I've got an '08 Ram Hemi and I was running down the highway this morning when my dash dinged at me...the ''check gauges'' light came on. The amp guage needle had dropped between 12 o'clock and the first thick line on the low side. It stayed like that until I let off of the gas when I got to the next town, when it came back up to a hair over the middle line.

When I checked the system with my volt meter...it was reading between 14.2 - 14.6 with the pickup idleing.

Does anyone have any idea what's going on here? Is my alternator going out or is it as simple as the battery connections need a good cleaning?

Any help would be appreciated. I'm out of town working and I'd have to drive 50 miles to pick up an alternator.

Thanks.

 

I have an '08 and my battery was crap after just 6kmi(3yrs)

Sounds like your battery sensor is picking up a hot battery which limits charge.
I would have your battery load tested. I bet it's no good.

 

I just replaced the battery about a year ago.

It ended up dying on me along side the highway and I had it towed to a dealership. I'm pretty sure it's the alternator, and they said replacing the that falls under the extended warranty, but I could be wrong.

Every parts store and dealership I talked to today said that these alternators rarely go out. Guess I was one of the lucky ones.

 

They don't fail often. Often if the brushes are worn, the alternator quits charging at higher rpms. Sounds like yours has died.

 

That's excactly what it did this morning...then it died this afternoon.

 

I've only known worn brushes to charge low at all rpms, not just high. Your low rpm charge is right about where it should be.
Slipping serp belt can cause erratic charging at higher rpms and the perfect amount at lower rpms like you have! You can take a scotch brite pad to the alt pulley and dull the surface up so the belt has a better biting surface or just buy a new belt if it's needed(usually every 50-60kmi)
Voltage regulator could be getting hot from a bad diode and causing low charge at higher rpms.

I'd do a voltage drop test from the battery terminal to the alternator plug. You should be right around 0.2volts. Anything higher and it means you have high resistance which makes the alternator work extra hard(could be cause of a bad volt. reg being erratic)

These are a few things I would go over before spending a chunk of change and time on a reman alternator which is nowhere near as good as your OEM one, unless replaced by the dealer with another OEM unit.

 

By the time I noticed a problem, I was 70 miles from home so I didn't have a lot of options. I ended up having it towed to a dealership. My extended warranty will cover the alternator, if that's what the problem is. They quoted me a price of $235 just for the alternator, my warranty deductible is $100, so it's probably a better deal anyway...plus they gave me a loaner vehicle. I asked for a Challenger, but they said that probably wasn't going to happen.

 

Dog, it is a common problem on the Ford truck alternators. The brushes won't stay seated on the armature at higher rpm's.

 

Got my pickup back today. It was the alternator. Got that replaced and they found a loose tie-rod, so they replaced that too...all covered under warranty. I just had to pay the deductible which was probably way less than what all of that work would've cost.

 

I had a loose tie-rod replaced under warranty awhile back too when they had to replace a front hub bearing. They found the loose tie-rod when doing the other work. Dealer bill was over $600 I think, but I just had to pay my $250 deductible. Hub assembly and tie-rod installed and a front end alignment for $250 works for me. I'm getting lazy these days