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4L80E 2nd only and blowing fuses

Michaeljp86

Michaeljp86

EVIL GENIUS
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I left for school one cold morning and the trans wouldn't shift, 35mph was about as fast as I could go. Turned around and went home to drive something else. Old rusty but trusty jimmy to the rescue. :thumbsup:

Checked the dipstick, it was good, checked the fuse, it was blown. I replaced it and took it for a long drive and it was shifting good. :skep:

The next day I came across some cellulose insulation machines that were to good of a deal to pass up. I drive 45min one way to pick them up and its driving great. I leave there and its 30mph. :mad2:

I pull off on a side road and the fuse it blown, I change it and when it shifts into 3rd the fuse popped. I changed fuses but still only 2nd gear. I pulled off at a public park and pulled the battery cables off to clear the codes and checked the fuse but it was good. I drove off and it was shifting good, I got out on the main road and 2nd gear only.:cuss:

30mph the whole way home. I stopped at my house I just bought and drop off the machines, pull the cables and put in a new fuse. I go to drive home and pop, 2nd gear only.

The next day I got up under there and around the bell housing between the firewall the outer plastic on the wire loom was brittle and falling apart. It looked like a wire was rubbing. I cut a piece of hose and put it around the wires and so far so good.

I thought Id post this so if anyone has a similar problem they know where to look first.
 
If it has rubbed through, then you need to replace the harness or else you will have more trouble in the near future. I've encountered this with farm trucks taht get mud and such packed up on teh harness and it rots the plastic insulation off. Only long term fix is to replace the wiring in the harness.
 
Three causes for same issue on my truck. 1. outside harness. 2. inside harness (change solenoids while you're there). 3. Brake switch.
 
THEFERMANATOR said:
If it has rubbed through, then you need to replace the harness or else you will have more trouble in the near future. I've encountered this with farm trucks taht get mud and such packed up on teh harness and it rots the plastic insulation off. Only long term fix is to replace the wiring in the harness.
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Ive seen it happen too on marine engines, water gets into the tine space between the strands of copper wire and corrosion starts.
 
oldblacksmoker said:
Three causes for same issue on my truck. 1. outside harness. 2. inside harness (change solenoids while you're there). 3. Brake switch.
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Ive changed the solenoids when I got the truck, one of them wasn't working too good and eventually gave up the ghost. Since it popped the fuse when it went to shift I figured it had something to do with the solenoid or the wire going to that solenoid.
 
ya i have a thread going up 6.5 litre heading call computer comuitication i haved it scan and i cant get any code. its like the computer isnt in the truck. the truck will start off good the after driving 30 seconds it down shift to 2nd gear.
I through most of the grounds under the hood, the ones i can find.
 
k_nine said:
ya i have a thread going up 6.5 litre heading call computer comuitication i haved it scan and i cant get any code. its like the computer isnt in the truck. the truck will start off good the after driving 30 seconds it down shift to 2nd gear.
I through most of the grounds under the hood, the ones i can find.
Click to expand...

I had a similar issue, if I shut the key off and turned it back on it would correct the problem normaly until the truck cooled down. I'm not sure if I still have the problem or not. I dont drive the truck in the winter.
 
ya it sucks cause i love the truck and i hater seeing it sit there and i need it, I tow a car trailer. i just bought a filter for it just have to change it. Well im there i can take a closer look at the wires there too
 
They make a mechanical valve body for these transmission. If mine ever bites the dust Id like to go that route so these electrical problems wont hold me up.
 
k_nine said:
i took my truck for a drive yesterday and shifted it manually i can get to third gear. no overdrive
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Try changing the temp sensors, Im pretty sure if the computer thinks its super cold it wont let it into 4th to protect the transmission.
 
k_nine said:
yup so far so far. changed the coolant sensor got my over drive back.

thanks for letting me hijack your thread
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I bet you feel a lot better. I felt so sick when I was having the trans problems.

Ive been having some OD issues myself. Ill try changing the sensor. I never even thought of that being the problem.
 
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