8970 blowing fuse

Blue Empire

New User
1994 8970 4,000 hours blowing main fuse to dash and all power, 40 amp fuse under console. any hints on where to look first. just purchased tractor ran 10 hours started tonight for about 10 seconds and now dead replace fuse dash comes on for second a blows fuse. thanks for any advice.
 


There are so many avenues to take!

I got an 8670. That thing is an electrical monstrosity. So, you have to be a lot more specific, and explain everything.

Which fuse, exactly, are you blowing? are we talking about the fuses in the pillar fuse panel? Please describe what fuse, and it's exact location.

After I have that info, I can begin o take you down a diagnosis route. Just saying, a fuse is blown is about useless. Start at the start, then we can move along.

Bern will chime in. He is great!
 

Generally speaking, to blow a 40 amp fuse takes a short in a big wire. I would expect that it is a major wire that has rubbed the insulation off from chafing. It should be obvious once you lay your eyes on it.
 
Late night, main power center, fuse #2 main fuse. this is the fuse bank under the console right side near the floor. It should be a 50 amp which I also tried and blew as well.
 

I don't know how much help I'll be here, but here goes. MFP #2 does not power many things without going through other smaller fuses. One thing it does power is the Auxiliary Power Relay in the MDP (Main Distribution Panel on the right cab pillar). It's relay #12. This would make sense, since your ECM is going out.

Here's the steps, I'd follow:

1. With MFP 2 and MDP Relay 12 removed, check for continuity to ground on the non powered side of the fuse receptacle. If it's there you have a short in either circuit CM15B or CM178. The are Cab Main Harness circuits and should run from the MFP directly up to the MDP. Both are red wires. The former is 8 gauge, the latter 10.

2. If no short here, reinstall MDP Relay 12 and try again.

3. If you get no short on step 1 and short on 2, rob an identical relay from a non-essential spot in the MDP. Try it again.

If you get this far and still don't have your answer, post back and we'll try some more wire chasing.
 

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