I see you had a post about this in February with no replies:
hi, I'm having the intermittent abs engaging as I make right turns and sometimes driving straight. Can I just unplug it so abs wont come on or will this mess something else up? I unplugged it today and drove around the block and I don't have the ABS issue anymore. but the message center says...
www.explorerforum.com
Do you know which sensor it is? A scan tool, or dongle that works with Forscan app, can show you the reported speed on each sensor, or if it activates when you are nearly stopped, going straight, and it pulls to one side, then it would be the front sensor on the side opposite to the direction it is pulling. Wait, you stated you unplugged the sensor so you know which one it is! EDIT:
On second thought that is not necessarily true, if you have a bad sensor and unplug a different one, it may still deactivate ABS, so you may know but we are not presented with that info.
You probably do need a new hub, or replace both while you're at it since they're the same age. You mentioned the 2 pack on 1A Auto for $140. Good price, but since 1A Auto has a little more markup than some of their competitors, they are probably 2nd tier quality, not as good as say a Timken, Moog, SKF, or ***. I haven't researched your specific model year elsewhere, but Rock Auto tends to have the best prices on these brands:
Brake & Wheel Hub Parts and More for Your 2005 MERCURY MOUNTAINEER at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.
www.rockauto.com
Then again, might not be the hub, next most likely might be wiring damage. Once you determine which sensor (which you already have?), could measure for resistance of the sensor, and measure for a low voltage AC signal (when the wheel is spinning) at the ABS controller. You can note the wire colors to determine which two they are at the controller, at the harness connector to the ABS sensor if not on the sensor wire itself. You could also measure for continuity (resistance under 5 ohms) between the sensor harness connector and the respective pin on the ABS controller connector for both wires.
Backing up, you could also jack it up, pull the wheels and check the hubs for smooth rotation, wobble, listen for noise. If there is any, replace the hub.
I had a hub go bad and didn't notice any play in it yet, and the sensor was fine except broke the casing while I was removing, but electrically measured fine at around 420 ohms. I formulated a theory that what was going on was the bearing wear was putting metal particles in the grease on the tone ring in the hub, and flinging it on the ABS sensor. I could have tested that theory by cleaning the grease off the sensor and (using a toothbrush or something) out of between the teeth on the tone ring, but I figured that even if that worked, soon enough dirty grease would be flung around again so might as well just replace the hub.
Replacing 2nd hub at same time, that's up to you, as mentioned previously they are the same age, but it's not really that much more work to only do one at a time as needed instead of both at once, unless you're having a shop do it then they might give you a price break to do both at once. Some people state you need a new axle nut. Technically it is advisable, but I reused mine and had no problem doing so. It was not very rusty, nor were the axle threads which was hard to believe, but they were in good shape. I should clarify all the above info relates to my 2nd gen '98, not an '05, but should be very similar if not identical in the issues faced.
