle. Almost like the sensors weren't getting the power they needed. The only other time I've experienced something like that was when my alternator crapped the bed and I was running on a drained battery. Give it gas, and it falls on its face.

Checked all the wires, checked all the grounds, and decided to check the EFI fuse as the last easily-accessible variable in power delivery to the ECU. Said fuse tested fine with a multimeter, but it was pretty discolored, so I replaced it anyway. Couldn't hurt.

Now, I am waiting for one month to pass problem-free before I declare total victory...

But the car has never run better. The fuel trims are right back to normal (+/- 5% at idle and nearly dead on 0 at RPM) and it's got loads of smooth power. Not only that, the transmission responds noticeably quicker, and for the first time EVER, I can feel shift shock between first and second, even at WOT. That has never happened in the entire time I've owned this car.

Anecdotal? You tell me. I've reset this ECU dozens of times and never felt a lick of difference in the transmission. But there is a true principle that low power can make computers do all kinds of whacky things. All I changed was the EFI fuse.

TL;DR - If you have an old vehicle, replace the fuses and I bet it feels healthier afterward.
 
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Nah, its not your fuse. They don't usually go out unless its shorted.

All of your signs point to you needing a new fuse box. They are about $650 and are a common problem. They will arc the EFI fuse, and you caught yours before it went out completely with a no start but yes crank condition.

Go replace your fuse box or get the EFI fuse fix from one of the members here.
 

Eicca

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Well there's no other explanation, I've removed and reinstalled the old EFI fuse numerous times, cleaned its contacts... The transmission felt instantly better after putting in the new fuse.
 

Eicca

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That 1UZ-FE is a fine looking engine. Does your GS400 have an efi fuse or an efi relay like the 100 series?

Definitely a fuse (I replaced it) and I'm pretty sure there's an EFI relay in there somewhere... The wiring architecture on the GS and LC is quite similar, according to the EWD.

EDIT: Yes it does, right beside the fuse. Maybe I should replace that too just to be safe.
 
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When you change a burnt bulb in your laundry room the new one is always brighter than the old one, so why not? The fuse is the weakest link in an electric system, it’s a piece of copper that can corrode inside a cheap plastic cover, and it’s cheaper than a transmission replacement, so not a bad idea to try that one first..
Baselining is getting more and more expensive...How much is a car lease payment again?
 

Eicca

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All of your signs point to you needing a new fuse box. They are about $650 and are a common problem. They will arc the EFI fuse, and you caught yours before it went out completely with a no start but yes crank condition.

Land Cruiser fuse boxes are $650?! OEM box for the GS400 is $175 MSRP. $85 if I order it as a Toyota Aristo part.
 
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likely in the salvage yard
From what iv'e read here on the 2UZ-FE The EFI relay loses connection inside of the fuse box sometimes causing no-start conditions. Maybe the advice above abt. getting "EFI fuse fix" ( My immobilizer fix ) will be helpful for u to research regarding your issue. The efi fuse may be a lucky early warning of pending or intermittent failure inside your fuse box. Good Luck!
 

Eicca

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Joined
Apr 26, 2009
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Utah
From what iv'e read here on the 2UZ-FE The EFI relay loses connection inside of the fuse box sometimes causing no-start conditions. Maybe the advice above abt. getting "EFI fuse fix" ( My immobilizer fix ) will be helpful for u to research regarding your issue. The efi fuse may be a lucky early warning of pending or intermittent failure inside your fuse box. Good Luck!

I'd much rather replace a fuse box preventatively than an ECU as a guess!
 

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