2019 Ram 1500 N6 300 amp Fuse Blow Up

[racterman]

Hi guys! I'm having a lot electrical issues with my 2019 Big horn. The first thing that happened was a death battery that i replaced right away. My truck was running like a charm for a few month until it won't start at all just clicking. At this stage i did a battery test, it was under 12 v but in good shape so i started troubleshooting the issue and i found a couple of fuses out into the interior fuse box and into the high current fuse array the N6 300 amp fuse blow up too. i just ordered the high current fuse array in mopar store and replaced the rest of fuses but before to put the truck running i would like to know what can cause this kind of problem because may be there is other component compromised. there is almost no information about 5th gen of Ram and its hard to know how their systems work. But i found that the N6 fuse is related with the Power Package Unit (PPU) but my model isn't E-Torque so right now I'm lost. Right now the battery light is on and it won't charge the battery (i forgot mention that i had replaced the alternator as well) If some of you have some similar experience or had o some information about this issue pls help!

 

[6of36]

Hi guys! I'm having a lot electrical issues with my 2019 Big horn. The first thing that happened was a death battery that i replaced right away. My truck was running like a charm for a few month until it won't start at all just clicking. At this stage i did a battery test, it was under 12 v but in good shape so i started troubleshooting the issue and i found a couple of fuses out into the interior fuse box and into the high current fuse array the N6 300 amp fuse blow up too. i just ordered the high current fuse array in mopar store and replaced the rest of fuses but before to put the truck running i would like to know what can cause this kind of problem because may be there is other component compromised. there is almost no information about 5th gen of Ram and its hard to know how their systems work. But i found that the N6 fuse is related with the Power Package Unit (PPU) but my model isn't E-Torque so right now I'm lost. Right now the battery light is on and it won't charge the battery (i forgot mention that i had replaced the alternator as well) If some of you have some similar experience or had o some information about this issue pls help!

I can't find anything different about that fuse, but to blow a 300A fuse, you have a dead short. All I can say, is track the wire that goes on that terminal. It has to be thick and easy to trace. There should be a big burnt spot where it shorted.

 

[racterman]

I can't find anything different about that fuse, but to blow a 300A fuse, you have a dead short. All I can say, is track the wire that goes on that terminal. It has to be thick and easy to trace. There should be a big burnt spot where it shorted.

that make senses, i will do what you suggested and i will provide an update. Thanks fro your answer.

 

[kapinallinen2]

ALLDataDIY is your fried.
Do It Yourself Automotive Repair Information | ALLDATA DIY
The 300 amp fuse is for the alternator in a non e-torque.

 

[racterman]

Yeap! I did what you suggest and you right, it’s the alternator fuse. I’m still waiting for the fuse array arrive, it should be at home by tomorrow so I will replace the bad one and see what happens later. I don’t know how common is this issue I wonder what could cause it. In the process of getting fix this issue I had replaced the alternator by a new one so with all that I guess this will be the final fix. I will keep you updated.

I appreciate your help, so far you has been the only one that answered.

 

[ben b]

Caution: I'm not an auto mechanic, so feel free to ignore my comment.....

It takes a 0.04 ohm short (or less) to cause 12V/300A short. This is an extremely low resistance. I've seen this type of event in a non-automotive application when a small wire or other piece of metal gets caught between the +12V and ground. In this case, the offending wire typically vaporizes, so when you replace the fuse and re-energize the circuit, things return to normal.

But... it seems to me that another very likely place for the fault would be inside the alternator itself. I wouldn't be surprised if you end up replacing it. It would be handy if you had an easy way to verify that you don't have a fault internal to the alternator without dumping another 300A into it. Not sure how you might do that.

 

[racterman]

Caution: I'm not an auto mechanic, so feel free to ignore my comment.....

It takes a 0.04 ohm short (or less) to cause 12V/300A short. This is an extremely low resistance. I've seen this type of event in a non-automotive application when a small wire or other piece of metal gets caught between the +12V and ground. In this case, the offending wire typically vaporizes, so when you replace the fuse and re-energize the circuit, things return to normal.

But... it seems to me that another very likely place for the fault would be inside the alternator itself. I wouldn't be surprised if you end up replacing it. It would be handy if you had an easy way to verify that you don't have a fault internal to the alternator without dumping another 300A into it. Not sure how you might do that.

What you described make sense in the electrical environment dispirited of the application , especially in a 300 amp circuit. When I noticed that the battery wasn’t charged and it was under 12v I did some basic troubleshooting based on people with some automotive electrical knowledge but after no found the core problem I’d replaced the alternator by instinct due the battery is in good condition based on battery test. So I’m wandering that once get the fuse array and replace the bad one all be back to normal but that just my guessing and my hope . I really appreciate your help. I will keep you updated.

 

[kapinallinen2]

You have the high current fuse assembly all taken apart.
Why not measure the resistance from the alternator cable to a known good ground, should read open or in the Mega ohms.
Two things that could have blown that fuse (short of someone monkeying around, not knowing what they were doing)
are a chafed cable or a shorted rectifier assembly, that is internal to the alternator.
You already replaced the alternator so that could be ruled out, ohm out the cable and if OK, you should be good to go.

Want to play it safe, put a temporary 50 or 70 amp fuse in series with the 300 amp connection, reconnect battery but do not start the truck.
If there is a problem, you will blow the sacrificial fuse but not the 300 amp one.

 

[racterman]

You have the high current fuse assembly all taken apart.
Why not measure the resistance from the alternator cable to a known good ground, should read open or in the Mega ohms.
Two things that could have blown that fuse (short of someone monkeying around, not knowing what they were doing)
are a chafed cable or a shorted rectifier assembly, that is internal to the alternator.
You already replaced the alternator so that could be ruled out, ohm out the cable and if OK, you should be good to go.

Want to play it safe, put a temporary 50 or 70 amp fuse in series with the 300 amp connection, reconnect battery but do not start the truck.
If there is a problem, you will blow the sacrificial fuse but not the 300 amp one.

View attachment 170147

You have a good point, I was thinking about to put a temporary low amp fuse before install the high current fuse array to see what happens . I’ll keep you updated. I really appreciate your help

 

[racterman]

Ok guys finally I installed the fuse and it’s charging correctly but others problems pops at cluster panel. Problems related with the stability control and the 4x4 is unavailable and rear camera not working even the icon from the Uconnect disappeared . But the 4WD it’s working apparently . Any thoughts about this new issue in my truck?

 

[Scap]

Ok guys finally I installed the fuse and it’s charging correctly but others problems pops at cluster panel. Problems related with the stability control and the 4x4 is unavailable and rear camera not working even the icon from the Uconnect disappeared . But the 4WD it’s working apparently . Any thoughts about this new issue in my truck?

Give the computer time to wake up. Those issues should clear on their own.

 

[6of36]

Ok guys finally I installed the fuse and it’s charging correctly but others problems pops at cluster panel. Problems related with the stability control and the 4x4 is unavailable and rear camera not working even the icon from the Uconnect disappeared . But the 4WD it’s working apparently . Any thoughts about this new issue in my truck?

Yep. Any time you disconnect power, it takes time for all the computers to communicate. Give it a day.

 

[racterman]

Give the computer time to wake up. Those issues should clear on their own.

 

[racterman]

Yeah you was right, I did a little trip test and everything got back to normal. Just one little detail are spinning in my head. First run the voltage was at 14.1 v but after the little trip the voltage dropped at 13.8. It’s that normal?

 

[ben b]

That's great news! Your voltage fluctuation is similar to what I see from day to day. Not sure why, but I haven't noticed any problems with starting and driving.

 

[racterman]

That's great news! Your voltage fluctuation is similar to what I see from day to day. Not sure why, but I haven't noticed any problems with starting and driving.

Despite of voltage fluctuation everything is working properly. I believe that I reached the final resolution for this issue. I’m very thankful for your comments that help me a lot.

 

[racterman]

Well guys seems like this is the final resolution for this weird issue that drove crazy. I’m very thankful for all your comments and helping determination from you. I’m glad to be part of this forum from now and on. All you contributed to get my truck fixed and that is something very valuable since there is not much information about Ram 5th Gen out there you has been a great support. Here I uploaded my little road warrior my best living tool that you helped to keep running. Thanks to all you guys God Bless you all.

 

[Scap]

Yeah you was right, I did a little trip test and everything got back to normal. Just one little detail are spinning in my head. First run the voltage was at 14.1 v but after the little trip the voltage dropped at 13.8. It’s that normal?

The charging system is smart. It adjusts the voltage as the battery gets topped off.

 

[kapinallinen2]

Well guys seems like this is the final resolution for this weird issue that drove crazy. I’m very thankful for all your comments and helping determination from you. I’m glad to be part of this forum from now and on. All you contributed to get my truck fixed and that is something very valuable since there is not much information about Ram 5th Gen out there you has been a great support. Here I uploaded my little road warrior my best living tool that you helped to keep running. Thanks to all you guys God Bless you all.

Great that you got it sorted out.
There is a ton of good info here on the forums.