EFI Fuse issue (1 Viewer)

[lezduit]

I just recently bought a 2001 LX470 for college and 2 weeks into driving it, it died while pulling into a parking lot. I found out the EFI fuse had blown and when I replaced it with another it blew again so I searched around and found that it may be the o2 sensors and I unplugged both downstream o2 sensors and replaced the fuse. after doing so the car started just fine. Drove it for the rest of the day with the o2 sensors disconnected. The next day I replaced the o2 sensors with new denso units and drove it to work, on the way, the fuse blew again and I was stranded at a gas station. Disconnected the o2 sensors again but the problem still persisted with the EFI fuse blowing. Pulled the EFI relay and the fuse wouldn't blow, no check engine light but the battery light was on. Got it towed to a shop and they couldn't find an issue however, after looking for a weekend they put in a new fuse and this time it didn't blow. Currently driving it without a problem but I'm worried that it's gonna leave me stranded again. The only thing I did was change the head unit in the past and the previous owner said this never happened to them.

 

[BullElk]

Does the red security near radio stay on when key is in ignition? If so, the thread below is likely your issue. @medtro can fix you up.

My immobilizer fix

I got the famous crank but not start immobilizer problem. I replaced the 20A EFI fuse with a 30A fuse and it started right away. However, it was a temporary fix. I had the same problem again 4 days later. This is what I did to get the engine started. It has been working with no problem for...

forum.ih8mud.com

 

[GremlinMobile]

I think the "fix" in that thread sends constant power to the relay, where the OEM setup would send power then the key is inserted and switched. That concerns a number of people, rightfully so, because of the chance that the battery might be drawn down due to a constant-on electrical connection straight to the battery.

Seems like a much easier and straight forward fix is to take that battery box apart and clean up, wire brush, re-crimp, and/or re-solder the few connections that need it.

 

[BullElk]

I think the "fix" in that thread sends constant power to the relay, where the OEM setup would send power then the key is inserted and switched. That concerns a number of people, rightfully so, because of the chance that the battery might be drawn down due to a constant-on electrical connection straight to the battery.

Seems like a much easier and straight forward fix is to take that battery box apart and clean up, wire brush, re-crimp, and/or re-solder the few connections that need it.

If not mistaken, I don't believe that is correct in that it is constant power. Connecting from battery to "F" relay slot will be constant power for cranking and will continue as constant power if not unplugged. Lots of folks, including me with two of my LXs, keep the bypass plugged in constantly with no battery draw issues. That is the only way to do it. Of course, @medtro could say better.

 

[lezduit]

Does the red security near radio stay on when key is in ignition? If so, the thread below is likely your issue. @medtro can fix you up.

My immobilizer fix

I got the famous crank but not start immobilizer problem. I replaced the 20A EFI fuse with a 30A fuse and it started right away. However, it was a temporary fix. I had the same problem again 4 days later. This is what I did to get the engine started. It has been working with no problem for...

forum.ih8mud.com

Currently the car isn't having the issue but I'll be sure to check for the immobilizer when it does it again. Does anyone happen to know where I can find a wiring diagram for the efi circuit so I can check the wiring? As some have stated that it could be a short to ground.

 

[medtro]

I think the "fix" in that thread sends constant power to the relay, where the OEM setup would send power then the key is inserted and switched. That concerns a number of people, rightfully so, because of the chance that the battery might be drawn down due to a constant-on electrical connection straight to the battery.

This is not true. Zero drained battery reported since 2016.

It would be stupid to use a relay if I wanted to send constant power.

 

[GremlinMobile]

This is not true. Zero drained battery reported since 2016.

It would be stupid to use a relay if I wanted to send constant power.

I guess I don't understand the schematic of how this bypass works. There are several relays and many fuses in this fuse box. I understand you've found a workaround to get the EFI system to work, but aren't the other terminals suspect? Isn't this a bandaid solution, compared to refurbishing the back connections on the box itself? I don't understand why you'd want to route new wiring and fuses and leave the rest of the terminals in that box unaddressed. If this problem happened to one, it could happen to all others.

 

[BullElk]

I guess I don't understand the schematic of how this bypass works. There are several relays and many fuses in this fuse box. I understand you've found a workaround to get the EFI system to work, but aren't the other terminals suspect? Isn't this a bandaid solution, compared to refurbishing the back connections on the box itself? I don't understand why you'd want to route new wiring and fuses and leave the rest of the terminals in that box unaddressed. If this problem happened to one, it could happen to all others.

I believe the root issue is a faulty EFI fuse slot that overheats and melts in the ‘98-02 model fuse boxes.

Some have replaced the $700 fuse box, that still has the unresolved fuse slot issue. Others have taken advantage of a bypass that @medtro has conveniently made available, with zero negative side affects.

I see one solution option to this rare 100 series error the Japanese have made.

 

[GremlinMobile]

Reply

I believe the root issue is a faulty EFI fuse slot that overheats and melts in the ‘98-02 model fuse boxes.

Some have replaced the $700 fuse box, that still has the unresolved fuse slot issue. Others have taken advantage of a bypass that @medtro has conveniently made available, with zero negative side affects.

I see one solution option to this rare 100 series error the Japanese have made.

Well medtro said himself in post 304 "It is possible that new problem has developed underneath A since you installed the kit. It is a growing problem as our vehicles age." which points to that there may be other weak connections in that box. There's a video on youtube about how to take it apart and fix it to avoid the rest of the connections deteriorating as they age.

 

[BullElk]

Reply

Well medtro said himself in post 304 "It is possible that new problem has developed underneath A since you installed the kit. It is a growing problem as our vehicles age." which points to that there may be other weak connections in that box. There's a video on youtube about how to take it apart and fix it to avoid the rest of the connections deteriorating as they age.

Ive never seen or heard of any other fuse slot having this issue. Nor I have I heard f this happening in ‘03 or newer.

You should take your fuse box out, create a permanent repair to the factory fault and show everyone how you do it. Then we can see if a simple bypass is still the best and quickest option to the problem.

 

[kevgentile]

When mine started having the efi circuit problem I decided to open the box and attempt to repair it.
It is a bit of a pain to open and I found the best way was to dremel out the retaining clips. The problem here
is that now it has no way of securing the 2 halves together.

After dissecting the assembly I'm quite surprised that there aren't more issues with other fuse circuits throughout.
Quite a few are loose to the point that I could see some higher resistance occurring and potentially burning out the contacts.
I went through all of the terminals and closed the gaps. I swapped out the EFI fuse terminals with some of the unused ones in
the box, and followed it up with some solder.

When reassembling the unit I first used epoxy to secure the halves but before it had time to set-up I decided to go another
route incase I needed to go back in. I was able to use short 10mm screws and secure the halves through the sides where the
original retaining clips were.

I am satisfied with the results since I was able to retain the original configuration and has remained trouble free.

Just an fyi to those questioning @medtro's solution. It does not supply constant power to the circuit. It operates much the same
way as the original layout. You can build your own and test it. The key has to be on to supply 12 volts to the "jumpers" fused lead.
Key on will energize the circuit and the relay.

 

[GremlinMobile]

When mine started having the efi circuit problem I decided to open the box and attempt to repair it.
It is a bit of a pain to open and I found the best way was to dremel out the retaining clips. The problem here
is that now it has no way of securing the 2 halves together.

After dissecting the assembly I'm quite surprised that there aren't more issues with other fuse circuits throughout.
Quite a few are loose to the point that I could see some higher resistance occurring and potentially burning out the contacts.
I went through all of the terminals and closed the gaps. I swapped out the EFI fuse terminals with some of the unused ones in
the box, and followed it up with some solder.

When reassembling the unit I first used epoxy to secure the halves but before it had time to set-up I decided to go another
route incase I needed to go back in. I was able to use short 10mm screws and secure the halves through the sides where the
original retaining clips were.

I am satisfied with the results since I was able to retain the original configuration and has remained trouble free.

Just an fyi to those questioning @medtro's solution. It does not supply constant power to the circuit. It operates much the same
way as the original layout. You can build your own and test it. The key has to be on to supply 12 volts to the "jumpers" fused lead.
Key on will energize the circuit and the relay.

Interesting. So you took the time to look at the back end of the box to really understand what's going on and why, and you did find other fuse circuits loose. Thanks, that's helpful. I would much rather address this issue preemptively the way you did than spend $140 on $15 worth of wires and a relay for a bandaid.

 

[kevgentile]

Interesting. So you took the time to look at the back end of the box to really understand what's going on and why, and you did find other fuse circuits loose. Thanks, that's helpful. I would much rather address this issue preemptively the way you did than spend $140 on $15 worth of wires and a relay for a bandaid.

Understand that my reasoning to repair the fuse block wasn't due to distrust in @medtro's solution as I built my own relay jumper kit
and it works much the same way as the factory layout, just has the wires exposed and uses a much more affordable efi relay. It's not a bandaid repair, it's just another way to repair/solve an inherent problem. A bandaid is a temporary fix, not a solution.

I am a full-time mechanic and when dealing with a clients vehicle I first make attempts to repair the factory parts, if not, replace. If all else fails, no parts are available, etc, then I will resort to another solution like we have presented to us here, If a customer is ok with it.

In my case I tend to make repairs to my own vehicles much the same way. Maybe out of years of habit, but I will first resort to attempting
to repair the part first. I still have my jumper kit set aside incase I ever need it.

 

[medtro]

I guess I don't understand the schematic of how this bypass works.

That is too soon to call my fix applies constant power and leads to battery draining until you understand what is going on. It is very misleading.

There are several relays and many fuses in this fuse box. I understand you've found a workaround to get the EFI system to work, but aren't the other terminals suspect?

If you want to go this route, everything under the universe is a suspect.

Isn't this a bandaid solution, compared to refurbishing the back connections on the box itself?

No.

I don't understand why you'd want to route new wiring and fuses and leave the rest of the terminals in that box unaddressed.

There was no other problem at the time when I built my kit. What other terminals in the fuse box are left unaddressed?

If this problem happened to one, it could happen to all others.

I think you need a new car. If the EFI circuit in the fuse box goes bad, the rest of the fuse box will go bad. If the fuse box goes bad, the rest of the car will go bad. You are better of with a new car.

 

[medtro]

Reply

Well medtro said himself in post 304 "It is possible that new problem has developed underneath A since you installed the kit. It is a growing problem as our vehicles age." which points to that there may be other weak connections in that box. There's a video on youtube about how to take it apart and fix it to avoid the rest of the connections deteriorating as they age.

"A" or "underneath A" is part of the original EFI circuit. If "A" or "underneath A" goes bad, then you connect the kit straight to the battery. If you have a problem with this approach then this fix is not for you.

 

[medtro]

Interesting. So you took the time to look at the back end of the box to really understand what's going on and why, and you did find other fuse circuits loose. Thanks, that's helpful. I would much rather address this issue preemptively the way you did than spend $140 on $15 worth of wires and a relay for a bandaid.

Build one if you are capable of it. Answer a few questions before the sale, box it with documentation, drive to post office to ship it, answer some more questions after the sale. Figure out the total time and let me know what is that worth. A dealer from southern California bought the kit and told me I am not charging enough for the kit.

 

[BullElk]

…. and then answer a few more questions as if the one asking is your only customer.

 

[ClassyJalopy]

I am also in the camp of @medtro 's fix being a good solution.

Of course the best way to deal with it is to replace the entire fuse box if you can.

 

[medtro]

Does anyone happen to know where I can find a wiring diagram for the efi circuit so I can check the wiring? As some have stated that it could be a short to ground.

LC100 Factory Service Manual

Landcruiser 100 Series Factory Workshop Manual

lc100e.github.io

 

[Mauser]

I am also in the camp of @medtro 's fix being a good solution.

Of course the best way to deal with it is to replace the entire fuse box if you can.

I also think @medtro solution is a good one.

The only bad thing about replacing the fuse box is that the replacement isn't any better than the original. The new one will eventually burn out too. What should have been done in the first place would be to use a bigger fuse. Not a higher amperage fuse, but a physically bigger fuse.