AUYota

My EFI fuse keeps blowing. When it goes, the Runner dies. I guess there is a bad ground. Is this something I can trouble shoot myself? Where would I look?

Saint_Berzerker

Yeah...had the same thing and it was my oxygen sensor wires melting on the exhaust pipe and grounding out.

The oxygen sensor is by the Catalytic converter. See if the wires coming from the oxy sensor are anywhere around the exhaust. If they are, you'll have to fix it and tape them up and get some tie wraps and move them outta the way.

It happened to me while I was driving and going out of town. My truck just died. I had no idea why. Luckily I had my laptop with my air card in it and was able to do a Google search and man, there were thousands of hits and everything pointed me right there....and I got it fixed. I never would've found it without my computer...lol.

AUYota

As I figured nothing is ever that simple with my rig. I looked at the one O2 sensor I have and the wire harness goes straight up, never touching the pipe. However, it was on top of the metal (heat shield?) above the tail pipe in that area. At that part of the wire was a heavy piece of insulation around the wire that appeared to have gone through the ringer. Tomorrow I'm going to slice into it and the wire covering as far as I can to see if the wires are better. I want to think I jiggled the wires enough that I fixed it, because it's not blowing fuses anymore. However, I'm sure I just jiggled them enough so that it's just not doing it right now.

Any other suggestions?

Also I found this suggestion on a google search but would like for someone to further explain it to me
"If this is a V-6 make sure the EFI ground is attched properly to the right cylinder head at the back of the valve cover"
Where is this location more specificaly??

DirtCheap

I, added a few extra grounds from the engine to the body. You can't have too many grounds! Look on the back of the passenger head and you'll see the ground cable. Also consider removing the grounds and clean the contact area and possibly add a few new ground wires.

Good Luck

AUYota

I was driving it around the parking lot to see if it the Runner could survive a trip to Auto Zone. No such luck. However this time, putting a new fuse in doens't help; it just blows it when you crank the Runner. I got some jumper cables and attached one to that (hook?) attachment on the engine next to the ECU and the other to the frame underneath. That work for a minute, got me back to my side of the apartment complex, but eventually died. Any more suggestions???

Saint_Berzerker

Well, man....it's got to be a wire getting grounded out somewhere...nothing else really. Get the electrical schematic and just start tracing everything.

I don't think you'd have a "bad part" anywhere...just a darn wire somewhere that either melted to a ground point or something.

AUYota

***

Any ideas???

4runnermt

Did you check all the ground wires? They can look clean and not ground out properly. I would remove all the ground wires and sand each mating surface to make sure you have a clean contact.

AUYota

Where are ALL of the ground wires?

midiwall

Ummm... it may just be a case of semantics, but...

Having a bad ground itself will not blow a fuse. Fuses blow because there is too much current being drawn through them. If a ground was intermittent, then you're talking about either NO current or SOME current being drawn through the wire.

The EFI fuse is a 15 amp part - that's a LOT, considering that it's supporting the ECU which draws about 100ma in rest and about 3 amps when the injectors are firing.

You shouldn't be looking for a bad ground... It's obvious that you have a good ground since current is flowing to the ECU (and blowing a fuse) when you crank the engine. What you need to look for is the _power_ wire to the ECU shorting out TO ground. Also look at things that the ECU drives, like the injectors. It's possible that a shorted lead to an injector could draw too much current through the ECU and blow a fuse.

Saint's also touched on the O2 sensor, which seems weird until you realize that there's a heater in there which... ...is driven by the ECU.

AUYota

Well I got the Runner over to a good Auto electritian I know, and he found some bad wires that got some water damage which he replaced.
I got about a mile down the road and she died on me again. Again blowing the EFI fuse. It blew a 20amp fuse too (the EFI calls only for a 15). Oh well he towed it back and will look at it next week.
Oh well...

DirtCheap

Do not use a higher capacity fuse, you're just asking for more problems.

ovrrdrive

I know its already been said, but you are not looking for a bad ground. You are looking fo a wire that has 12V+ in it that is pinched, cracked, or otherwise has bad insulation and it making contact with the frame or another ground.

It could be inside a wiring harness too... It may not be obvious.

If you have screwed anything to the floor inside the truck that would be a good place to start looking.

Also, if you have had any major work done to the engine they could have damaged a wire there too.

Start seperating wires and taping them even if they look ok. Maybe you could put a good fuse in and turn the key on (without starting the truck) and go out and wiggle wires uner the hood until you hear or see a pop.

AUYota

I'm sure it's not a bad ground but a bad wire like you say. There were some obvious wires and they were replaced, but it did it again. What is so annoying is that the bad wire or whatever will "fix itself" for a short time then blow the EFI fuse.

ovrrdrive

Seen this thread at Pirate?

http://www.pirate4x4.com/forum/showthread.php?t=488415

midiwall

Umm, I think it's his thread...

"Auburn, LA" versus "Auburn, CA".
The make/model/year of the rig is the same.
The symptoms are identical.
The work thus far is identical (down to using a 25amp fuse).

AUYota

Nope, not my thread, but it has gotten me thinking about that wire to the O2 sensor again. I think I'm going to tell my mechanic friend to check it out. Can that wire actually melt in the insullation? wow...

oh yeah FYI,
I live in Auburn AL. he's in Auburn CA. that other guy has a Tacoma I have a Runner, he used a 25amp fuse as a permenant fix, I used a 20amp just to get me to Auto Zone (I didn't make it) He used a 25 amp fuse for days on end (dumb) He's got other problems with a fan busting the battery or something...
Althought simmilar that isn't my post....

ovrrdrive

I was thinking it was different...

At first I thought it was you as well, but like you said there were several differences.

And even though his sig says tacoma in it, the post is about a 3.0.

Amazingly similar though no?

AUYota

Yeah how many towns are named Auburn???

AUYota

Ok it's fixed !!!!

:bigclap: