OK, here's the long version of my deal--still not 100% sure what's going on, but yesterday on the way home from work--minding my own business doing about 50 mph--truck just shuts off. I've had this sort of thing happen before about 40k miles ago, so I'm thinking CPS--when I didn't get tach movement after trying to restart it I just knew it was CPS.

Last night while the truck slept in the spot I rolled into, I got on here to find out that Ford now sells them for a reasonable price--great news!

So this morning I hop on the motocycle and get two CPSs (I know should've did that last time). Replaced it, she fired right up, and after loading my motorcycle in the back I took off to work--problem solved.....or so I thought.
About the time I roll in the parking lot at work--dead again! Same symptoms. No tach needle--and this time I noticed my WTS light did not come on (could have been true yesterday--was too focused on the tach needle to notice).
At quitting time, I crawl under the truck with the new spare CPS and this time it does not fix it! Still no start. I started checking fuses and all were good. Then I get to the relays. There are three in a row with identical part numbers 1)PCM power relay 2)blower motor relay, and 3)Injector Driver Module Power Relay--just guessing, but I get lucky on the first try by switching the PCM and blower motor relays--dang thing fired right up! Checked the blower and it sure enough it doesn't work. So now I'm heading to the local auto chain store to get another relay--all the sudden I notice the blower starts working! Guess what I was experiencing was an intermittent bad relay.
Now for my questions:
Would anything have caused this relay to go bad--in other words is it merely a symptom of another problem? Truck is 2000 F350 with only 94k miles--is a bad relay normal? Should I leave the motorcycle in the back for a little while?

 

its not normal but it does happen. the contacts burn out, it might just been defective one from the get co. but good you found the problem. and ill be checking them guys when CPS wont fix the problem.

 

Bad contacts are the same thing as a short. They can be intermittent and drive you crazy. I'm not sure how you were smart enough to figure this out so quick, but I'm impressed. Also carrying the motorcycle in the back so you don't get stuck walking isn't a bad idea either.

 

Looks like we need to start carrying a spare relay or two now.
Thanks for the update.

 

Dang it!!! Another part to add in to the "spares box" behind the rear seat!!! But I'm about to drive 1700miles one-way to see the family for Turkey Day, so I better do it. I don't think my load rating will suffer too much... haha

 

Great catch. I would have two in your case in the event something is causing that, but I think you will be OK. Thanks for sharing that here. Reps to you on the way.

 

Fuses and relays. Had spares in the truck since I got it. Our trucks have two completely different "form-factor" relays. Carry them both.

Pop

 

Where are they all located??

 

Relays like fuses can get hot from time to time. Fuses blow and relays open when they get hot. That was a great catch though. Sixpack

 

I'd like to say it was my smarts, but it was really just luck--and this forum that helped me catch it. (I do have enough smarts to consult with my faceless panel of experts on this awesome site). When I first had the problem, I got on here first thing when I got home--that's how I found out they finally quit ripping us off on the CPS. I also ran across a post that mentioned blown fuses. The relays I'm talking about are at the upper right (as you are standing in front of the truck) of the fuse panel under the hood. Three of them in a row. Top one is the PCM and middle one is the blower. If you get caught somewhere, try swapping them. At less than $10/relay, not a bad idea to add one to the glove box--put it right next to the CPS kit (CPS,10mm wrench, and a small pry bar).
I might regain enough confidence in the beast this weekend to remove the motorcycle--but I must admit, it looks pretty cool back there!
Thanks for all the help you guys give!