2005 6.0 intermittent no start

[TylerH]

The last week or so my truck has been acting up, I havnt really been able to determine a pattern. Some days I will go out to start my truck and all it will do is turn over, typically if I screwed with the two relays to the right side of the drivers side battery it would fire up again(what are these relays for?). Today i went to start it and it just cranked, played with relays and still nothing. Does anyone hAve Any ideas as to what the issue could be?

Thanks, Tyler

[NYC F-350]

Any codes present?
Have you checked your batteries?
You battery cable connections?
Your FICM?
Is it only cold starts that are the issue or do you have difficulty with hot starts as well?

[TylerH]

Originally Posted by NYC F-350

Any codes present?
Have you checked your batteries?
You battery cable connections?
Your FICM?
Is it only cold starts that are the issue or do you have difficulty with hot starts as well?

No codes, new batteries, connections looked clean and are tight, have not checked ficm. So far I have only experienced this issue when cold starting.

[NYC F-350]

Typically, I say to remove the batteries from the truck and have them load tested to verify that they are in good condition. If you are confident that they are in good condition you can skip this step if you choose.
Second step is to fully charge the batteries. Put them on a charger and be absolutely sure that they are 100% charged. This is to ensure that the following test is an accurate test of the condition of the FICM.
The third step is to get yourself a multi-meter and a helper and check the FICM using the directions you will find on this LINK.

It is critically important to test and verify that the batteries are indeed in good condition for this test so that you get the best possible results.