2005 mercury mountaineer AWD issue

[PAford1321]

I have a 2005 mercury mountaineer. I recently started having issues with the AWD becoming disabled when driving and then my ABS light comes on and then ADVTrak light. Also I noticed my brakes become real weird and pulsing when I try and stop. The truck is shifting weird and every mechanic I go to wants to charge me 100 bucks to even look at it. I don't have that money right now just to give someone to tell me the wrong thing. Can anyone help or suggest what may be the cause of this? The truck has 150k on it now so it has high miles but my dad has owned the truck it's whole life and babied it. Any help would be great thanks.

 

[SupaSwope]

Welcome to the fourms. Wrong year section but no big deal. I do not own a AWD but am gonna try and help you with my 2 cents. Sure someone will come along eventually to help more.

Anyway. The AWD going out along with an ABS light coming, That would maybe make me think it was ABS sensor. OR some sensor in the wheel hub causing the AWD to disengage and ABS light to come saying it was not working properly. Now pulsating brakes can be multiple things from air in the system to rotors and pads being worn down.

My first question here is when was the last time the brakes and rotors were serviced? New Pads, New Rotors, or even resurfaced rotors with a lathe. My advice to you would be to educate yourself some (if you dont already know) on how the brake system works. And then get a jack and pop the tire off and see what you can see. I mean this could be as simple as an ABS sensor being unluged. Up until you mentioned the brakes pulsating.

 

[imp]

Welcome to the fourms. Wrong year section but no big deal. I do not own a AWD but am gonna try and help you with my 2 cents. Sure someone will come along eventually to help more.

Anyway. The AWD going out along with an ABS light coming, That would maybe make me think it was ABS sensor. OR some sensor in the wheel hub causing the AWD to disengage and ABS light to come saying it was not working properly. Now pulsating brakes can be multiple things from air in the system to rotors and pads being worn down.

My first question here is when was the last time the brakes and rotors were serviced? New Pads, New Rotors, or even resurfaced rotors with a lathe. My advice to you would be to educate yourself some (if you dont already know) on how the brake system works. And then get a jack and pop the tire off and see what you can see. I mean this could be as simple as an ABS sensor being unluged. Up until you mentioned the brakes pulsating.

@PAford1321 @SupaSwope
Here's my 2-cents. AWD cannot "disengage", ever. Unless a serious breakage occurs somewhere. ABS light ON is used to provide a warning. Doesn't necessarily mean ABS is not working. Advance-Trac really "muddies-up" the waters in that it makes understanding of the braking system go way beyond traditional hydraulic brakes.

My guess is the pulsating brake pedal is being caused by the ABS, and that it is malfunctioning. Late 3rd. Gen. ABS without Advance-Trac works like this: Sudden loss of wheel speed anywhere on the vehicle while braking is interpreted as a skidding wheel. ABS then squirts 150psi of fluid pressure into the Master Cylinder Primary, which effectively "locks" the brake pedal; you cannot push it. Then, ABS adjusts line pressures to the wheels to bring all 4 back into the same speed range. This process can repeat quickly and repeatedly, depending on the skid condition.

Advance-Trac? Does same as ABS, but ADDS Accelerometer signals and Brake Pedal Apply Rate, monitoring body sway, adjusting pressures to wheels alternatively as needed to help prevent roll-over of the vehicle. Complicated? Hell, yes. Not sure even Dealerships understand HOW it works, they service it using Diagnostics. You need to get ABS codes read, as well as Chassis codes. Without them, this is like bobbing for apples blindfolded. imp

 

[SupaSwope]

Holy crap. That sounds entirely more complicated then a 2nd gen.

 

[imp]

Holy crap. That sounds entirely more complicated then a 2nd gen.

@SupaSwope
Beyond complicated, to me, it's insane. I'm an old man, having driven and worked on almost every kind of vehicle over the years. Picked up a lot of knowledge and understanding, some of it the hard way by making mistakes; some were serious mistakes. I love the idea of using tricky little widgets and gizmos, but those the "brains" have now included in today's transportation means are bordering on the ridiculous. imp

 

[PAford1321]

Wow thanks guys for all ur feedback. lol yes some of that does sound complex, I guess what I'll have to do when I have the extra dough is take it to maybe a reputable shop and I hope they don't BS me. I do have one more question though @SupaSwope if I were to keep driving for now since I don't have another way to get to work would it hurt or damage anything even more. Also I put these bigger BFG mud terrains on there a few months back so I'm thinking that may have affected it?

 

[imp]

Wow thanks guys for all ur feedback. lol yes some of that does sound complex, I guess what I'll have to do when I have the extra dough is take it to maybe a reputable shop and I hope they don't BS me. I do have one more question though @SupaSwope if I were to keep driving for now since I don't have another way to get to work would it hurt or damage anything even more. Also I put these bigger BFG mud terrains on there a few months back so I'm thinking that may have affected it?

@PAford1321
Not to worry, actually. If anything is literally in danger, the vehicle will enter one of several modes aimed at immobilizing it. Depending on severity, first is usually "Limp Mode", which code reads out as "Forced Limited Power". Beyond that, "Forced Engine Idle", and finally "Forced Engine Shutdown". imp

 

[CDW6212R]

It sounds like the vehicle has 4WD(Automatic 4WD(A4WD)), not AWD. imp is right about AWD not having any affect on the brakes or stopping 4WD functions, AWD is constant all the time and has no different modes.

If those new tires are all identical in diameter(not same size by different makers etc), then I'd be checking all fluids, change the transfer case fluid now, check ABS sensors for any wiring damage, and otherwise dig into maintenance records and do everything not done recently.