This regards a neighbor's 2002 Ford F150, FX4 package, 4.6L V8 with AT. The problem concerns the ABS control module (4 wheel ABS system). This started with a parasitic battery discharge that was getting progressively worse. At first the battery would discharge over a 3-4 day period and in short order progressed to an overnight discharge with a drain of 5-6 amps with the key off, engine compartment bulb removed and no other bulbs or accessories on. The battery checks out good as does the alternator. I started pulling relays individually to checking for a potential source and none changed the current draw. Then I started pulling the small fuses in the power distribution box and no problem was found. I then started with the "mega fuses" beginning with the 50A ABS fuse and the battery drain stopped. To recheck the problem I replaced the 50A fuse only to have the ABS control unit start smoking and the multimeter got extremely hot really quick so I instantly removed it. I visually checked the ABS module while still on the truck and can see nothing obvious. The smoke appeared from under the rear portion of the unit opposite the electrical connector and near when the brake line attachment points.

I should point out a couple of things. First the truck only has 75K miles, the body and interior are flawless. The frame and other underside components are extremely rusty as the truck was operated in Canada for its first few years by the original owner (my neighbor purchased it used). To illustrate the rusty condition, the tube that runs from the exhaust manifold to the EGR valve was recently replaced since it totally broke as a result of the rust.

In addition, while changing the front brake pads and rotors 3 weeks ago the front brake lines had to be replaced since they where rusted to the point where the lines broke at the metal/rubber junction on each wheel. Due to rust the lines were extremely hard to loosen where they attach at the ABS control module.

I am theorizing that something happened internally to the ABS control module that resulted in a short circuit. The battery drain did not occur prior to the brake line replacement so I think the problem began at that point with the slow battery drain that finally led to a "dead" short that caused the unit to smoke.

Can someone let me know if my logic works before I remove the ABS control unit. Are there additional tests or other components I need to consider?

Thank you for the help.
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I noticed that the ABS on my 2000 f-150, had A small electric motor on it. After I turned the engine off. it continued to run.Disconnected the wire to it. Don't know if this is harmful, but I still have brakes.

 

I am experiencing the same issues with my 2001 F-150 Lariat. Ever since I replaced my front rotors and pads, my battery has been draining power. Its a new battery, bought in January of this year.

Jonesky, Wondering if you ever found the problem and were able to correct it.

 

Hope this will help. ABS Module Repair | ABS Repair | ABS Module Replacement

 

If you can solder and work with electronics, you can usually repair the module with a < $4 part.

Or you can send it off for repair ($100-200) or replace it ($300 for a reman or $850 for a new one from Ford).

In the meantime, unplug the ABS module (or remove its fuse) to keep it from running down the battery. You will have standard, non-ABS hydraulic brakes and an ABS warning light.

 

My local junkyard sells these parts, used, for about $60 if you pull them off the truck yourself. For an extra charge, you can even return one that proves to be faulty. They regularly get F150's of that era, and those get picked over pretty thoroughly.

 

So what is the $4 dollar part?

 

This is supposedly the part - a MOSFET chip
SUM90N06-4M4P-E3 Vishay Siliconix | SUM90N06-4M4P-E3CT-ND | DigiKey

 

Just want to say thanks to all of the above who responded. I removed the fuse and next I'll start digging at my local junkyard. Fun times.