ascott.1

I think I have solved this riddle, so I wanted to post for anyone else out there having the same issue. 2005 Toyota 4Runner SR5 V6 4WD 126k

I drove about 4 highway miles plus about one city and stopped and shut off the motor. Five minutes later I tried to start it again and got the lights and bells like normal, but when I turned the key to start, nothing happened. My battery is only about a year old, so I was pretty sure that wasn't the issue, but I tried jump starting anyway with zero results. After doing some research, I decided to focus on the starter so I removed it. It bench tested fine, but after the PITA of removing it, I decided maybe there was a hidden short and I would just replace it anyway so I didn't have to go back and redo that ˟˟˟˟˟ job in a year or whatever. After replacing, it started right up and I assumed the problem was fixed. NOPE! It happened again the following day after a short trip of about four city miles. This time I found some info on the forums about the starter relay, so I bench tested it and it failed one of the checks, so I replaced it. Once again, it started right up and I assumed the problem was fixed. NOPE AGAIN! The next day, another four city mile trip and the same thing happened. That's when I found this post: https://www.yotatech.com/forums/f117...nd-all-233313/ and next paged to the end to see what he figured out. My issue was the same and my conclusions are:
a) The factory screwed up and punched the EFI fuse in there too roughly and bent the leg from the beginning.
b) Poor contact is the cause of the heat scoring. There doesn't appear to be any heat damage in the fuse box.
c) Constant heating and cooling eventually weakened the plastic enough that it wasn’t making consistent enough contact to run the engine anymore.

If you look at the fuse block the contact on the left is only 1-2 mm wide as opposed to the contact on the right that is the width of the fuse leg. I know the bent leg was on the side with the narrow contacts, which means the leg of the fuse was only laying against the side of those contacts. You will also notice that the fuse "failed" without breaking the filament, so if you test it from the top with a tester, it won't show bad.

Hopefully this helps someone before they put in a bunch of time and money to discover the problem is simple. Let me know if you have any questions.

RAD4Runner

Glad you figured it out and thanks for sharing. Like I always emphasize, Toyota parts are bullet-proof. Problems arise from bad connection, poor assembly, poor maintenance. In your case both the former two applied.


There must have been a problem with the factory or the design of that fuse holder if it happened to more than one 4Runner.

exactly.

Correct, if you simply do a voltage check referenced to ground.
That's why it's best to also do a "voltage drop" measurement across any suspect part.
To do this:
You turn on the load so you have current "trying' to flow through that fuse,
Measure voltage "drop" from one side of the fuse to the other, AND
Measure voltage from one terminal of that fuse holder to the other terminal (behind/under the fuse block).
If you get a reading greater than zero, that indicates a bad fuse/ fuse holder / connection between fuse holder and fuse.

Matt Huber

Same problem here. Intermittent no start. (No crank, no click, nothing.) Found this thread and pulled the EFI fuse. Found what you see in the photo below. Replace the fuse, seems to work well now. Time will tell. Anyhow, thanks for the tip!

STC

Same thing happened to my '06. Same fuse, and looked like Matt's photo. I first just replaced the fuse, but later had is overheat and blow again (within a few months). Looked to be even more burnt. On inspecting the fuse box connectors, they were damaged and corroded. I ended up going in with an fine emery board to fix the surface then applied a coating of DeOxit Gold. That was 4+ years back and the problem has not returned.

I think portions of the electrical are undersized (ask me about the issues related to the blower motor and blower controls burning up). There are a number of connectors that get very hot after being in use after a long drive. After my series oe electrical meltdowns, I went through and cleaned and treated about a dozen connectors in the truck with DeOxit products. I can't say for sure that did anything, but I haven't had any electrical connector issues since taking those steps.