Hi I'm new to this thread and I'm needing help with my truck. It's a 2006 6.0 Powerstroke with about 200,000 miles on it. My truck won't start seems to have no power won't crank no click no power on the odometer or inside cab period. Took batteries to get checked turned out bad so I replaced both batteries and went to get alternator tested and tested good. Only way it'll start is if I get it it jump started an even then it cranks but won't last more than five minutes running, no mods to truck all stock. Can someone help me with my truck.

 

First, check the condition of your batteries. I know you said you have new batteries, so we'll assume they're not bad. However, even new batteries need to be fully charged to start that 6.0 diesel engine.

Voltage [measurement] 1) With engine not running and all battery cables still connected, measure the voltage on the passenger side battery, right at the positive and negative poles of the battery.
Write this down as voltage 1
Voltage 2) With engine still not running, take loose the positive lead from the passenger side battery. Then check the voltage on the passenger battery, right at the positive and negative poles.
Write this down as voltage 2
Voltage 3) Reconnect the positive lead on the passenger battery, then take loose the positive lead from the driver side battery. Then check the voltage on the driver side battery, right at the positive and negative poles.
Write this down as voltage 3
Important...do not disconnect driver side battery before reconnecting the drive side battery...this will not damage your truck, however, you will need to drive around for awhile to get the tuning re-calibrated. You can avoid this by leaving one battery connected at all times.
Voltage 4) Reconnect the positive lead on the driver side battery. Then connect the volt meter on the passenger battery positive and negative leads. Have someone turn the key, check the voltage as soon as the engine starts cranking.
Write this down as voltage 4
Voltage 5) Continue to crank for 15 seconds and then check the voltage.
Write this down as voltage 5
This series of tests simulates what a battery tester does.
Tell me voltage 1 through 5.

 

I really appreciate the help, ill be sure an let you know what voltage I get off both batteries.

 

Another question would I interrupt the test by jump starting the truck cause that's the only way to get the truck to crank it won't start on its own.

 

Don't worry about whether it turns over, just record the voltage when you turn the key.
Sorry I didn't look at your response last night.

 

Hey bustedknuckles sorry it took me so long to reply. I did just what you asked batteries came out good. So my last option was to check an see if a bigger alternator worked so I went autozone an bought me one with 140 amp an it worked but now my truck is doing the same thing again. Can you tell me how big I need to go on my alternator to keep my truck running. Thanks

 

I don't mean to scare anyone out of this forum, but I frequent the FORD TRUCK ENTHUSIASTS forum and find that it's a fast moving forum. LOTS of info from the guys who are fanatics of the FORD 6.0L. That's just my 2¢. Again, no offense intended.

 

Jaime,
Can you give me the voltages I asked you to record?
This is just the first step in the process.
It's not possible, yet to tell whether batteries are good or bad, based on these questions alone. They are just the first few steps in the process.
There's a process that can be followed to determine the problem, and it's fairly simple, but there is definitely an order to follow.
Without going through it in order, it's easy to get confused and make a wrong conclusion.

Can you give me an update on where you are?

 

You need to check the power cable on the crossover clear down to the starter and make sure it isn't broken anywhere I've had these brake before also check the power cable from alternator to battery's and all fuses and relays

 

If everything in your truck is working properly, all connections good to batteries and good batteries and you still need more alternator output for lights or accessories, look at DC Power engineering. Their stuff is made from beginning to be higher output, not modified stock parts pushed beyond their limits. You can run a single alt., reliably, and get power you need ! No more dual alts, etc.