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Mopar1973Man

Alternator & PCM failure

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Believe this repair just saved me the same headache you just had, put in the 5amp inline fuse and 140amp breaker. Haven't started truck in 3 weeks (out of country for work) the alternator I rebuilt this summer was squeaking somewhat. 10 mins later is squeaking its heart out loud n proud. End result is it tripped the breaker, diode is shot and the rear bearing was toast. Rear cover was hot. 

Here I thought the squeaking would stop after it ran some. Boy was I wrong. 

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5 minutes ago, Mopar1973Man said:

Did it blow the field fuse too? I'm curious... 

 

I'm glad the breaker worked out for you and kept the truck from being damaged. At least my misfortune became your savings.

 

Nope fuse was good. I checked that also.

And breaker did its job thankfully. but we've all been there as the one who finds out the bad stuff first. Like when the Dana 80 checked out on me few years back. Passenger side hub gets Less oil.

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On 12/22/2018 at 7:59 PM, Towrigdually said:

 

Nope fuse was good. I checked that also.

And breaker did its job thankfully. but we've all been there as the one who finds out the bad stuff first. Like when the Dana 80 checked out on me few years back. Passenger side hub gets Less oil.

Just keep thinking, guy is got to get lucky once in awhile. Good thing you did the mod when you did. 

I also did mine, it sure is nice having a piece of mind now. 

One thing though, are used a fuse holder that has an LED or some sort of the light that lights up when fuse blows, got it at Walmart. I like the idea I'm just not sure if that light will let current through. Any thoughts anyone?

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11 minutes ago, Dieselfuture said:

I like the idea I'm just not sure if that light will let current through. Any thoughts anyone?

 

Yes it does. It uses the unpowered device as a ground plane to light the LED so there is current flow but very small. 

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4 hours ago, Mopar1973Man said:

 

Yes it does. It uses the unpowered device as a ground plane to light the LED so there is current flow but very small. 

Do you think it would be enough to hurt anything

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33 minutes ago, Dieselfuture said:

Do you think it would be enough to hurt anything

L.E.D.  Stands for Light Emitting Diode.  It only emits light when power is applied across the L.E.D. in the correct direction, and it usually has a 470 ohm resistor in series with the diode (if my memory still works).  That limits the Current through the LED.  So to answer your question no.  No damage downstream.

 

Michael

Edited by int3man
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4 hours ago, Dieselfuture said:

Do you think it would be enough to hurt anything

Milliamps worth. Be aware wiring or device failure can cause the LED to not light even though the fuse blew. I've seen this few times.

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1 hour ago, Marcus2000monster said:

Is they’re a wiring diagram for this circuit breaker?

 

Just like a fuse. Just wire it close to the battery. This gets lugs and wired in like the fuse on the alternator charge line.

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39 minutes ago, Mopar1973Man said:

 

Just like a fuse. Just wire it close to the battery. This gets lugs and wired in like the fuse on the alternator charge line.

So were wiring the breaker and the fuse both into the blue alternator lead?

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16 minutes ago, Marcus2000monster said:

So were wiring the breaker and the fuse both into the blue alternator lead?

 

No. 

 

Blue wire gets a normal ATC 5 amp fuse and holder.

 

Black large gauge wire (charge wire) gets the 150 Amp breaker. 

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This is just another of the great threads we see around Mopar1973Mans website and makes me glad to be a part of helping support this great community of helpful Cummins enthusiasts

 

One question..... Mike your picture of the 5 amp fuse holder shows a heavier gauge wire coming out both sides of the fuse holder, heavier than the blue wire itself, would this wire help to absorb enough heat to cause the fuse to burn a bit late in its ability to protect the PCM? ?

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16 hours ago, JAG1 said:

your picture of the 5 amp fuse holder shows a heavier gauge wire coming out both sides of the fuse holder, heavier than the blue wire itself, would this wire help to absorb enough heat to cause the fuse to burn a bit late in its ability to protect the PCM? ?

 

Negative, the extra copper won't absorb energy. All of that current still has to flow through the fuse element, and the fuse element will still heat up the same regardless of conductor size. So you're safe no matter what you use.

Edited by kzimmer
Removed a rogue 'z'
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No. The gauge of wire doesn't matter. My solar panels are hook up on 2 ought cable and have only an 20 fuse. Fuse is a designed weak link so the fuse fails before devices, wiring, or fire is created. Hence why opt for the 5 amp and not the 7.5 amp.

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