I turned the key and it started to crank and slowly started to whine down. Tried it a 2 more times and it did the same thing only with less strength and on the third try all I hear is the starter clicking. Both batteries read 12.57 on my multimeter while not cranking. Does this sound like an alternator? All my electronics seem to have plenty of power.

 

if the only thing is does is click... you have a battery problem. And then I'd be looking at the alternator as well, it doesn't really give starting juice. Just because it shows 12.57 volts doesn't mean it will carry the load. I'd take them out and over to be tested, Advance, Autozone....

Any gauges besides the dash?

Turn the A/C to off and try again. If it's still just dying..... clicking, go get them tested.

One click or a bunch? One click is the starter, lots of clicks... battery.

 

I have a volt gauge that reads just over 10 volts right before cranking it. I'm going to pull both batteries out and run over to autozone for testing.

 

So far I have 1 good battery and 1 low. Charging the low one to see if it holds. If not then I'll be looking to grab 2 batteries. It was the passenger side that was bad. Would a bad alternator drain just one battery, both equally, or just the passenger side one due to it being connected there?

 

the glow plugs draw a lot of voltage from the passenger battery. When the key goes on, it could run the plugs for 90 seconds or so depending on engine temp. Cold engine longer than warm engine. 10 volts isn't good, FICM draws some voltage as well and with lower voltage, it could be damaged... but for sure. Fix the batteries and then test the output of the alternator, should be above 13.2 after glow plugs cycle off, anything less than that is good indication you have a bad alternator.

Clean the go\rounds on the negative battery cable where they conne3ct to the frame and body, both sides as voltage flows from negative to positive and a good start is a good ground connection. Clean them with a wire brush or something like that. It will also increase your voltage overall by doing that.

Advance Auto offer a great on-line coupon TRT30. Gets you 30% off most thing up to a $50 discount. Anything above $150 still only gets you $50... so check out when the cart gets to $150, no limit on amount of time you can use that code. 3 items, check out 3 times to save the most, especially for a batteries and alternator, should save you $150! Then pick up your parts at the store.

Batteries should be 12.6-12.8v and even if it was at 12.6, I'd still load test them. If they are bad or the alternator is not capable of outputting the required voltage (remember, batteries only start the truck, the alt carries the load) DO NOT hesitate to replace them as low input voltage to the FICM will kill it. Another $500... no thank you!

Batteries might last 5 years, mostly 4 or so and it's recommended to replace both at the same time... but if they are bad, wouldn't be surprised the alt goes down within a month and the real reason the batteries died.

 

Ok I dropped in 2 new batteries and it fired up. However assuming I did it correctly I connected the multimeter to the batteries with the truck running on idle still 12.5 I then turned on the lights radio AC and was at 12.4. Shouldn't the volts have climbed with the truck idling?

The only time I noticed the volts climb was when I drove the truck around the block my volt gauge climbs to 14

 

RPM drive the output voltage. At idle it should be 13.2 or more and at speed around 13.6 or more. Drive it over for a test.

 

Ok I did another multimeter test and have 14.1 at idle. With headlights and AC on it drops to 12.6-12.7 and holds there. Is this ok? Also if I drive around the volts climb to 14 with everything on

 

As WatsonR posted above, the glow plugs pull a lot of juice with key on until the PCM turns them off. You should see the voltage climb back up to 13+ after they turn off. So make sure your readings you are taking are after they turn off.

 

That looks good.
Monitor main voltage
FICM output voltage

 

If/when the time comes to replace the alternator here are some options in place of the stock one. Especially on the Excursions, they are power hungry beasts - at least mine is. With dual A/C blowers and all the extra accessories the stock alternator really gets pulled on hard at idle.

1. O'Riely Auto sells remanufactured ($160) and new($200) 140 amp alternators for less than the stock 110 amp replacement. These are used in the dual alternator setup but are a direct bolt on and will work on the single alternator setup. Here are the links:

Ultima 01-3821 - Alternator | O'Reilly Auto Parts

Ultima 01-3768 - Alternator | O'Reilly Auto Parts

Ultima Select 392570 - New Alternator | O'Reilly Auto Parts



DC Power 185 amp alternator is a great upgrade as well but costs $300+. But IMO this is what should have been there in the first place.

https://www.strictlydiesel.com/p-366...lternator.aspx

 

Even though those nice, pretty colored alternators put out a bunch of amperage, they still only use standard rectifiers and diodes. Warranty service takes forever because they wait for yours to arrive and then determine if it was your fault... most likely not covered and they don't give a lifetime warranty in a lot of cases.

For that matter, get the 250 amp alt off eBay for $170.

Buy a 2005, 140 amp at your local parts supply store, get a lifetime warranty and service down the street in minutes, not weeks and avoid the hassles.

Keep the batteries charged, monitor your alternator output voltage and don't worry. If an issue comes up, use the warranty and 30 minutes later your back in business.

Let's see some numbers in the morning. Remember that hot oil is thinner and cold oil is thick, it helps build pressure easier. So we need to see both cold and warmed up till normal temps if possible.

 

Morning update. Started right up after about 1 minute I had 14.2 on the multimeter at idle and 13.2 with a load on it. I think it's safe to say the alternator is good for now. I will consider upgrading to a stronger one in the near future to avoid any issues. I'll tell you I've had this truck for almost a year now and I've invested just over 4K into ware and tear with upgraded parts. Not to mention undoing all the hack jobs that were done by the previous owner. By the time I'm done with this it will be better than new.

 

Good to hear!

 

Sweet, I hate when vehicles are down.

On the repairs & investment - I have shared that pain and suffering. Took me 2 years to get my 7.3L excursion to where I wanted it. More than a year on the suspension and repairs to get her solid before even attempting the power upgrades.

But as you know - the Excursions are one of a kind and I would go through it again. They are great vehicles.

Sounds like you are all set. Best of luck with your Ex.