Crank fuse - what cause to blow?

[Bob H]

My 99 Astro with only 75k miles has intermittent problem of blowing the 10 amp "crank" fuse (labeled as #8 fuse under dash, drivers side).
Of course when this fuse blows, the starter does not crank when you turn the key.

This is the 3rd time in 2 years that the fuse has blown, and it has a bit of smokey residue inside like it didn't slowly melt.

Is there a way to test for wire shorting to ground? Would I isolate that wire by pulling the starter relay under the hood?
I have an earlier thread viewtopic.php?f=62&t=9289 where my van wouldn't crank, and mysteriously "fixed itself" with no repairs made.

Actually that has happened twice now. And yesterday, the van left me stranded somewhere (wouldn't crank) after no problems for a year.
I got it to crank by jumping the big hot lead on the solenoid (top post, wire coming from the battery) down to the small post in the middle) where the crank wire goes from ignition). That was before i discovered the blown fuse, so I don't know if my action blew the fuse or not.

So I don't know if I have an intermittent / bad neutral switch on the tranny, or ignition switch, or starter relay, or partially chewed wire shorting to ground somewhere between these components. It's nothing obvious or visible.

What would be causing this fuse to blow? One of the times this fuse blew in 2012 it was changed out and still wouldn't crank - which makes me wonder if I am blowing it by trying to jump the solenoid for testing... sorry to be vague here.

Right now, with new fuse in place, it cranks and runs fine. So there is an intermittent problem and I don't trust the vehicle.

[Drummernaut]

First thing I will ask is when you are/were having the cranking issue, did you ever try to crank when in neutral?

Fuse #8 is between the start switch of the key and the shift position switch which is on or in the transmission. From there it goes to the starter relay in the fuse center under the hood.

It is possible that the transmission switch is out of position causing poor connection when trying to start or your starter relay is having some intermittent fits.

Next time when you can't start but have a new fuse, try starting around the neutral area to see if it will start. If it does you may have to adjust the transmission switch position.

If not that then check the starter relay. Look for burn or corrosion.

Used to happen allot on my old dodge van.

[Drummernaut]

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