Burning Main Fuses

[MrMarty51]

My 2000 GMT400 K3500. CC SRW Long box.
Things added that might draw some extra amperage.
Air Dog lift pump.
Electro Viscous radiator fan system.
Thats about all that I think thats been installed. No extra stereo amps or some such as that kinds of items.
First time it happened was when I realized that the PO had installed one fifty amp thats the furthest to the back in the under the hood fuse/relay box.
Installed 30 amp units whats called for in the owners manual.
Things going along just fine until I was on my way home from Missoula, round trip.
That was real early morning, had heater fan turned on, probably high as it was early to mid winter. Seemingly for no reason, lights out, engine quit running, dead, everything is dead.
Get out, that one main fuse is burned out. 30 amper unit back into the slot.
All has been well with it until last Saturday.
Wifey has the truck, she has been out for about an hour, driving around after fueling the truck.
I get the call, she is on the trail headed into my sisters place and fuse burns.
She calls, drive to location, another 30 amp fuse.
I tell her to not run the AC.
Truck is parked in front of bay door. I move the truck.
AC button still depressed, blower in off position.
One thing I have heard is the blower motor makes a kind of a quiet whirring noise.
Now I’m wondering that since we are celebrating the 250th year of the founding of Our country, if, it would be okay to liad the parts cannon with one new blower motor and take a shot at the truck with one blower motor ? ? ? ?

 

[MrMarty51]

And as a side note, the heater and AC I think has not been ran since the trip coming home from Missoula.

 

[Twisted Steel Performance]

Check grounds yet?

 

[MrMarty51]

Check grounds yet?

Yup, grounds all bright, shiny and treated with anti corrosion greasy stuff made by truck-Lite or maybe it is Truk-Lite.
I’ll go look.

 

[MrMarty51]

 

[ak diesel driver]

That is simply dielectric grease. Shouldn't be used on the actual connection just used to coat it to prevent water from getting in. In other words make the connection and then apply it on the outside to seal it. Dielectric grease is nonconductive and can interfere with the actual connection

 

[MrMarty51]

That is simply dielectric grease. Shouldn't be used on the actual connection just used to coat it to prevent water from getting in. In other words make the connection and then apply it on the outside to seal it. Dielectric grease is nonconductive and can interfere with the actual connection

Guess I’ll use that no more. Maybe on bulb bases or some such.

 

[MrMarty51]

Main grounds checked and cleaned. They are bright and shiny, including the ground strap to the firewall, RH side.
Blower motor off, engine running.
Fuse temp running 94*f.
Blower motor on high, engine running, blower motor running for about ten minutes.
Fuse temp 165*F.
IDK how accurate my IR temp gun is any more so not sure those are accurate readings.
That main fuse, WO blower motor running is okay to the touch, not cool but near normal skin temp.
After the motor has been running for a while, ten or fifteen minutes, that fuse feels as if it could near burn flesh.
Pulled the jockey box to try and get a motor temp reading but there is this plasticated cover over tye motor.
Going to figure what it takes to get that removed, then, with it still in place, give the motor about a ten to fifteen minute run, pull that covering then get a temp reading.
Allow the motor to cool, even using some compressed air, then do a rerun and see what temp the motor and fuse runs at.
I just dont know any way to run more tests.
I might have to make up some test cables and attempt an amp draw test. Get out the multimeter book and see how to hook it all in.

 

[smokymtn65]

If you look at that cover just right it will just fall off in a lot of pieces at least mine did lol sorry about your troubles man.

 

[Glagulator]

Is this the fuse you are having problems with?

 

[MrMarty51]

Motor winding housing.

Motor bearing end plate.

Fuse in fuse box.

The helper running the controls and barking out orders.


And now.
The motor winding housing at 116 degrees. That does not seem so bad, but IDK how warm they do run with the AC and heat off.
Now the strange part is, I can hold my hand on the motor winding housing for as long as I might want to.
That motor bearing end plate is so hot that within 30 seconds I’d have to pull my hand back, or, it would get so painful from the heat that I’d be forced to retreat or there might be the possibility of getting a bad burn.
Bella was barking that I should hold my hand on there for even longer but her bark is worse than her bite so I retreated.
From now on I’ll stick with cats. At least claw marks gives me something to patch.

 

[MrMarty51]

If you look at that cover just right it will just fall off in a lot of pieces at least mine did lol sorry about your troubles man.

YUP, got it offt in one piece.
Pulled the ECM and the gizmo under it, along with the ECM mounting tray, then I could see and get to the motor wire harness/plug, then some more pulling and tugging and it came right out.

 

[MrMarty51]

That white spot in her eye is one marble eye.

She is definitely a mixed up little character.
Black like a black lab, white blaze on her chest with these bluish/grey polka dots, marble eye and sort of pitty bull jaws.
Because she is so mixed she has emotional issues, cant decide, chew on one of my bones, martins feets, hands, lets play tug of war, here grab this squeaky and pull.
Yup, she is a mess.

 

[MrMarty51]

Advance to about two minutes and fifteen seconds.

 

[jrsavoie]

Check your wires in that area. I'm guessing there's some crusty wires.

I run an extra ground from the fan motor to the dash frame just inches away.

I had more than one GMT400 that the wires and connector up by the ecm were obviously overheated at some point in time