What can blow the 400amp on the battery positive distribution buss?

[Sloan17]

I’ve blown the 400amp fuse that is part of the distribution buss on the battery. Starter has been replaced.

[kickass audio]

i've seen where a shorted out starter hot wire blows it, the power wire feeding the starter rubbing on a heat shield or anything metallic can do it too. Also something with a bad jump start potentially can do it.

[richard wysong]

Welcome to the Forum! It would have to be a dead short pretty much. I agree with K A, check the battery cable to the starter

[Sloan17]

I found the problem. The water pump is seized. High starting amps blew the fuse. Thanks for the reply’s. 

[richard wysong]

Wow, never seen a seized water pump! What vehicle are we working on?

[kickass audio]

48 minutes ago, Sloan17 said:

I found the problem. The water pump is seized. High starting amps blew the fuse. Thanks for the reply’s. 

dang I would never have guessed that. How did you not burn up the belt? My dad's 97 Tahoe had the A/C compressor seize up on him from constantly refilling due to a small leak and not putting any PAG oil in the system. When his compressor was stuck the drive belt melted and caught fire under the hood.

[richard wysong]

i agree Kick ,somethings not making sense, water pumps get looser, not tighter, the belt should have burned or broke, there's more to it I'm sure. I guess if it just popped the fuse he's lucky

[Sloan17]

I’m not exactly sure when the pump completely seized. I stopped for gas on the way home from the dealership and the truck wouldn’t start. After trying to jump start it, I called AAA and they towed it home. The next morning I pulled the starter out of the block with the wiring attached. The bendix worked, but motor didn’t. I decided the wrecker driver was right and bought a replacement at $ 359.00. Same result. Went online and researched what else it could be and found out about the buss on the battery being fused. Volt meter told which fuse was blown. A new buss was a dealer item, so I jumped it to ( with jumper cables)troubleshoot further. First time it started fine and ran for ten minutes at idle then died. Restarted with a eye to eye battery cable and smoke came from the front of the engine. Started troubleshooting the next morning ( thought I had burned something electrical with the jumper wire) and found nothing wrong electrical. Restarted the truck and could see (in the daylight) that the belt was slipping on the crank pulley. Found the water pump pulley too hot to touch. Pulled the belt off and found the pump seized. Engine never ran hot or leaked any water. I’m 63 years old and have never seen this type of failure before.

[richard wysong]

Yes sir, VERY unusual, What vehicle/engine? Glad you figured it out!

[Sloan17]

5.3 L gas 

[Sloan17]

It’s a 2020 gmc sierra with a 5.3L gas engine. It only has 34000 miles on it. Far too soon for a water pump failure.

[richard wysong]

Let us know when you get the pump off if it was just the bearing or some other failure. Sounds like something might have got caught in the impeller

[Sloan17]

I try to get something from the dealership. Found out this morning that I still have a power train warranty that covers this.