my f150 (99,4.6l auto 4x4) sometimes won't start back up after it's been shut off. after a while it starts back up. my son in law crawled under it and said the starter terminals are corroded and he thinks that's it. seems to me if they were that bad, it wouldn't start back up.i'm trying to trouble shoot this myself and don't want to wind up swapping out parts until i get a better idea of what could cause this. it 1st happened on 12/22. next day i cleaned the terminals and it did fine until yesterday. same thing happened. got it towed home, when i went out this a.m., it started right up. anybody got any ideas where to start?

 

Does it "Crank no start"? What's it do when it doesn't start?

 

I'd guess starter solenoid....

 

Had same problem 2-3 times a year. Found it always to be the small battery lead to selonoid. Take female end from harness off of the male blade ,clean both w contact cleaner and a wire brush,add di-electric grease, good for 6 months. I finally cut off the end,attached a loop,and fastened with a brass nut to post on selonoid the male blade is attched to and no more problem. Friend at GM dealer found this a a recommended repair on ALLDATA tech site

 

That or a troubled relay.

 

all lights on dash light up like always, but no sounds from the starter. (no clicks like a dead batt. or anything) i was thinking like the other posters thought, bad cable or wire,if not maybe solenoid. don't think it's a neutral safety switch, or tpss, or whatever it's called now. just wanted a opinion from wiser men than me.

 

Did that , but you must have overlooked. Most likley it is your cables to the starter - specially that little one on the post. . If those have been cleaned, then its the RELAY or the 175 MEGA fuses (if your model has them). A "NO" click situation is one of the either one of the two IMO.

 

all max fuses are ok. relays still click, tho thats no garauntee they are ok. gonna try the wires 1st, then go to these if not fixed. gotta let the truck sit, got a lot of work to do on a new job, will post when i can. thanks to all

 

Same thing happened to me this morning...Get in the truck, key in, all dash lights illuminate, radio comes on, turn key, and absolutely nothing, i do hear the fuel pump pressurize, headlights are very bright, cd works, so pretty sure it isnt a dead battery....I am going to check the starter relay, then the solenoid and starter itself, and I will report back....If anybody else has any other ideas, let me know...

 

That one is usually due to that little wire on the starter corroding up - The previous poster still had the problem after cleaning that wire. The connection is the first place to go. Take a look at the starter itself (the smaller wire).

Be careful if you decide to remove and clean . The post on the starter tends to break off easily. Disconnect the battery and spray it down first w/penetrate.

 

Well I pulled the little wire off the relay, cleaned it and re-installed it, and still no luck....I then did the old screwdriver trick across the terminals and viola, truck cranks just fine....So I am gonna replace the starter relay and see what happens

 

That's probably it then.

 

Well $21 and 10 minutes to swap it out, and im back on the road again...Really weird how one day its fine, and the next day it wasnt..Im just glad it was nothin major...And it looks like by tonight I will roll 200k, just looked at the odometer when I parked...199965.8...