Any loose connection is a bad thing. All current supplied by the battery has to return to the negative battery terminal (ground).
You wrote, "The lead going to the engine has +12v at that connection point." What are you referring to?
Died while driving.
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You wrote, "The lead going to the engine has +12v at that connection point." What are you referring to?
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- #82
See the two wires coming from the negative terminal? The thinner wire connects to a bolt on the chassis. The larger one leads under the air filter box to a metal frame near the engine block. I was checking the ground from the terminal to both connection points (the chassis and the metal frame near the engine block. I got +12 on both spots. I will upload a picture of what I mean later (at work the next two days). So should I just go ahead and buy a new battery as well as new terminals? Thanks.
OK, I'm pretty sure you didn't measure +12 on ground. There would be a fantastic light show if that were the case.
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- #84
update: installed new battery terminals, put in new fusible link (first one burnt up), drove around the neighborhood. All good. No issues. Hopefully, the bad terminals were the issue. Crossing my fingers...
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- #85
Update #2: was driving down the highway (about 13 mile in), about 70 mph, electric cut off again like before. Pulled over, looked under the hood. Fusible link burnt up AGAIN in the same place (touching the positive terminal). Placed new terminals one day prior, definitly a short somewhere... where to look is my next question. I may jsut end up taking this truck in to a professional. Im not an electrician and definitely do not want to make anything worse. I can most likely fix the wiring under the fuse box, but If it runs anywhere else, I may need someone else to have a look at it. Thoughts?
And I will ask again...
Which of the 3 fusible links opened up?
Which of the 3 fusible links opened up?
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- #87
Ill post a picture tomorrow (Merry Christmas). This way you can see what I see. I believe its the AM2..
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- #88
I saw this post in the "Another fusible link / electrical gremlin post..." from @george_tlc
Answering some of your questions.
The fusible links are on the POSITIVE post of the battery. There entire body/chassis etc is ground.
Any positive wiring short to body/chassis will blow a fuse or fusible link, all depends on the particular positive wire (i.e. whether there is a fuse protecting that wire or only the fusible link).
A 5A fuse is way too little to replace a fusible link for testing. Most of the links are in the 50 to 100A range. Other than the starter motor, your entire battery current flows through those 3 fusible links to the rest of the electrical system.
As Tools mentions, a common shorting area is the harness (with the injector/tps/iac etc wires) by the EGR valve. The clip that keeps the harness away from the EGR (HOT) valve breaks and the harness can rub (melt) and short against the EGR valve (ground). As the motor moves on the engine mounts as you drive/accelerate etc the short can intermittently occur.
Another possible spot for harness shorts is behind the glove box where the harness runs to the ECU and can be too close and rub on the sharp metal that is goes by. This is a problem on some 80's while on others the factory routed the harness safely away from the sharp edge.
cheers,
Another fusible link / electrical gremlin post...
could this be a problem I am running into @jonheld
Answering some of your questions.
The fusible links are on the POSITIVE post of the battery. There entire body/chassis etc is ground.
Any positive wiring short to body/chassis will blow a fuse or fusible link, all depends on the particular positive wire (i.e. whether there is a fuse protecting that wire or only the fusible link).
A 5A fuse is way too little to replace a fusible link for testing. Most of the links are in the 50 to 100A range. Other than the starter motor, your entire battery current flows through those 3 fusible links to the rest of the electrical system.
As Tools mentions, a common shorting area is the harness (with the injector/tps/iac etc wires) by the EGR valve. The clip that keeps the harness away from the EGR (HOT) valve breaks and the harness can rub (melt) and short against the EGR valve (ground). As the motor moves on the engine mounts as you drive/accelerate etc the short can intermittently occur.
Another possible spot for harness shorts is behind the glove box where the harness runs to the ECU and can be too close and rub on the sharp metal that is goes by. This is a problem on some 80's while on others the factory routed the harness safely away from the sharp edge.
cheers,
Another fusible link / electrical gremlin post...
could this be a problem I am running into @jonheld
I dont need a picture. Each link feeds separate sub-systems. In order to help you trace the short, I need to know which of the 3 links failed to help narrow it down to 1 of the 3 sub-systems.
You already know how to test each link in system because we've gone over it twice now.
George is referring to the common trouble spots on the 1FZ-FE engine (FZJ80 1993-1997).
However, the ECU harness on the FJ80 (1991-1992) has been known to chafe where the wires pass through the firewall. Even though the ECU lives in the same location as the later trucks, the wire routing is slightly different and doesn't come in contact with the metal frame of the dash support on the bottom of the glovebox area.
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- #91
This is the link that keeps opening up. The one with the grey connector. I believe this is AM-2. I have burned through three of these now. Same link.
For the 1FZFE, the fusible links go on the Positive terminal however it appears you are hooking them up on the negative terminal. Am I missing something?
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- #93
Their defiantly placed in the positive terminal.
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- #94
Are you missing a wire on the fusible link? Should be 3.
He has the three wire fusible link but only shows the damaged wires.
If you're blowing up AM2, then look for a short along the injector harness or igniter/coil harness.
Since it doesn't blow right away and only when you're driving the truck, you're looking for a harness that moves in relation to the engine.
IOW, as the engine moves on its mounts, some wire is making contact with a ground point (any metal on the engine or in the engine bay). This wire has had its insulation rubbed off over time.
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- #98
Any diagram out there that shows where these two harnesses are located? Or pictures? I may have an idea, I will take some pictures and post later. Thanks again!
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- #99
@jonheld
So, here are a few pictures of my wire harness coming of the positive battery cable. The AVS-3 wire seems to be the one that is causing the fusible link (AM-2) to blow. I traced this all the way through the engine compartment and have not seen ANY damage. A few wires Amy be exposed but nothing melted or warped. Am I missing something here? Also I noticed while looking through the engine that this piece has broken off. I believe it relates to the temperature gauge. This broken piece is located behind the fan belt where the radiator hose enters the top of the engine. could this be causing my engine to overheat, indirectly causing this fuse to blow? Also engine coolant tank is completely dry. There is some in the radiator.
So, here are a few pictures of my wire harness coming of the positive battery cable. The AVS-3 wire seems to be the one that is causing the fusible link (AM-2) to blow. I traced this all the way through the engine compartment and have not seen ANY damage. A few wires Amy be exposed but nothing melted or warped. Am I missing something here? Also I noticed while looking through the engine that this piece has broken off. I believe it relates to the temperature gauge. This broken piece is located behind the fan belt where the radiator hose enters the top of the engine. could this be causing my engine to overheat, indirectly causing this fuse to blow? Also engine coolant tank is completely dry. There is some in the radiator.
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- #100
wire harness...