OK...I ask that you bear with me while I explain my question/issue.

I bought a used 2006 F350 Super Duty diesel last October (Oct 2015) and it has about 124,500 miles on it now. Last week, the power cut out as I was driving home from running an errand. Jumped it and got it back to the house. Suspected the alternator as both batteries tested low (according to AutoZone). Purchased the 110amp alternator and after a few days...I was able to get the alternator installed. AutoZone charged the batteries back up.

Today, I was able to start the truck and drive it around the block in order to make sure everyone was okay - before I took it out on the streets. Got back to the driveway....ABS light comes on, radio shuts off, odometer light goes off, etc. I shut the engine off and let it sit for a minute. Try to start it back up...and nothing happens. Ended up disconnecting both batteries while I ponder the root cause of the issue.

Is it possible the 110amp alternator is not strong enough to handle the power requirements (and that's why the dashboard lights went out)? To the best of my knowledge, there's only 1 alternator. The only "extra" that's installed is the tow/haul package (which I haven't used yet). According to the Ford Parts web site - after I enter the VIN for my truck - the results show a 110amp alternator (heavy duty alternator).

Would exchanging the 110amp for the 140amp be the most logical place to start? Or is there something I missed as a replaced the alternator?

Thanks -
Scott

 

!st off you wouldn't be the 1st person to get a bad rebuilt alt. 2nd, the dual alt. trucks have a 140 amp alt. that will fit your truck and lastly did you monitor the voltages after you reinstalled everything. After AZ charged your batterys did they load test them again? What was the voltage output when the truck was running?
These are some of the things we need from you to help you diagnose your problem. Do not hesitate to get these answers as low voltage can take out your FICM and a bad FICM can damage injectors.

 

69cj,
Thanks for the reply. I bought a new alternator from AZ. I don't have a tool to test voltage output, so I can't tell you what the levels were. The person at AZ said the batteries "tested fine" when I picked them up. The batteries appeared to be fine a few hours ago when I was able to start the truck and drive it around the block. I don't believe there are 2 alternators installed, as I didn't see a second one on the bottom of the engine block when I was under there checking the position of the belts as I was replacing the alternator.

Is it possible that the new alternator from AZ is bad?

 

69cj,
Are there any voltmeters that you recommend? Or are they all about the same?

 

Okay, first off you MUST get a live data scanner, such as, a Scan Gauge II, or Torque Pro App w/ bluetooth adapter, or something. Without this tool, you cannot properly start to diagnosis what the problem is or future problems.

Also, when you get the load test done on the batteries and the bench test done on the alternator, they need to be cold, as in sit over night.

Welcome to the 6oh Brotherhood

 

Looks like there are a couple of places I can pick up the ScanGauge II. If I can set time aside tomorrow from work, I'll see if I can pick it up and install it.

Is it difficult to install? The web page says it's easy - but it is really?

 

There are a few 100,000 6.0L running around the country with 110a alternators just fine, so no, this is not a situation of too small an alternator.

You may have a malfunctioning alternator, one that is not fully connected to the truck, or really bad batteries. The battery tests done by the retail shops are by no means foolproof. But before anything can be determined it's important to find out what the battery voltage is and the voltage the alternator is providing while running. A $10 Harbor Freight voltmeter can do that, a higher priced unit would be more precise.

While a Scangauge is an essential tool for monitoring the 6.0L (as are others), right now voltage is your primary concern.

 

Very easy. Its just a plug and play for what your immediate needs are right now.

When you get it installed and the voltage issues addressed then you can put all the X-Gauges in to monitor the other sensors.


But the Voltage PID is already programmed in the unit, why not just get it now.

 

It depends on how deep in the weeds this task is going to take him. Yes, it will be easy to see what the KOEO and running voltage will be. We can get creative to check the voltage of each battery individually (pull off one ground terminal, check volts, reconnect then pull the opposite battery negative terminal), but what if like in the other thread there is a voltage drop in the circuit, that we can't check. Or a problem with one ground cable, or the battery to battery cable, or if the regulator is not getting a voltage signal. The Scangauge is not going to be able to be used to get that data. A cheap, simple voltmeter will.

 

Everybody needs a good DVM or DMM. They cost maybe $75 and will measure AC/DC volts to 1000, ohms, capacitance etc. Fluke makes a line of affordable units, there are others. They have lots of uses around the home as well.

One key troubleshooting skill everyone should learn is Voltage Drop Testing. No disassembly or disconnecting is required and it's quick and easy. This is an important test here because ohms resistance cannot be used on high amperage circuits, they must be tested in use while under load. A scangauge is great, but of no particular utility for charging system troubleshooting as such.

And with a DMM you won't have to depend on AutoZone anymore. No offense I'm sure they are great guys, but. Here's why the resistance of the connecting and ground cables and hardware may be the issue in a ten year old truck:

"It doesn't take much of an increase in resistance to cause trouble. Let's say a 120 amp alternator operates in a circuit that has a normal resistance of 0.11 ohms. If that resistance were increased to 0.17 ohms because of a bad wiring connection, the alternator's maximum output would be limited to 80 amps. In other words, an increase of only 0.06 ohms (almost nothing!) would reduce the alternator's maximum output by almost a third! Under light load, the drop in charging output might not even be noticeable. But in a high load situation, the alternator wouldn't be able to keep up."

http://www.aa1car.com/library/voltage_drop_testing.htm

http://www.aa1car.com/library/charging_checks.htm

 

This is true

 

Okay...so the plan for today is to install the Scan Gauge, hook up the batteries, and see if the truck will start. If not, I'll drop the batteries off (again) for charging. Then repeat the battery install and start up the truck.

 

If you can, after charging, let them set over night and then do a load test.

 

I always have an alt tested before I will take it home for ANY
vehicle. I have had a few dead right out of the box. The last one
was DOA and that was this last fall. With the 6.0 if your running a
dual alt system you should have a 140 as the top or at least that
is how they roll off the line.

As for what DMM VOM or volt meter you want to get really any will
do quite well. You don't need to have capacitance or transistor testing.
A Fluke would be nice but your talking more $ money then.
One way to get a nice tool is to check the pawn shops. $35.00 will get
you something that is fair. Fluke,Snap On, Matco, Mac tools even something
from Kline would be good on the higher end of things. The cheap ones from
the home stores are OK too along with auto parts stores.

Just keep in mind the more bells and whistles and name brands the more the price.



Sean <BR>

6.0L Tech Folder

 

Following up on my post from yesterday...

After doing a bit more research, I originally purchased an alternator that wasn't built for a dual battery setup. I took that alternator back to AutoZone for a refund explaining that I purchased the wrong type for the setup that I have. The store didn't have a dual alternator in stock so I went to another auto parts store.

I was able to have both batteries tested - one of which was at 95% of capacity (compared to the CCA), the other was about 30%. Battery charged while the store ordered a 135amp dual alternator (compared to the 110 single I originally purchased).

Last night, I was able to get the belt on the alternator (with help from a friend). I checked the voltage on both batteries this morning (12.5 volts on one, 12.95 on the other). Drove the truck around the block and let the truck idle while I set up the Scan Gauge II. Scan Gauge reported a voltage level of around 11.4 or so while the truck idled.

I'm going to let the truck sit until lunch time and we'll see how it goes.