Truck Girl

Well guys,

Something more than the batteries or alternator has to be wrong. Yesterday morning when I got into town to do some shopping I could smell something electrical. A quick look under the hood and I saw the starter smoking. I called Lithia Dodge and they wanted $600+ for a new starter and they didn't have it in stock! I figured I would take my chances finding it elsewhere as that was just absurd.

I got my groceries, put them in the truck, and then walked the couple blocks to the local parts store. Would you believe they actually had the starter in stock? It was a rebuilt unit, but it was only $136!

So, new starter in hand I went to the truck with my fingers crossed. I got lucky, it started. I could still smell the electric smell all the way home.

I changed the starter, but when I started the truck again it was not charging at all. When I started it the voltmeter was right around the line at 11V, but once it was running it started dropping. The time display on the radio went blank and the voltmeter was really close to 8V! I shut the truck off, thinking that maybe since the starter went bad it drained the batteries. I hooked up each battery to a charger and let them charge for just about an hour. They both came up good to 13.0V again. I hooked them back up in the truck and started it. Still not charging! What in the heck can this be? I am about to take it to the dealer because I just can't keep throwing parts at this and not solving the problem. I've checked and cleaned the grounds, replaced the alternator, checked and cleaned the terminals, replaced the starter, what could be next?

Does anyone have any other ideas?

Thanks again for all your help!

Truck Girl

nickg

I would PHYSICALLY check every cable from battery to battery, from alt to battery, from battery to starter for loose connections and or chafing as it could have rubbed thru,
I don't recall if you ever did say you had the batterys load tested?

For what its worth the dealer is likely to do everything you have already done and charge you huge $ take the starter for example, you just saved 450$ for walking down the street
I wonder if your old starter was stuck on ? as that would kill the batterys pretty quick, just starting the truck should not be enough to kill the batterys.

Oh yeah just remembered check the wires near the alternator IIRC they chaf thru near the alternator housing and cause a no charge condition.
FWIW I've seen 3 "new" alternators put on a GM within a week and all that was wrong with it was the alternators were faulty. dont fall into the trap of thinking cause its new its good. Find a good electrical shop (they usually rebuild alt/starters) they will usually diagnoise for free or charge a minimun price for diagnoises.
Also the best way to be testing with a multimeter is checking output when the truck is not charging, then you can eleminate the alt if its charging, Dont have alot of faith in the in cab gauge.
Feel free to PM me with your phone number if you have questions

Truck Girl

Nick,

I was thinking exactly what you have stated. When this truck was new it went through three brand new alternators within the first 8500 miles. The original one had a bad bearing so it was eating the drive belt, but the second and third would not charge. I think I will have it tested somewhere and then check back with you.

I'll drop you a line tomorrow with my number. Thanks a bunch!

jrs_dodge_diesel

Also, you should check the main fuse box under the hood. There is a 140 amp fuse for the alternator output. Might want to see if it is loose.

94Stepside

I would check all the grounds my truck did something similar to this and all I had was a bad ground, to bad it killed my starter before i had a chance to fix it.

Truck Girl

Ok guys,

I'm gonna go get the charging system tested this morning. Turns out we have a friend who has a DTAC testing system. Hopefully this will point us in the right direction and I can get this darn monkey off my back.

As for the grounds, I've cleaned and check them all.

I'm really starting to think it is just a bad alternator. From what I have heard it is not uncommon to get a dud right out of the box.

We should know something here in about an hour or two!

Truck Girl

Well I think we got it. The only real conclusion that we were able to come to was that the starter was sticking on and causing the voltage fluctuation. The old alternator was weak so it wasn't able to keep up with the demand. That is why I was getting the P1682.

When I replaced the alternator it was now capable of supplying the additional power that the starter was demanding, but it was putting out too much. The output stud and terminal on the alternator got so hot that the nut completely melted and that was why the system was not charging at all over the weekend. Fortunately the stud didn't get too bad and we were able to re-thread it and put a new terminal on the output cable.

After we put it back together we tested the system, I actually got a printout of the test!

Batteries:

State of health 100%
State of charge 50% at time of test.

Starter:

Cranking Voltage 10.81V Normal

Alternator:

No Load 13.80V
Load On 13.73V

Diode Ripple Normal


The only thing that doesn't make sense is how/why that nut on the output terminal got so hot. Doesn't the power from the alternator have to go through the PDC and that big 140A fuse? If so why did that fuse not pop? Could the heat generated have actually been so much and so brief that the nut absorbed it all and then fell off thus protecting the fuse?

Thanks again for all your help guys!!!


Truck Girl

Grider Pirate

140 amps is enough to do some serious welding. It's unlikely that you could pop that fuse with anything less than a full short to ground. The Stud and terminal melting is probably less of a mystery. If the terminal to wire connection, or the terminal to stud connection wasn't very good (no looseness, no corrosion) then it would be seen by the 'trons as the high resistance point and get very hot. Under normal conditions, your alternator wouldn't be putting out all that much, but with your batteries drawn way down, it was working it's figurative butt off trying to bring them back up to full charge, and putting out as much current as it could. All that current going through the stud/terminal/wire probably generated the heat that messed up the stud.
My $.02