In March, turning the key did nothing, and it turned out to be that the starter relay #65 coil was open. Yesterday, the same thing happened, so I swapped in another relay of the same part number. Good again. Is it just my truck, or are there others who have gone through this, and is there a cause?

Thanks

 

I've not experienced any relay issues. I have a 3.5L so no Auto-Stop-Start. As with the starters themselves, I suspect all the stopping and starting greatly decreases the expected life of starter system compenents.

 

3.5 n/a here too, no start-stop. Since it is not the high-current contacts that fail, but the 12 v. coil part of the relay, to me it points to the coil getting too-high a voltage, but I can't understand how this could occur.

 

You could have experienced two poor quality relays back to back. They are pretty well all made in China, regrdless of the brand name. These small automotive relays either seem to last the life of the vehicle, or they fail early in life.

 

Lack of a reverse bias diode across the coil (aka flyback diode) would be my first guess. I would assume Ford is smart enough to build that into the relay assembly, but you never know. Aftermarket, well there's a reason they are cheaper.

 

Both Ford originals - numbered 8T2T-14B192-AB

 

Well, here we go again - no crank this morning. Going out just now to jump the terminals in the relay #65 spot and move the truck out of the way.
FYI, battery new 6 months ago and fully charged. Will edit this post if something changes. Thanks.

Edit - starts fine when I jump the starter terminals. The coil contact pins on the relay read as "open" - no continuity - with my VOM.

 

They are designed for the task. Its not a normal starter.

 

He knows that, as do most of us. However, it wouldn't surprise me to learn from actual data that starters and related components in A.S.S. trucks have a shorter average service life (in terms of miles our years) than the "normal" parts in non-A.S.S. vehicles. Driven around town and commuting, the starter on an A.S.S. vehicle may be used 10x or 20x as often as a normal starter; I very highly doubt it's built for 20x as many lifetime starts. One of many reasons my A.S.S. is permantently turned off.

 

My guess, your starter could be on the blink, maybe a winding shorting?

I Googled, and found this: might be helpful , there actually were many hits.

Why does my starter relay keep failing?
Damage to the starter relay is usually caused by a short circuit due to a poor power connection on the starter.