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So after searching past posts for over 2 hours I see that the seemingly random 5.4 failure to even crank is not that rare yet it seems my "Twist" is that instead of blowing fuse 102 (20amp Blue STARTER SOLENOID OR RELAY) all i need to do is simply pull fuse 102 and then push that same exact fuse (not a replacement) right back in a walla it starts 100% of the time. Its frustrating i havent narrowed down the cause of this yet BUT my forum search DID provide a ton of ways to diagnose. My Question is specifically the 2 sec pop out and back in with fuse#102 seems to be unique as every other poster kept blowing and replacing these. I did originally replace it and in fact found out after that cycling it out and in gets the engine to crank and start right after. Is this potentially a clue as to where i should look next or what the culprit may be? Still a novice with auto electronics. Thanks so much in advnce!
-Nick
2004 5.4 F150 fx4 sscrew Flareside
Blazing Yellow
137k miles
34" Goodyear Duratracs on stock 18s
2.5" suspension.level. (Bilstein 5100 ride adjustble)
X2 on this one. ^^^^ I'd try pulling the fuse and replacing it with a new one - to rule out the fuse itself being wonky (highly unlikely) first. You could also try testing the fuse (with a DVM or Test Light) to see if it appears blown when the truck won't start. If either test method shows zero power at both sides of the fuse though, you have a problem with the fuse box.
You could also have full power at both terminals of the fuse (in START) and still have a wonky fuse box. It all depends on where the fault happens to be.
X2 on this one. ^^^^ I'd try pulling the fuse and replacing it with a new one - to rule out the fuse itself being wonky (highly unlikely) first. You could also try testing the fuse (with a DVM or Test Light) to see if it appears blown when the truck won't start. If either test method shows zero power at both sides of the fuse though, you have a problem with the fuse box.
Replacing it was first thing a tried and the brand new one did the same thing. Next time i have an hour so free im going to start tracing electrical connections
Try testing with a volt meter looking for an open when the fault occurs.
The fuse feeds the ignition switch.
The switch feeds a number of other circuits.
Since power feed goes open when in fault, cycling the fuse likely would not affect a remote location.
Likely a loose or intermittent fuse socket or leads that you mechanically move by puling the fuse out and replacing it back.
Not the first time this has happened top anyone.
Good luck.
