Looking for suggestions, please. When the problem first started (last week) the truck wouldn't start and there was a single loud 'click'. Not even trying to turn over, just the 'click'. Considered the battery first, tried to jump start, but no change. Still just the 'click' and auxiliary items all functioning. Confirmed the battery was not dead using both a battery tester and voltage meter. Going through the manual it sounded like it might be the starter. Changed that out, still no start. Have tested the cables, the relay, all good. Gave the battery cables a good cleaning. Then the symptoms changed a bit. Still no start, but now there's a bunch of clicking noises coming from the fuse panel under the driver's side dash. When I searched that on the forum the fix was the battery (a couple mentioned fuses but overall it seemed like battery was the way to go). I pulled all the small fuses out to make sure they are not blown. Took the battery to the parts store and they confirmed it is still good but a little undercharged (no surprise there since it hasn't run in 2 weeks). They are charging it now.

What else can I test? Or is this beyond DIY?

Been working on this for a few days now and enlisted the help of a very knowledgeable neighbor but am about to give up and get it towed to the shop. Thought I would see if anyone here might be able to help first.

 

Check the megafuses.

https://www.f150online.com/forums/v8...mega-fuse.html

 

Remove the serpentine belt and see if it then cranks.

 

Is there another name for Mega Fuse? Advance Auto parts can't figure out what I'm referring to even after explaining what and where it is, 175A, etc. Also, what's the purpose to cranking without the serpentine belt? What is that testing for?

 

It's testing for a seized belt-driven component - alternator, PS pump, A/C compressor, water pump, idler and tensioner pulleys.

Test your mega fuses with a meter. You should be able to read the part number on them, take a pic and bring that to the store, or bring the fuse itself in. You may have to go to the dealer.

 

No, use a different store (Oreillys, NAPA, Pep Boys, etc). AAP and Autozone do not carry this fuse. Probably doesn't matter anyway since the starter power doesn't go through a megafuse.

Seized accessory (A/C clutch/compressor, alternator, PS pump, etc).

Missed this earlier. This suggests that you have a power/ground problem due to excessive resistance. You will need a multimeter to further troubleshoot this. Do you have one?

 

Does it crank if you manually jump the solenoid on the firewall?

 

Missed a few replies on here so I'll try to catch up and update the situation. We previously used a breaker bar to turn the crankshaft and it turned fairly easily (forgot to include that in the first post). The serpentine belt was in place so that proves it's not a seized component, correct?

No, the engine did not crank when shorting the starter relay.

My neighbor felt really strongly that it had to do with the battery cables. We had already scrubbed them and tightened the clamps but he returned and actually cut and stripped a new section, used a dremel tool on the clamps, and put everything back together. Now it cranks but will not turn over.

I searched this on the forum and some had luck with replacing the power relay but another had a bad fuel pump. By the sound of the cranking, it does feel like it's a fuel issue. I'm going to try a couple of new fuses since they are easy and cheap.

Any other thoughts?

 

When you turn the key on, do you hear the fuel pump buzz for a few seconds? You may need someone to cycle the key while you listen by the tank.

It seems strange that after fixing the no crank situation, you now have a crank, no start situation. I'd concentrate on the areas that were worked on to make sure everything is still hooked up properly.

 

I cannot hear the fuel pump. Fuses were no help.

 

1 Check inertia switch. If okay, go to 2.

2. Check for power at the inertia switch during pump prime cycle. If okay, go to 3 otherwise check FP relay and circuit.

3. Check fuel pump operation.

 

Got fed up and towed it to the shop. They tell me there was a diode missing from the power distribution box. I never touched that so I'm still perplexed but at least it's running again.

 

I'd blame it on your neighbors help. That diode, which is in the circuit that energizes the PCM Power relay (which turns on the computer, the ignition, and the fuel supply systems) did not just grow legs and walk away by itself. It's a mandatory requirement for the engine to run.

 

My neighbor is a pretty meticulous guy whom I trust. Could be that it wasn't missing but maybe gone bad? The shop did not like that I did some of my own troubleshooting. Before they figured out what was wrong, they had the nerve to ask if I'd tried to jump start it 'backwards.' As a woman and a former Army mechanic, you might guess I was a little offended. I don't think I'll be going back there.

 

Thanks for all the pics and help you sent me, glad to see you have yours repaired. Do you have a pic of the diode and where its located?

FWIW, I found a fuse box and harness from a 98 with a 5.4 that I am going to use on my project.