A couple of days ago, I turned the truck off after getting home from work and heard a humming sound coming from the engine compartment of the truck. I went inside and check about 5 minutes later to see if it was still doing it. It was, just not as loud. I tried to start the truck and it would not start. Dead battery. I hooked up cables to jump it and the sound started as soon as I connected the cables.
Could the starter still be engaged? How do I diagnose it?
2000 Ford F-150 with 5.4 liter.

 

1st thing you need to do is pinpoint where the noise is coming from, this will help with that.

http://www.harborfreight.com/mechani...ope-41966.html

Perhaps you could take a video capture under the hood and post it to utube then bring us a link, there are tons of knowledgable people in this forum.

Welcome to the forum.

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Any suggestions as to what the sound could be. Without the engine running, I wouldn't think you should hear anything other than the fan still going. but that was not it.

 

It won't be the starter. That's not how they work. I suspect maybe a fan motor or even your fuel pump on the tank. RnlComp is correct. There's no way of telling what it is w/o an audio of the sound and or it's more specific location. If it is the fuel pump it could be any number of things in the system not allowing the truck to reach operating pressure and shutting off. You might even have a bad alternator or battery.

 

OK, now what?

 

Unfortunately the video won't play. Says it's private. You might try keeping the jumpers hooked up so you have full power allowing you to search out the noise w/o killing the battery, or hook up a battery charger while looking. In the mean time as a temp solution, get a small Harbor Freight solar panel that you can put on the dashboard and trickle charge it through the cig. lighter.

 

Please try the video again. It works for me. I shows me unplugging the power to the fuel pump. When I unplug it, the noise stops. A mechanic at the company shop (I am a truck driver) had me try to replace the relay. Unfortunately; I cannot find my owners manual (too many people driving it while I am out on the road). I plugged in the new relay in all the spots of the same size and none worked. So unless there is another relay box somewhere; I am stuck.
Any more suggestions?


I just changed the video to public. My mistake! This is my first YouTube video.

 

It's hard to identify the part w/o knowing where the camera is located but it appears this is your ABS brake unit. I've never heard one running dry like that, but you might start the truck step on the brakes and see if you can force a Check Engine Light code or an ABS light on the dash. These units are expensive and you may want to spend $65 and have it scanned by a shop, to confirm this is the problem before buying a new one. BTW nice video

 

That is definitely the ABS hydraulic control unit making the noise and it shouldn't be, it should only energize during an anti lock braking event, I think it may come on for a second or two during start up when it self tests.

Going to have to hook up a computer to test the system. If you unplug it you will have normal brakes but won't have the anti lock feature meaning if you slam the brakes the wheels will lock until released, safe to drive in any event.

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So those are brake lines coming out the back of that unit? I just assumed they where fuel lines. It's not just replacing the unit? I definitely can't afford to take it to the dealer to hook the computer up to it. Any suggestions?